WEBVTT 00:00:00.000 --> 00:00:02.640 align:middle line:84% The following content is provided under a Creative 00:00:02.640 --> 00:00:04.000 align:middle line:90% Commons license. 00:00:04.000 --> 00:00:06.400 align:middle line:84% Your support will help MIT OpenCourseWare 00:00:06.400 --> 00:00:10.080 align:middle line:84% continue to offer high quality educational resources for free. 00:00:10.080 --> 00:00:13.320 align:middle line:84% To make a donation, or view additional materials 00:00:13.320 --> 00:00:17.280 align:middle line:84% from hundreds of MIT courses, visit MIT OpenCourseWare 00:00:17.280 --> 00:00:19.383 align:middle line:90% at ocw.mit.edu. 00:00:19.383 --> 00:00:20.800 align:middle line:84% MARGARET TIVEY: Today, we're going 00:00:20.800 --> 00:00:23.360 align:middle line:84% to finish up talking about some of the inputs 00:00:23.360 --> 00:00:28.400 align:middle line:84% from rivers and hydrothermal vents. 00:00:28.400 --> 00:00:31.132 align:middle line:84% So what we're going to talk about today, 00:00:31.132 --> 00:00:32.840 align:middle line:84% we discussed the generation of vent fluid 00:00:32.840 --> 00:00:34.220 align:middle line:90% and the generation of rivers. 00:00:34.220 --> 00:00:36.220 align:middle line:84% So today, we're going to talk about what happens 00:00:36.220 --> 00:00:40.020 align:middle line:90% when these enter the oceans. 00:00:40.020 --> 00:00:43.520 align:middle line:90% So when rivers enter the oceans. 00:00:43.520 --> 00:00:48.120 align:middle line:84% And this is in terms of estuaries. 00:00:48.120 --> 00:00:50.900 align:middle line:84% So I'm going to spend the first third of the class on that. 00:00:50.900 --> 00:00:53.020 align:middle line:84% Then I'm going to talk some about groundwater. 00:00:53.020 --> 00:00:56.880 align:middle line:90% 00:00:56.880 --> 00:01:03.550 align:middle line:84% And how groundwater input can also affect estimates of fluxes 00:01:03.550 --> 00:01:06.310 align:middle line:84% from the continents into the oceans. 00:01:06.310 --> 00:01:11.830 align:middle line:84% And then finally, we're going to look at vent fluid entering 00:01:11.830 --> 00:01:18.430 align:middle line:84% the oceans, and this includes both formation of deposits, as 00:01:18.430 --> 00:01:21.910 align:middle line:90% well as of plumes. 00:01:21.910 --> 00:01:27.870 align:middle line:84% And while the deposits are left on the ocean floor and are 00:01:27.870 --> 00:01:33.340 align:middle line:84% a near-source issue, the plumes actually can rise 200 to 300 00:01:33.340 --> 00:01:37.210 align:middle line:84% meters above the sea floor, and you're at about 2,500 00:01:37.210 --> 00:01:40.830 align:middle line:84% meters' depth in the oceans, and you actually create a lot 00:01:40.830 --> 00:01:43.990 align:middle line:84% of mixing in a part of the ocean where you wouldn't normally 00:01:43.990 --> 00:01:47.310 align:middle line:84% suppose that you were going to have a large driver of mixing. 00:01:47.310 --> 00:01:51.190 align:middle line:84% So it has a lot of implications for physical oceanography 00:01:51.190 --> 00:01:53.190 align:middle line:84% and for chemical processes that are at a depth 00:01:53.190 --> 00:01:58.610 align:middle line:84% that we didn't really consider that important 30 years ago. 00:01:58.610 --> 00:01:59.130 align:middle line:90% OK. 00:01:59.130 --> 00:02:04.790 align:middle line:90% 00:02:04.790 --> 00:02:05.850 align:middle line:90% All right. 00:02:05.850 --> 00:02:09.250 align:middle line:84% So before I start, well, the first thing I want to talk about 00:02:09.250 --> 00:02:12.170 align:middle line:84% is that when rivers enter oceans, 00:02:12.170 --> 00:02:16.217 align:middle line:84% and when vent fluid enters oceans, you have contrasts. 00:02:16.217 --> 00:02:18.050 align:middle line:84% And you're going to have different contrasts 00:02:18.050 --> 00:02:19.590 align:middle line:84% for different ones of the fluids. 00:02:19.590 --> 00:02:22.650 align:middle line:84% For rivers, your dominant contrast versus the oceans 00:02:22.650 --> 00:02:24.790 align:middle line:90% is the change in salinity. 00:02:24.790 --> 00:02:27.850 align:middle line:90% 00:02:27.850 --> 00:02:31.610 align:middle line:84% So that's the key one for rivers. 00:02:31.610 --> 00:02:34.330 align:middle line:84% And the key one for vent fluids-- or there's two, 00:02:34.330 --> 00:02:37.130 align:middle line:84% really, is temperature, which actually 00:02:37.130 --> 00:02:39.550 align:middle line:84% creates a large buoyancy, and I'll get to that. 00:02:39.550 --> 00:02:43.750 align:middle line:84% So it's temperature and pH are your key differences. 00:02:43.750 --> 00:02:51.730 align:middle line:90% 00:02:51.730 --> 00:02:57.840 align:middle line:84% So going back, I want to remind you of what the rivers were like 00:02:57.840 --> 00:03:00.720 align:middle line:90% or how rivers were generated. 00:03:00.720 --> 00:03:07.680 align:middle line:84% We started with rainwater, and rock. 00:03:07.680 --> 00:03:10.680 align:middle line:90% You have weathering. 00:03:10.680 --> 00:03:16.000 align:middle line:84% You have congruent dissolution, discongruent dissolution. 00:03:16.000 --> 00:03:21.040 align:middle line:84% And the key thing is, you create a fluid that's 00:03:21.040 --> 00:03:30.460 align:middle line:84% carrying both dissolved ions, but also, you have particles. 00:03:30.460 --> 00:03:34.390 align:middle line:90% 00:03:34.390 --> 00:03:43.440 align:middle line:84% And on those particles, you have adsorbed metals. 00:03:43.440 --> 00:03:53.600 align:middle line:84% And you also have clays, iron oxyhydroxides, and humic matter. 00:03:53.600 --> 00:03:57.220 align:middle line:90% 00:03:57.220 --> 00:03:59.700 align:middle line:90% Put that up there. 00:03:59.700 --> 00:04:01.680 align:middle line:84% And those all have negative charges, 00:04:01.680 --> 00:04:05.880 align:middle line:84% and so those have ions associated with them as well, 00:04:05.880 --> 00:04:09.140 align:middle line:90% and we'll get into that. 00:04:09.140 --> 00:04:12.300 align:middle line:84% And we went briefly through-- at the very end of the river 00:04:12.300 --> 00:04:15.320 align:middle line:84% lecture, we went briefly through trace metal release 00:04:15.320 --> 00:04:17.040 align:middle line:90% when you have pH changes. 00:04:17.040 --> 00:04:19.380 align:middle line:84% So you can have subtle changes-- the pH of river water 00:04:19.380 --> 00:04:23.020 align:middle line:84% is going to vary from about 5 to about 7, is that right? 00:04:23.020 --> 00:04:23.580 align:middle line:90% Probably? 00:04:23.580 --> 00:04:26.020 align:middle line:90% Maybe a little more. 00:04:26.020 --> 00:04:29.560 align:middle line:84% And depending on what its pH is, that can have some effect, 00:04:29.560 --> 00:04:31.080 align:middle line:84% but those aren't the dominant ones. 00:04:31.080 --> 00:04:34.260 align:middle line:84% It really is this change in salinity. 00:04:34.260 --> 00:04:35.860 align:middle line:84% And then the last thing for the rivers 00:04:35.860 --> 00:04:43.140 align:middle line:84% was on top of all of this, you have the cyclic salts So 00:04:43.140 --> 00:04:44.680 align:middle line:90% that's just a review. 00:04:44.680 --> 00:04:52.810 align:middle line:90% 00:04:52.810 --> 00:04:54.770 align:middle line:90% OK. 00:04:54.770 --> 00:04:56.970 align:middle line:84% Hopefully you have your notes today. 00:04:56.970 --> 00:04:58.892 align:middle line:84% If not, you'll have to remember them 00:04:58.892 --> 00:05:00.850 align:middle line:84% because it's much easier to show these pictures 00:05:00.850 --> 00:05:03.032 align:middle line:84% as we go through the different types of estuaries. 00:05:03.032 --> 00:05:04.490 align:middle line:84% So essentially what you're doing is 00:05:04.490 --> 00:05:07.330 align:middle line:84% the river's coming down to the oceans, 00:05:07.330 --> 00:05:09.395 align:middle line:84% and it's going to enter, and any of you who've 00:05:09.395 --> 00:05:11.770 align:middle line:84% been near a river mouth, there's multiple different types 00:05:11.770 --> 00:05:12.770 align:middle line:90% of estuaries. 00:05:12.770 --> 00:05:14.330 align:middle line:84% And the key things that are going 00:05:14.330 --> 00:05:16.970 align:middle line:84% to affect the type of mixing in that estuary 00:05:16.970 --> 00:05:18.557 align:middle line:84% have to do with the discharge rate. 00:05:18.557 --> 00:05:20.390 align:middle line:84% If you've got a very high rate of discharge, 00:05:20.390 --> 00:05:21.630 align:middle line:84% you're going to have one style of mixing. 00:05:21.630 --> 00:05:24.327 align:middle line:84% And it also has to do with the depth that the estuaries at. 00:05:24.327 --> 00:05:26.410 align:middle line:84% And so we're going to discuss four different types 00:05:26.410 --> 00:05:29.410 align:middle line:90% of estuaries briefly. 00:05:29.410 --> 00:05:33.370 align:middle line:90% And in these figures-- 00:05:33.370 --> 00:05:35.030 align:middle line:84% and my apologies for the quality, 00:05:35.030 --> 00:05:38.850 align:middle line:84% they were Xeroxed initially I think about 15 years ago 00:05:38.850 --> 00:05:42.890 align:middle line:84% and have been written on and Xeroxed again. 00:05:42.890 --> 00:05:46.050 align:middle line:84% The first type is type A, and here, you have-- 00:05:46.050 --> 00:05:48.050 align:middle line:84% and it's where you have a shallow estuary 00:05:48.050 --> 00:05:49.030 align:middle line:90% with a small river. 00:05:49.030 --> 00:05:53.070 align:middle line:84% So you have a small discharge coming into a small estuary. 00:05:53.070 --> 00:05:54.850 align:middle line:84% You have a lot of these around here. 00:05:54.850 --> 00:06:02.310 align:middle line:84% And on this figure, what we have, 00:06:02.310 --> 00:06:07.070 align:middle line:84% you have four stations, 1, 2, 3, and 4. 00:06:07.070 --> 00:06:09.130 align:middle line:84% And then this just shows the mixing. 00:06:09.130 --> 00:06:10.430 align:middle line:90% So you have a station-- 00:06:10.430 --> 00:06:12.268 align:middle line:90% I mean the surface. 00:06:12.268 --> 00:06:12.810 align:middle line:90% What is that? 00:06:12.810 --> 00:06:15.120 align:middle line:84% I don't even know what that's supposed-- this is station 1, 2, 00:06:15.120 --> 00:06:15.620 align:middle line:90% 3, 4. 00:06:15.620 --> 00:06:18.370 align:middle line:84% But this is the surface, this is the bottom of the estuary, 00:06:18.370 --> 00:06:21.110 align:middle line:84% and this is simply showing the type of mixing that's going on. 00:06:21.110 --> 00:06:24.650 align:middle line:84% So when you have low discharge into a small estuary, 00:06:24.650 --> 00:06:26.910 align:middle line:90% you have a well-mixed-- 00:06:26.910 --> 00:06:31.370 align:middle line:84% well-vertically-mixed processes going on. 00:06:31.370 --> 00:06:33.430 align:middle line:84% So you're basically bringing fresh water out, 00:06:33.430 --> 00:06:35.350 align:middle line:84% and then you're going to have some tidal sloshing back 00:06:35.350 --> 00:06:35.850 align:middle line:90% and forth. 00:06:35.850 --> 00:06:37.950 align:middle line:84% But you end up-- what you want to do 00:06:37.950 --> 00:06:41.110 align:middle line:84% is take-- if you look at what the salinity profile is at each 00:06:41.110 --> 00:06:44.910 align:middle line:84% of these stations, you go over to the next side of your figure, 00:06:44.910 --> 00:06:48.960 align:middle line:84% and pretty much the salinity is not stratified at all. 00:06:48.960 --> 00:06:54.200 align:middle line:90% 00:06:54.200 --> 00:06:58.340 align:middle line:90% So these estuaries are-- 00:06:58.340 --> 00:07:01.020 align:middle line:84% they're dominated by tidal mixing. 00:07:01.020 --> 00:07:03.020 align:middle line:90% They're vertically well-mixed. 00:07:03.020 --> 00:07:04.560 align:middle line:90% And this is all in your notes. 00:07:04.560 --> 00:07:06.220 align:middle line:84% Probably not as bulleted as this, 00:07:06.220 --> 00:07:07.920 align:middle line:84% but they're vertically well-mixed. 00:07:07.920 --> 00:07:10.900 align:middle line:84% There's a net outward flow at all depths. 00:07:10.900 --> 00:07:14.220 align:middle line:84% And there's a seaward increase in salinity 00:07:14.220 --> 00:07:15.580 align:middle line:90% that's similar at all depths. 00:07:15.580 --> 00:07:22.780 align:middle line:90% 00:07:22.780 --> 00:07:24.800 align:middle line:84% Now you can also have the same thing going on, 00:07:24.800 --> 00:07:26.500 align:middle line:90% but you can end up with-- 00:07:26.500 --> 00:07:27.980 align:middle line:84% also in a shallow estuary, but you 00:07:27.980 --> 00:07:29.840 align:middle line:84% can end up with a two-layer system. 00:07:29.840 --> 00:07:33.495 align:middle line:90% 00:07:33.495 --> 00:07:36.120 align:middle line:84% And for this two-layer system, we have the same thing going on. 00:07:36.120 --> 00:07:39.780 align:middle line:84% First, let's look at what's happening with the flow. 00:07:39.780 --> 00:07:44.860 align:middle line:84% The low-salinity river water is flowing out on the upper part, 00:07:44.860 --> 00:07:47.800 align:middle line:84% seawater is flowing in on the lower part, 00:07:47.800 --> 00:07:49.980 align:middle line:84% and this is dominantly density-driven, 00:07:49.980 --> 00:07:52.000 align:middle line:84% but then you still have fairly-- you 00:07:52.000 --> 00:07:54.480 align:middle line:84% do have some mixing, some vertical mixing. 00:07:54.480 --> 00:07:57.240 align:middle line:84% And you end up-- if you take a look at the profiles across each 00:07:57.240 --> 00:08:01.560 align:middle line:84% of these stations, you end up with a slightly stratified 00:08:01.560 --> 00:08:04.280 align:middle line:90% salinity gradient. 00:08:04.280 --> 00:08:08.140 align:middle line:84% AUDIENCE: And what happens if an estuary is type A or type B? 00:08:08.140 --> 00:08:12.880 align:middle line:84% What would cause the inflow of seawater? 00:08:12.880 --> 00:08:14.840 align:middle line:84% MARGARET TIVEY: I think it has to do 00:08:14.840 --> 00:08:16.600 align:middle line:84% with the discharge-- a lot of it has 00:08:16.600 --> 00:08:18.140 align:middle line:90% to do with the discharge rate. 00:08:18.140 --> 00:08:19.120 align:middle line:90% If you have a-- 00:08:19.120 --> 00:08:20.747 align:middle line:84% correct me if I'm wrong if anybody-- 00:08:20.747 --> 00:08:22.580 align:middle line:84% I mean, if you have a high enough discharge, 00:08:22.580 --> 00:08:25.460 align:middle line:84% it's simply a mass-- you're pushing flow out, 00:08:25.460 --> 00:08:28.247 align:middle line:84% you're going to draw fluid back in. 00:08:28.247 --> 00:08:30.080 align:middle line:84% It's more of a physical-- you'd have to look 00:08:30.080 --> 00:08:31.640 align:middle line:90% at the physics of the system. 00:08:31.640 --> 00:08:35.080 align:middle line:84% AUDIENCE: Also, if you have a really shallow estuary, 00:08:35.080 --> 00:08:37.299 align:middle line:84% it gives you more turbulent mixing, 00:08:37.299 --> 00:08:39.043 align:middle line:84% and so you have better vertical mixing. 00:08:39.043 --> 00:08:39.960 align:middle line:90% MARGARET TIVEY: Right. 00:08:39.960 --> 00:08:43.440 align:middle line:84% But these were both for small-- for shallow. 00:08:43.440 --> 00:08:45.450 align:middle line:84% Both of these have fairly good vertical mixing, 00:08:45.450 --> 00:08:47.630 align:middle line:90% but you do have the-- 00:08:47.630 --> 00:08:49.730 align:middle line:84% but you can also-- and this is the other thing. 00:08:49.730 --> 00:08:51.630 align:middle line:84% You can also have the same estuary, 00:08:51.630 --> 00:08:55.630 align:middle line:84% have the different types at different times of the year. 00:08:55.630 --> 00:08:58.270 align:middle line:84% In fact-- so now I'm going to jump to the-- 00:08:58.270 --> 00:09:00.070 align:middle line:84% there's a type D, which I really think 00:09:00.070 --> 00:09:07.310 align:middle line:84% should be type C, because it's a variation on type B. 00:09:07.310 --> 00:09:10.190 align:middle line:84% And this is when you have a large river entering 00:09:10.190 --> 00:09:11.650 align:middle line:90% a shallow estuary. 00:09:11.650 --> 00:09:14.430 align:middle line:84% So again, this has to do with discharge rate. 00:09:14.430 --> 00:09:18.390 align:middle line:84% And here, you end up with a salt wedge. 00:09:18.390 --> 00:09:21.510 align:middle line:84% And as in the case before the surface waters 00:09:21.510 --> 00:09:28.658 align:middle line:84% have low salinity, seawater intrudes underneath as a wedge. 00:09:28.658 --> 00:09:30.450 align:middle line:84% And again, here's what the flow looks like. 00:09:30.450 --> 00:09:32.007 align:middle line:84% You have a higher rate of discharge, 00:09:32.007 --> 00:09:34.090 align:middle line:84% so the flow is coming out here, and this draws in, 00:09:34.090 --> 00:09:35.330 align:middle line:90% seawater is coming in here. 00:09:35.330 --> 00:09:37.190 align:middle line:84% And it's a mass balance of what's 00:09:37.190 --> 00:09:38.970 align:middle line:84% going to happen as the fluid flows. 00:09:38.970 --> 00:09:42.050 align:middle line:90% 00:09:42.050 --> 00:09:45.170 align:middle line:84% But here, instead of having a very well-stratified-- one 00:09:45.170 --> 00:09:48.230 align:middle line:84% of the key differences is you end up with this wedge. 00:09:48.230 --> 00:09:51.290 align:middle line:84% So out at station 4, the salinity 00:09:51.290 --> 00:09:56.090 align:middle line:84% increases at a much shallower depth, whereas at station 1, 00:09:56.090 --> 00:10:00.530 align:middle line:84% it's fairly fresh down towards the bottom. 00:10:00.530 --> 00:10:04.050 align:middle line:84% And there's an example in your notes about the Chesapeake Bay 00:10:04.050 --> 00:10:05.870 align:middle line:84% where at times of high discharge, 00:10:05.870 --> 00:10:09.410 align:middle line:84% you have a salt wedge, and at times of lower discharge, 00:10:09.410 --> 00:10:12.390 align:middle line:84% you have a stratified, a vertically stratified-- 00:10:12.390 --> 00:10:15.730 align:middle line:90% 00:10:15.730 --> 00:10:17.490 align:middle line:84% Now you also have the situation where 00:10:17.490 --> 00:10:22.170 align:middle line:84% you have a very deep estuary, and the example we're using here 00:10:22.170 --> 00:10:25.590 align:middle line:84% is that of a fjord, And you have a sill located here. 00:10:25.590 --> 00:10:27.370 align:middle line:90% And again, this shows the flow. 00:10:27.370 --> 00:10:31.890 align:middle line:84% The freshwater is flowing out at the upper levels. 00:10:31.890 --> 00:10:35.622 align:middle line:84% You have return of seawater at lower levels, 00:10:35.622 --> 00:10:37.330 align:middle line:84% but not at the deepest levels because you 00:10:37.330 --> 00:10:40.760 align:middle line:84% have the sill blocking those deep levels. 00:10:40.760 --> 00:10:45.360 align:middle line:84% But then what happens is you end up with higher salinity 00:10:45.360 --> 00:10:48.520 align:middle line:84% fluid basically pooling underneath behind the sill 00:10:48.520 --> 00:10:52.520 align:middle line:84% and it's not mixing up as often, and so you end up 00:10:52.520 --> 00:10:56.502 align:middle line:84% with a very highly stratified salinity gradient. 00:10:56.502 --> 00:10:58.960 align:middle line:84% And the reason we're talking about these salinity gradients 00:10:58.960 --> 00:11:00.920 align:middle line:90% is it's that-- 00:11:00.920 --> 00:11:06.000 align:middle line:84% is that the major change, the key property that 00:11:06.000 --> 00:11:10.000 align:middle line:84% is affecting whether or not you have non-conservative processes 00:11:10.000 --> 00:11:11.220 align:middle line:90% is this change of salinity. 00:11:11.220 --> 00:11:14.000 align:middle line:84% So it's important to know where the major change in salinity 00:11:14.000 --> 00:11:15.600 align:middle line:90% is occurring within the estuary. 00:11:15.600 --> 00:11:18.553 align:middle line:90% 00:11:18.553 --> 00:11:21.220 align:middle line:84% And so, again, this just shows a picture of the different types, 00:11:21.220 --> 00:11:23.012 align:middle line:84% and you'll have a lot of mixing, but you're 00:11:23.012 --> 00:11:24.840 align:middle line:84% mixing up in the shallower region 00:11:24.840 --> 00:11:28.000 align:middle line:84% because you have a sill which is preventing entrainment 00:11:28.000 --> 00:11:28.560 align:middle line:90% down here. 00:11:28.560 --> 00:11:36.120 align:middle line:90% 00:11:36.120 --> 00:11:36.860 align:middle line:90% All right. 00:11:36.860 --> 00:11:40.540 align:middle line:90% 00:11:40.540 --> 00:11:43.620 align:middle line:84% So now we get into what are the processes that 00:11:43.620 --> 00:11:46.500 align:middle line:90% are going to occur? 00:11:46.500 --> 00:11:49.240 align:middle line:84% The non-conservative processes that occur in estuaries. 00:11:49.240 --> 00:11:55.900 align:middle line:90% 00:11:55.900 --> 00:11:58.700 align:middle line:90% And we went over this last week. 00:11:58.700 --> 00:12:01.875 align:middle line:84% I'm going to show you a lot of diagrams, and most of these 00:12:01.875 --> 00:12:03.500 align:middle line:84% are going to be salinity diagrams where 00:12:03.500 --> 00:12:08.660 align:middle line:84% you have the seawater salinity here and freshwater salinity 00:12:08.660 --> 00:12:09.280 align:middle line:90% here. 00:12:09.280 --> 00:12:12.140 align:middle line:90% 00:12:12.140 --> 00:12:16.980 align:middle line:84% And if it's-- and you have some element here. 00:12:16.980 --> 00:12:19.700 align:middle line:84% And so if this is seawater salinity 00:12:19.700 --> 00:12:22.487 align:middle line:84% and this is freshwater salinity, if it's conservative mixing, 00:12:22.487 --> 00:12:24.320 align:middle line:84% you're simply going to have a straight line. 00:12:24.320 --> 00:12:28.820 align:middle line:90% 00:12:28.820 --> 00:12:30.660 align:middle line:84% And of course, if you have removal, 00:12:30.660 --> 00:12:34.460 align:middle line:84% you're going to be coming on this side of the straight line. 00:12:34.460 --> 00:12:38.010 align:middle line:84% So that's removal here and this is addition here. 00:12:38.010 --> 00:12:38.570 align:middle line:90% OK, so. 00:12:38.570 --> 00:12:41.610 align:middle line:84% You have a number of different things going on. 00:12:41.610 --> 00:12:43.570 align:middle line:84% A key one you have going on-- we talked 00:12:43.570 --> 00:12:46.060 align:middle line:90% about what's in the water. 00:12:46.060 --> 00:12:47.810 align:middle line:84% And one of the main things that's going on 00:12:47.810 --> 00:12:49.590 align:middle line:84% is you have particles in the water. 00:12:49.590 --> 00:12:52.190 align:middle line:90% So you have river colloids. 00:12:52.190 --> 00:12:56.210 align:middle line:90% 00:12:56.210 --> 00:12:59.990 align:middle line:84% And again, these are dominantly iron and humic substances. 00:12:59.990 --> 00:13:06.530 align:middle line:90% 00:13:06.530 --> 00:13:10.930 align:middle line:84% And what happens is the sea salt-- 00:13:10.930 --> 00:13:13.730 align:middle line:84% well, for all of these we talked about them 00:13:13.730 --> 00:13:16.150 align:middle line:84% having a negative charge on the outside, 00:13:16.150 --> 00:13:19.623 align:middle line:84% and this is described well in your notes. 00:13:19.623 --> 00:13:21.290 align:middle line:84% Basically, the colloids are electrically 00:13:21.290 --> 00:13:25.030 align:middle line:90% charged submicron particles. 00:13:25.030 --> 00:13:29.690 align:middle line:84% There's going to be the clays, the organic material, and some 00:13:29.690 --> 00:13:30.810 align:middle line:90% of the humic-- 00:13:30.810 --> 00:13:33.050 align:middle line:84% and some of the iron oxyhydroxides. 00:13:33.050 --> 00:13:35.140 align:middle line:84% So they're too small, they're very, very small, 00:13:35.140 --> 00:13:37.380 align:middle line:84% they're not going to undergo gravitational settling. 00:13:37.380 --> 00:13:39.300 align:middle line:84% And this negative charge on the outside, 00:13:39.300 --> 00:13:42.480 align:middle line:84% they're these electrostatic interactions 00:13:42.480 --> 00:13:45.463 align:middle line:84% which keep them in solution and help to keep them in solution. 00:13:45.463 --> 00:13:47.880 align:middle line:84% What happens is, when you bring in a higher-salinity fluid 00:13:47.880 --> 00:13:51.800 align:middle line:84% and you bring in salts, this neutralizes 00:13:51.800 --> 00:13:54.740 align:middle line:84% the electrostatic charges, the electric charges. 00:13:54.740 --> 00:13:57.200 align:middle line:84% So when the electric charges are neutralized, 00:13:57.200 --> 00:14:00.460 align:middle line:84% the colloids clump together, they aggregate, 00:14:00.460 --> 00:14:03.460 align:middle line:84% and then they're large enough to gravitate to settle by gravity. 00:14:03.460 --> 00:14:10.595 align:middle line:90% 00:14:10.595 --> 00:14:14.820 align:middle line:84% So basically, you are neutralizing salts. 00:14:14.820 --> 00:14:17.680 align:middle line:90% 00:14:17.680 --> 00:14:19.960 align:middle line:90% If I could write today. 00:14:19.960 --> 00:14:27.140 align:middle line:84% Salts neutralize the electric charges. 00:14:27.140 --> 00:14:31.880 align:middle line:90% 00:14:31.880 --> 00:14:40.040 align:middle line:84% Which allows aggregation, and then settling. 00:14:40.040 --> 00:14:44.460 align:middle line:90% 00:14:44.460 --> 00:14:47.960 align:middle line:84% AUDIENCE: You'll sometimes hear it described as flocculate. 00:14:47.960 --> 00:14:50.122 align:middle line:90% MARGARET TIVEY: Right. 00:14:50.122 --> 00:14:52.580 align:middle line:84% Which actually drives me crazy because flocculation, to me, 00:14:52.580 --> 00:14:54.337 align:middle line:84% is all fluffy and it stays in the water-- 00:14:54.337 --> 00:14:56.920 align:middle line:84% and it does for a little while, but then it gradually settles. 00:14:56.920 --> 00:15:02.100 align:middle line:90% 00:15:02.100 --> 00:15:04.740 align:middle line:84% So I'll put that as flocculation. 00:15:04.740 --> 00:15:07.470 align:middle line:90% There's two C's, right? 00:15:07.470 --> 00:15:09.140 align:middle line:90% As opposed to flagellate. 00:15:09.140 --> 00:15:09.740 align:middle line:90% Flocculation. 00:15:09.740 --> 00:15:10.280 align:middle line:90% OK. 00:15:10.280 --> 00:15:12.735 align:middle line:90% 00:15:12.735 --> 00:15:13.235 align:middle line:90% OK. 00:15:13.235 --> 00:15:14.840 align:middle line:90% And then second one. 00:15:14.840 --> 00:15:18.700 align:middle line:90% So that's the first key. 00:15:18.700 --> 00:15:26.220 align:middle line:84% The second one that's very important is desorption. 00:15:26.220 --> 00:15:27.940 align:middle line:84% And this is what I talked about-- 00:15:27.940 --> 00:15:30.930 align:middle line:84% we talked some about this going on within rivers with the pH 00:15:30.930 --> 00:15:33.750 align:middle line:84% changes because when the pH gets lower, 00:15:33.750 --> 00:15:36.770 align:middle line:90% you can desorb some of that-- 00:15:36.770 --> 00:15:39.610 align:middle line:84% when it gets higher, some of the trace metals 00:15:39.610 --> 00:15:44.210 align:middle line:90% desorb from particle surfaces. 00:15:44.210 --> 00:15:48.210 align:middle line:84% But the desorption in the river, you sometimes-- 00:15:48.210 --> 00:15:51.770 align:middle line:84% and Scott talked about this on an earlier lecture, 00:15:51.770 --> 00:15:53.810 align:middle line:84% and I talked about it as well, you 00:15:53.810 --> 00:15:58.650 align:middle line:84% can have calcium released from clay surfaces 00:15:58.650 --> 00:16:00.350 align:middle line:90% and replaced by sodium. 00:16:00.350 --> 00:16:04.130 align:middle line:90% 00:16:04.130 --> 00:16:07.490 align:middle line:90% You can also have radium. 00:16:07.490 --> 00:16:09.290 align:middle line:90% Can do the same thing. 00:16:09.290 --> 00:16:15.987 align:middle line:84% The third one-- the first two are 00:16:15.987 --> 00:16:18.070 align:middle line:84% the key ones that are going on right in the water. 00:16:18.070 --> 00:16:22.370 align:middle line:84% If you just took a batch of seawater and took a [INAUDIBLE] 00:16:22.370 --> 00:16:25.650 align:middle line:84% or desorption going on in terms of nonconservative processes. 00:16:25.650 --> 00:16:27.690 align:middle line:90% But there's a third one. 00:16:27.690 --> 00:16:29.650 align:middle line:84% When you can't explain it by these two, 00:16:29.650 --> 00:16:31.830 align:middle line:84% the other thing you can have happening 00:16:31.830 --> 00:16:34.930 align:middle line:84% are interactions with estuarine sediments. 00:16:34.930 --> 00:16:51.550 align:middle line:90% 00:16:51.550 --> 00:16:54.430 align:middle line:90% So basically, you have-- 00:16:54.430 --> 00:16:57.910 align:middle line:84% there's poor water gradients, and so you can-- if you actually 00:16:57.910 --> 00:16:59.550 align:middle line:84% stir up sediment on the bottom, you 00:16:59.550 --> 00:17:02.390 align:middle line:84% release pore fluids that are in the sediment. 00:17:02.390 --> 00:17:06.990 align:middle line:84% You also bring up sediments that have ions 00:17:06.990 --> 00:17:09.750 align:middle line:84% adsorbed on the outside, so you can release those. 00:17:09.750 --> 00:17:16.869 align:middle line:84% So really, the process is one of resuspension and interaction 00:17:16.869 --> 00:17:18.569 align:middle line:90% with the resuspended material. 00:17:18.569 --> 00:17:28.060 align:middle line:90% 00:17:28.060 --> 00:17:30.060 align:middle line:84% And the other one is release of pore waters. 00:17:30.060 --> 00:17:36.780 align:middle line:90% 00:17:36.780 --> 00:17:40.940 align:middle line:84% It's not just release, it can be released and exchanged. 00:17:40.940 --> 00:17:42.420 align:middle line:90% I know. 00:17:42.420 --> 00:17:43.060 align:middle line:90% OK. 00:17:43.060 --> 00:17:44.480 align:middle line:90% Put them all on one page. 00:17:44.480 --> 00:17:47.497 align:middle line:90% 00:17:47.497 --> 00:17:50.080 align:middle line:84% AUDIENCE: What do you guys think of pore waters in an estuary? 00:17:50.080 --> 00:17:53.608 align:middle line:90% 00:17:53.608 --> 00:17:56.140 align:middle line:84% Have you guys been to any of the little estuaries 00:17:56.140 --> 00:17:59.620 align:middle line:90% around here, the salt marshes? 00:17:59.620 --> 00:18:03.780 align:middle line:84% There's lots of what in an estuary? 00:18:03.780 --> 00:18:06.060 align:middle line:90% Lots of organic matter. 00:18:06.060 --> 00:18:07.598 align:middle line:84% So if you dig down into the mud-- 00:18:07.598 --> 00:18:09.640 align:middle line:84% it's a good field trip for you guys this weekend. 00:18:09.640 --> 00:18:12.140 align:middle line:84% Go to an estuary and dig down in the mud, 00:18:12.140 --> 00:18:14.877 align:middle line:84% you very quickly get to anoxic mud. 00:18:14.877 --> 00:18:17.460 align:middle line:84% MARGARET TIVEY: And you'll be able to tell because it'll start 00:18:17.460 --> 00:18:20.110 align:middle line:90% to smell really, really bad. 00:18:20.110 --> 00:18:21.860 align:middle line:84% AUDIENCE: And so that's one of the things, 00:18:21.860 --> 00:18:23.980 align:middle line:84% in pore waters from estuaries, is 00:18:23.980 --> 00:18:27.520 align:middle line:84% you're now releasing anoxic waters, which 00:18:27.520 --> 00:18:30.180 align:middle line:84% are going to have very different metal composition. 00:18:30.180 --> 00:18:33.560 align:middle line:84% So in some ways, there is some analogy between the pH-- 00:18:33.560 --> 00:18:34.520 align:middle line:90% MARGARET TIVEY: Right. 00:18:34.520 --> 00:18:37.400 align:middle line:84% AUDIENCE: pH changes that we're going to talk about at the end. 00:18:37.400 --> 00:18:38.275 align:middle line:90% MARGARET TIVEY: Yeah. 00:18:38.275 --> 00:18:42.535 align:middle line:90% 00:18:42.535 --> 00:18:44.160 align:middle line:84% Yeah, and in fact, at the very end when 00:18:44.160 --> 00:18:45.200 align:middle line:84% I'm talking about the vents, I'm going 00:18:45.200 --> 00:18:46.742 align:middle line:84% to talk about the microbial activity, 00:18:46.742 --> 00:18:49.810 align:middle line:84% but I'm not going to talk about it for the estuaries. 00:18:49.810 --> 00:18:53.080 align:middle line:84% AUDIENCE: We will talk about microbes more when you guys-- 00:18:53.080 --> 00:18:54.100 align:middle line:90% after the midterm. 00:18:54.100 --> 00:18:55.517 align:middle line:84% MARGARET TIVEY: Oh, is that right? 00:18:55.517 --> 00:18:56.720 align:middle line:90% OK. 00:18:56.720 --> 00:18:58.760 align:middle line:90% OK. 00:18:58.760 --> 00:18:59.260 align:middle line:90% All right. 00:18:59.260 --> 00:19:02.720 align:middle line:84% And then, speaking of bugs, this is the last one, 00:19:02.720 --> 00:19:06.040 align:middle line:90% which is you can have uptake-- 00:19:06.040 --> 00:19:07.560 align:middle line:84% did you read the notes this morning 00:19:07.560 --> 00:19:10.860 align:middle line:84% so that you could interject that properly when I needed it? 00:19:10.860 --> 00:19:12.430 align:middle line:90% Uptake by estuarine-- 00:19:12.430 --> 00:19:14.180 align:middle line:84% AUDIENCE: This one's burned into my brain. 00:19:14.180 --> 00:19:16.460 align:middle line:84% I think I have this class burned into my brain. 00:19:16.460 --> 00:19:20.760 align:middle line:84% MARGARET TIVEY: You have uptake by estuary and biota. 00:19:20.760 --> 00:19:22.800 align:middle line:90% And they can remove elements. 00:19:22.800 --> 00:19:24.290 align:middle line:90% Or this can remove elements. 00:19:24.290 --> 00:19:28.270 align:middle line:84% Presumably it can also release elements, but I think 00:19:28.270 --> 00:19:29.350 align:middle line:90% it's more the-- 00:19:29.350 --> 00:19:32.650 align:middle line:84% or not uptake, but the regurgitation. 00:19:32.650 --> 00:19:34.127 align:middle line:90% No, the-- 00:19:34.127 --> 00:19:35.710 align:middle line:84% AUDIENCE: I guess I'm kind of confused 00:19:35.710 --> 00:19:39.450 align:middle line:84% as to what the definition of conservative mixing is. 00:19:39.450 --> 00:19:40.950 align:middle line:84% MARGARET TIVEY: Oh, we'll get there. 00:19:40.950 --> 00:19:44.670 align:middle line:84% You're about you're about to see more graphs than you ever 00:19:44.670 --> 00:19:46.670 align:middle line:90% wanted to see. 00:19:46.670 --> 00:19:49.790 align:middle line:84% Basically, each of these processes 00:19:49.790 --> 00:19:52.910 align:middle line:90% either adds or removes material. 00:19:52.910 --> 00:19:56.110 align:middle line:84% If you mixed seawater and you mixed freshwater 00:19:56.110 --> 00:19:57.730 align:middle line:84% and you didn't do any of these things, 00:19:57.730 --> 00:20:01.190 align:middle line:84% then you'd see a perfect straight line like this, 00:20:01.190 --> 00:20:03.175 align:middle line:90% but we don't always. 00:20:03.175 --> 00:20:05.550 align:middle line:84% And for some elements, we do, and I'm going to go through 00:20:05.550 --> 00:20:07.650 align:middle line:84% those, and for some of them, we clearly don't. 00:20:07.650 --> 00:20:10.030 align:middle line:84% And so you have to explain why you're seeing 00:20:10.030 --> 00:20:11.310 align:middle line:90% the removal or the addition. 00:20:11.310 --> 00:20:14.590 align:middle line:84% And a key reason why you need to know that 00:20:14.590 --> 00:20:18.190 align:middle line:84% is because if you just take the iron value that's in rivers 00:20:18.190 --> 00:20:19.830 align:middle line:84% and say that all of that iron makes it 00:20:19.830 --> 00:20:22.835 align:middle line:84% all the way out into the ocean, you're wrong because a lot of it 00:20:22.835 --> 00:20:24.210 align:middle line:84% is left in the estuaries, and you 00:20:24.210 --> 00:20:26.850 align:middle line:84% have to try and figure out and try to quantify how much of that 00:20:26.850 --> 00:20:31.290 align:middle line:84% iron flocculates and settles within the estuary. 00:20:31.290 --> 00:20:36.250 align:middle line:84% So right now, we're going to show you a bunch of plots. 00:20:36.250 --> 00:20:38.930 align:middle line:84% AUDIENCE: That line, it doesn't-- 00:20:38.930 --> 00:20:41.690 align:middle line:84% I mean, that, to me, looks like you have something that's 00:20:41.690 --> 00:20:45.850 align:middle line:84% not in freshwater, and then you increase it 00:20:45.850 --> 00:20:49.130 align:middle line:90% as you go into saltwater. 00:20:49.130 --> 00:20:49.630 align:middle line:90% Whereas-- 00:20:49.630 --> 00:20:51.537 align:middle line:90% MARGARET TIVEY: Right, sorry. 00:20:51.537 --> 00:20:52.370 align:middle line:90% AUDIENCE: Well, no-- 00:20:52.370 --> 00:20:54.203 align:middle line:84% MARGARET TIVEY: I'm thinking-- you're right. 00:20:54.203 --> 00:20:56.410 align:middle line:90% This could be-- if it's high-- 00:20:56.410 --> 00:20:59.050 align:middle line:84% you're right, most of them are higher in freshwater and drop 00:20:59.050 --> 00:21:00.130 align:middle line:90% that way. 00:21:00.130 --> 00:21:00.810 align:middle line:84% AUDIENCE: It could go either way. 00:21:00.810 --> 00:21:02.518 align:middle line:84% MARGARET TIVEY: But it can go either way. 00:21:02.518 --> 00:21:04.050 align:middle line:90% But let me just-- 00:21:04.050 --> 00:21:07.930 align:middle line:84% it's easier to look at real data. 00:21:07.930 --> 00:21:10.492 align:middle line:84% The old confusing them by trying to be simple. 00:21:10.492 --> 00:21:11.950 align:middle line:84% AUDIENCE: But if it's conservative, 00:21:11.950 --> 00:21:13.110 align:middle line:84% wouldn't it just be a horizontal? 00:21:13.110 --> 00:21:14.860 align:middle line:84% MARGARET TIVEY: Well, let's just show you. 00:21:14.860 --> 00:21:16.050 align:middle line:90% I'll show you the first one. 00:21:16.050 --> 00:21:18.170 align:middle line:84% AUDIENCE: Then the concentration would be the same in the river-- 00:21:18.170 --> 00:21:19.087 align:middle line:90% MARGARET TIVEY: Boron. 00:21:19.087 --> 00:21:21.868 align:middle line:84% OK, most of these things-- in order 00:21:21.868 --> 00:21:24.160 align:middle line:84% to look at mixing, first of all, you have to figure out 00:21:24.160 --> 00:21:26.280 align:middle line:84% what to plot it against, and you have to be plotting it 00:21:26.280 --> 00:21:28.200 align:middle line:84% against something that you're pretty confident 00:21:28.200 --> 00:21:29.680 align:middle line:90% is conservative. 00:21:29.680 --> 00:21:33.260 align:middle line:84% And in general, the salinity is relatively conservative. 00:21:33.260 --> 00:21:34.920 align:middle line:84% You are not dumping large amounts 00:21:34.920 --> 00:21:39.580 align:middle line:84% of halite or large amounts of any sea salt into estuaries, 00:21:39.580 --> 00:21:42.360 align:middle line:84% and we know that, therefore, you can say either chloride 00:21:42.360 --> 00:21:45.500 align:middle line:84% or salinity tends to be conservative. 00:21:45.500 --> 00:21:47.960 align:middle line:84% And so an element that is conservative 00:21:47.960 --> 00:21:51.760 align:middle line:84% should plot on a straight line relative to that property. 00:21:51.760 --> 00:21:53.508 align:middle line:84% AUDIENCE: [INAUDIBLE] on the axes? 00:21:53.508 --> 00:21:55.800 align:middle line:84% MARGARET TIVEY: The axes, again, this is one of these-- 00:21:55.800 --> 00:22:00.720 align:middle line:90% this is-- I believe it's micro-- 00:22:00.720 --> 00:22:02.212 align:middle line:90% it's a concentration. 00:22:02.212 --> 00:22:03.420 align:middle line:90% It doesn't matter what it is. 00:22:03.420 --> 00:22:06.840 align:middle line:90% It's a concentration. 00:22:06.840 --> 00:22:08.220 align:middle line:90% Concentration unit. 00:22:08.220 --> 00:22:09.420 align:middle line:90% And this is salinity. 00:22:09.420 --> 00:22:16.242 align:middle line:90% 00:22:16.242 --> 00:22:17.700 align:middle line:84% And if you take a look at this, you 00:22:17.700 --> 00:22:23.380 align:middle line:84% can see that, within error, this boron is falling pretty much 00:22:23.380 --> 00:22:25.980 align:middle line:90% along a straight line. 00:22:25.980 --> 00:22:28.940 align:middle line:84% And so unless-- whether or not there's something actually going 00:22:28.940 --> 00:22:31.860 align:middle line:84% on here or actually going on here, 00:22:31.860 --> 00:22:33.982 align:middle line:84% you'd have to put the error bars on your analyzes 00:22:33.982 --> 00:22:35.440 align:middle line:84% and really try and figure that out, 00:22:35.440 --> 00:22:38.140 align:middle line:84% and we're going to get to issues with that in a little bit. 00:22:38.140 --> 00:22:39.820 align:middle line:84% But this is one where you clearly 00:22:39.820 --> 00:22:41.280 align:middle line:90% have conservative processes. 00:22:41.280 --> 00:22:43.780 align:middle line:84% You obviously can't be dumping a whole bunch of boron 00:22:43.780 --> 00:22:45.680 align:middle line:84% out unless you're dumping it with the salt, 00:22:45.680 --> 00:22:47.620 align:middle line:84% but we know that you're not dumping salt out. 00:22:47.620 --> 00:22:51.460 align:middle line:90% 00:22:51.460 --> 00:22:55.300 align:middle line:90% In contrast, here's iron. 00:22:55.300 --> 00:22:59.500 align:middle line:84% And again, it's simply concentration versus salinity. 00:22:59.500 --> 00:23:02.615 align:middle line:84% And so as you'll see, as Kristen pointed out, 00:23:02.615 --> 00:23:03.740 align:middle line:90% it can be either direction. 00:23:03.740 --> 00:23:05.700 align:middle line:84% Here, there's more boron in seawater 00:23:05.700 --> 00:23:07.940 align:middle line:84% than there is in freshwater; and here, there's 00:23:07.940 --> 00:23:12.940 align:middle line:84% more iron in the rivers than there is in the saltwater. 00:23:12.940 --> 00:23:15.573 align:middle line:84% AUDIENCE: That straight line is what it would be without-- 00:23:15.573 --> 00:23:16.490 align:middle line:90% MARGARET TIVEY: Right. 00:23:16.490 --> 00:23:19.410 align:middle line:84% And the straight line is what it would be if there 00:23:19.410 --> 00:23:22.150 align:middle line:84% wasn't-- and these little dots, which are much, 00:23:22.150 --> 00:23:25.170 align:middle line:84% much smaller than the big, fat pen line, 00:23:25.170 --> 00:23:27.583 align:middle line:90% are the actual measurements. 00:23:27.583 --> 00:23:29.250 align:middle line:84% And one of the things that they've noted 00:23:29.250 --> 00:23:34.890 align:middle line:84% is, in general, iron and humic substances 00:23:34.890 --> 00:23:39.850 align:middle line:84% tend to follow this type of curve pretty well, 00:23:39.850 --> 00:23:43.090 align:middle line:84% and that's dominantly from flocculation of material 00:23:43.090 --> 00:23:48.410 align:middle line:84% and dumping in estuaries and precipitation in estuaries. 00:23:48.410 --> 00:23:50.910 align:middle line:84% That's in contrast to some other things which I'll show you, 00:23:50.910 --> 00:23:54.330 align:middle line:90% which are much more complicated. 00:23:54.330 --> 00:23:55.950 align:middle line:90% Here, you have barium. 00:23:55.950 --> 00:23:58.970 align:middle line:84% And again, all of these are real profiles. 00:23:58.970 --> 00:24:03.170 align:middle line:84% Instead of trying to show you these idealistic profiles, 00:24:03.170 --> 00:24:05.950 align:middle line:84% these have all been taken directly out of the literature, 00:24:05.950 --> 00:24:07.850 align:middle line:84% and it's real data, which is why they're not 00:24:07.850 --> 00:24:11.575 align:middle line:90% all beautiful profiles. 00:24:11.575 --> 00:24:13.450 align:middle line:84% This is for barium, and there's a fair amount 00:24:13.450 --> 00:24:17.500 align:middle line:84% of barium in both the freshwater and in the saltwater, 00:24:17.500 --> 00:24:19.140 align:middle line:90% but they're subtly different. 00:24:19.140 --> 00:24:23.000 align:middle line:84% But then you see this very, very large increase in barium, 00:24:23.000 --> 00:24:25.100 align:middle line:84% and that is likely from desorption. 00:24:25.100 --> 00:24:30.380 align:middle line:90% 00:24:30.380 --> 00:24:33.600 align:middle line:84% And then they show some really nice fun ones 00:24:33.600 --> 00:24:36.480 align:middle line:90% where you have copper. 00:24:36.480 --> 00:24:39.100 align:middle line:84% And again, this is the kind of thing where you go out, 00:24:39.100 --> 00:24:42.440 align:middle line:84% and a lot of this work was being done in the '70s. 00:24:42.440 --> 00:24:44.600 align:middle line:84% And they were really trying to figure out-- 00:24:44.600 --> 00:24:48.280 align:middle line:84% both Ed Boyle and Ed [? Shakovets ?] in our program 00:24:48.280 --> 00:24:51.920 align:middle line:84% did a lot of this work trying to make sense of the data they were 00:24:51.920 --> 00:24:54.000 align:middle line:84% collecting and trying to quantify what's going on 00:24:54.000 --> 00:24:56.760 align:middle line:84% in the estuaries so we can better quantify river 00:24:56.760 --> 00:24:59.120 align:middle line:90% fluxes into the oceans. 00:24:59.120 --> 00:25:01.000 align:middle line:84% And here, you can see that copper, 00:25:01.000 --> 00:25:04.093 align:middle line:84% it looks like it's being added at very low salinity, 00:25:04.093 --> 00:25:05.760 align:middle line:84% but then as the salinity increases some, 00:25:05.760 --> 00:25:07.380 align:middle line:84% it looks like some is being removed, 00:25:07.380 --> 00:25:09.005 align:middle line:84% and then at higher salinities, it looks 00:25:09.005 --> 00:25:11.580 align:middle line:90% like some is being added again. 00:25:11.580 --> 00:25:14.998 align:middle line:84% So copper is one that is more complicated. 00:25:14.998 --> 00:25:17.540 align:middle line:84% And you'll find that a lot of these that are more complicated 00:25:17.540 --> 00:25:20.140 align:middle line:84% are ones that have multiple different valence states. 00:25:20.140 --> 00:25:21.820 align:middle line:84% And so there's a lot of redox processes 00:25:21.820 --> 00:25:24.300 align:middle line:84% that are going on at the same time that 00:25:24.300 --> 00:25:25.680 align:middle line:90% affect what's going on. 00:25:25.680 --> 00:25:28.740 align:middle line:90% 00:25:28.740 --> 00:25:30.560 align:middle line:90% And then manganese is another-- 00:25:30.560 --> 00:25:37.780 align:middle line:90% 00:25:37.780 --> 00:25:41.740 align:middle line:84% and here, you show, there's a large removal-- 00:25:41.740 --> 00:25:44.620 align:middle line:84% in this profile, there's a large removal at low salinity 00:25:44.620 --> 00:25:47.080 align:middle line:84% and a large addition at higher salinity. 00:25:47.080 --> 00:25:54.780 align:middle line:90% 00:25:54.780 --> 00:25:56.560 align:middle line:90% AUDIENCE: On the Iron plot-- 00:25:56.560 --> 00:25:57.060 align:middle line:90% sorry. 00:25:57.060 --> 00:25:59.180 align:middle line:84% MARGARET TIVEY: Is there a question up there? 00:25:59.180 --> 00:26:02.500 align:middle line:84% AUDIENCE: It might be the same one, I'm not sure. 00:26:02.500 --> 00:26:04.580 align:middle line:84% Can you just describe again why the barium 00:26:04.580 --> 00:26:06.080 align:middle line:90% has the shape that it does? 00:26:06.080 --> 00:26:06.872 align:middle line:90% MARGARET TIVEY: Oh. 00:26:06.872 --> 00:26:09.460 align:middle line:84% The barium has the shape that it does-- well, 00:26:09.460 --> 00:26:11.790 align:middle line:84% I'd have to go back to the paper to be sure why it is, 00:26:11.790 --> 00:26:14.170 align:middle line:84% but my suspicion is it's from desorption, 00:26:14.170 --> 00:26:18.050 align:middle line:84% so that you have barium on various particles 00:26:18.050 --> 00:26:19.590 align:middle line:84% that are coming into the estuaries, 00:26:19.590 --> 00:26:21.690 align:middle line:84% and then when it mixes with the salt, 00:26:21.690 --> 00:26:24.270 align:middle line:84% the barium is being-- there's exchange going on, 00:26:24.270 --> 00:26:26.450 align:middle line:84% and some other ion is replacing the barium 00:26:26.450 --> 00:26:30.220 align:middle line:84% and the barium is being released. 00:26:30.220 --> 00:26:33.393 align:middle line:84% Sort of like calcium and sodium exchange. 00:26:33.393 --> 00:26:35.810 align:middle line:84% AUDIENCE: Could you explain what was happening in the iron 00:26:35.810 --> 00:26:37.170 align:middle line:90% profile [INAUDIBLE]? 00:26:37.170 --> 00:26:38.850 align:middle line:84% MARGARET TIVEY: In the iron profile-- 00:26:38.850 --> 00:26:40.250 align:middle line:90% oh. 00:26:40.250 --> 00:26:43.890 align:middle line:84% AUDIENCE: On these plots, are you seeing just the free ion 00:26:43.890 --> 00:26:48.370 align:middle line:84% concentration or are you seeing also that in solution, but bound 00:26:48.370 --> 00:26:50.938 align:middle line:90% to some particle? 00:26:50.938 --> 00:26:52.730 align:middle line:84% MARGARET TIVEY: What you are measuring here 00:26:52.730 --> 00:26:54.522 align:middle line:84% when you do this-- and we'll get to it when 00:26:54.522 --> 00:26:57.210 align:middle line:84% we do the in-laboratory ones, is you're taking the fluid 00:26:57.210 --> 00:27:00.530 align:middle line:84% and you're taking the filtered portion, the less than 0.45 00:27:00.530 --> 00:27:02.450 align:middle line:84% micron portion of the fluid, you're 00:27:02.450 --> 00:27:05.610 align:middle line:84% analyzing that and coming up with the total iron. 00:27:05.610 --> 00:27:10.830 align:middle line:84% So this is looking at total iron in the 0.45-micron and less 00:27:10.830 --> 00:27:13.390 align:middle line:90% fraction, I believe. 00:27:13.390 --> 00:27:14.925 align:middle line:84% Yeah, that's what they usually do. 00:27:14.925 --> 00:27:16.550 align:middle line:84% You'd have to read each paper carefully 00:27:16.550 --> 00:27:18.175 align:middle line:84% to find out exactly what they're doing, 00:27:18.175 --> 00:27:20.350 align:middle line:84% but in general, that's what they do. 00:27:20.350 --> 00:27:23.230 align:middle line:84% So no, you're not looking at the iron that's on the large 00:27:23.230 --> 00:27:27.130 align:middle line:84% particles that are left on the 0.45-micron filter paper, 00:27:27.130 --> 00:27:30.830 align:middle line:84% but anything that can pass through that filter is included 00:27:30.830 --> 00:27:31.670 align:middle line:90% in this. 00:27:31.670 --> 00:27:35.130 align:middle line:84% AUDIENCE: So that would be truly dissolved free ions. 00:27:35.130 --> 00:27:37.377 align:middle line:84% It would be things that are complex in solution. 00:27:37.377 --> 00:27:38.710 align:middle line:90% MARGARET TIVEY: So it includes-- 00:27:38.710 --> 00:27:39.710 align:middle line:90% AUDIENCE: And colloids. 00:27:39.710 --> 00:27:40.627 align:middle line:90% MARGARET TIVEY: Right. 00:27:40.627 --> 00:27:43.230 align:middle line:90% 00:27:43.230 --> 00:27:52.070 align:middle line:84% So if we go back to this figure where 00:27:52.070 --> 00:27:54.950 align:middle line:84% we were looking at what was in the river water, 00:27:54.950 --> 00:27:58.550 align:middle line:84% once you get down below this 0.45 micron, 00:27:58.550 --> 00:28:00.850 align:middle line:84% it would include some of these clays as well. 00:28:00.850 --> 00:28:04.230 align:middle line:90% 00:28:04.230 --> 00:28:06.300 align:middle line:84% [? Katelyn, ?] did you have another question? 00:28:06.300 --> 00:28:08.220 align:middle line:84% AUDIENCE: Well, I was just wondering, 00:28:08.220 --> 00:28:10.220 align:middle line:84% it looks like in the iron profile, 00:28:10.220 --> 00:28:12.168 align:middle line:84% that it dips below the conservative-- 00:28:12.168 --> 00:28:12.960 align:middle line:90% MARGARET TIVEY: OK. 00:28:12.960 --> 00:28:13.720 align:middle line:90% AUDIENCE: --and rejoins it? 00:28:13.720 --> 00:28:14.140 align:middle line:90% MARGARET TIVEY: Perfect. 00:28:14.140 --> 00:28:15.160 align:middle line:90% Perfect question. 00:28:15.160 --> 00:28:20.220 align:middle line:84% Now one of the things is, is it one simple process going on? 00:28:20.220 --> 00:28:23.080 align:middle line:84% And these are all assuming that you only have two endmembers. 00:28:23.080 --> 00:28:26.302 align:middle line:84% You either you have a seawater endmember 00:28:26.302 --> 00:28:27.760 align:middle line:84% and you have a freshwater endmember 00:28:27.760 --> 00:28:29.360 align:middle line:84% and you don't have any other endmembers. 00:28:29.360 --> 00:28:31.152 align:middle line:84% And they're trying to simplify these things 00:28:31.152 --> 00:28:34.700 align:middle line:84% and come up with fairly straightforward processes 00:28:34.700 --> 00:28:36.600 align:middle line:84% that they can extrapolate globally 00:28:36.600 --> 00:28:40.820 align:middle line:84% so they can come up with a good idea of what global fluxes are. 00:28:40.820 --> 00:28:44.400 align:middle line:84% However, because of the type of thing you just talked about, 00:28:44.400 --> 00:28:47.060 align:middle line:84% [? Katelyn, ?] there's also concern about whether 00:28:47.060 --> 00:28:49.140 align:middle line:84% or not there might be a third component. 00:28:49.140 --> 00:28:51.780 align:middle line:90% And so there are some examples-- 00:28:51.780 --> 00:28:53.340 align:middle line:90% and this shows one here. 00:28:53.340 --> 00:28:55.200 align:middle line:90% This was work done by Ed Boyle. 00:28:55.200 --> 00:28:57.180 align:middle line:90% He went and looked back at-- 00:28:57.180 --> 00:29:00.500 align:middle line:84% this is a dissolved silica profile. 00:29:00.500 --> 00:29:04.660 align:middle line:84% And what could be-- it could be interpreted-- 00:29:04.660 --> 00:29:08.920 align:middle line:84% a lot of people would just interpret that as simple from 00:29:08.920 --> 00:29:13.260 align:middle line:84% either colloids or desorption-- no, not desorption, 00:29:13.260 --> 00:29:16.320 align:middle line:84% adsorption or something else, but what he attributed it 00:29:16.320 --> 00:29:23.280 align:middle line:84% to instead was a third component, a third mixing-- 00:29:23.280 --> 00:29:26.080 align:middle line:90% I mean a third endmember. 00:29:26.080 --> 00:29:27.560 align:middle line:84% And the reason for that is silica 00:29:27.560 --> 00:29:31.840 align:middle line:84% tends to be conservative when you mix, and it was very-- 00:29:31.840 --> 00:29:34.560 align:middle line:84% it was somewhat confusing why you 00:29:34.560 --> 00:29:37.040 align:middle line:84% would see this decrease-- because what 00:29:37.040 --> 00:29:38.380 align:middle line:90% would be the removal mechanism? 00:29:38.380 --> 00:29:40.020 align:middle line:90% Nobody had a removal mechanism. 00:29:40.020 --> 00:29:41.640 align:middle line:84% So his hypothesis is that there's 00:29:41.640 --> 00:29:47.320 align:middle line:84% a third source here of fluid that has a lower silica 00:29:47.320 --> 00:29:48.880 align:middle line:84% composition, and that you actually 00:29:48.880 --> 00:29:55.840 align:middle line:84% have conservative mixing between this source and the seawater 00:29:55.840 --> 00:29:59.920 align:middle line:84% source, and between this source and the river source. 00:29:59.920 --> 00:30:03.230 align:middle line:84% AUDIENCE: Can you point out what in the iron 00:30:03.230 --> 00:30:04.410 align:middle line:90% that you're talking about? 00:30:04.410 --> 00:30:04.870 align:middle line:90% MARGARET TIVEY: Oh. 00:30:04.870 --> 00:30:05.570 align:middle line:90% We're going to get there. 00:30:05.570 --> 00:30:07.320 align:middle line:84% We're going to get to-- that's messy data. 00:30:07.320 --> 00:30:10.470 align:middle line:84% Again, none of these have error bars on them. 00:30:10.470 --> 00:30:14.830 align:middle line:84% You also-- all you have to do is have one aggregate get 00:30:14.830 --> 00:30:20.390 align:middle line:84% into your bottle or have one colloid stick to the side 00:30:20.390 --> 00:30:21.290 align:middle line:90% of your container-- 00:30:21.290 --> 00:30:22.665 align:middle line:84% I mean, there's a lot-- there are 00:30:22.665 --> 00:30:25.110 align:middle line:84% a lot of things that can create noise in these data sets. 00:30:25.110 --> 00:30:29.690 align:middle line:90% 00:30:29.690 --> 00:30:31.190 align:middle line:84% But the key thing of this is for you 00:30:31.190 --> 00:30:33.898 align:middle line:84% to understand how to look at a profile 00:30:33.898 --> 00:30:36.190 align:middle line:84% and determine whether there's been removal or addition, 00:30:36.190 --> 00:30:39.390 align:middle line:84% and have some idea of what is likely causing 00:30:39.390 --> 00:30:41.090 align:middle line:90% that removal or the addition. 00:30:41.090 --> 00:30:45.150 align:middle line:90% And again, here, what confused-- 00:30:45.150 --> 00:30:48.490 align:middle line:84% the reason Ed Boyle went back to look at this was in general, 00:30:48.490 --> 00:30:51.590 align:middle line:84% he was finding in other profiles that silica was conservative, 00:30:51.590 --> 00:30:55.670 align:middle line:84% so an alternative interpretation of this 00:30:55.670 --> 00:30:59.187 align:middle line:84% is that you have a third source, fluid source. 00:30:59.187 --> 00:31:00.770 align:middle line:84% AUDIENCE: So, an example of that would 00:31:00.770 --> 00:31:02.873 align:middle line:84% be like two different ocean currents-- 00:31:02.873 --> 00:31:03.790 align:middle line:90% MARGARET TIVEY: Well-- 00:31:03.790 --> 00:31:05.325 align:middle line:90% AUDIENCE: --mixing with a river? 00:31:05.325 --> 00:31:06.450 align:middle line:90% MARGARET TIVEY: Or having-- 00:31:06.450 --> 00:31:08.330 align:middle line:84% AUDIENCE: --rivers and the coastal water or something 00:31:08.330 --> 00:31:09.090 align:middle line:90% like that? 00:31:09.090 --> 00:31:09.190 align:middle line:90% MARGARET TIVEY: Right. 00:31:09.190 --> 00:31:11.482 align:middle line:84% Either two rivers and a coastal water, or in this case, 00:31:11.482 --> 00:31:14.137 align:middle line:90% it was actually a shelf source. 00:31:14.137 --> 00:31:15.970 align:middle line:84% And we're going to get into groundwater flow 00:31:15.970 --> 00:31:18.230 align:middle line:84% as well, you can end up with groundwater flow source. 00:31:18.230 --> 00:31:25.370 align:middle line:90% 00:31:25.370 --> 00:31:28.230 align:middle line:84% Yes, he ended up with a-- for this one in particular, 00:31:28.230 --> 00:31:30.650 align:middle line:84% he had a river source, an open ocean source, and then 00:31:30.650 --> 00:31:32.690 align:middle line:90% an intermediate shelf source. 00:31:32.690 --> 00:31:36.545 align:middle line:84% I'm not sure what the source of the shelf source was, 00:31:36.545 --> 00:31:37.670 align:middle line:90% but it didn't go into that. 00:31:37.670 --> 00:31:39.090 align:middle line:84% But there was basically, you could 00:31:39.090 --> 00:31:42.390 align:middle line:84% go out-- so you then go out and sample that body of water, 00:31:42.390 --> 00:31:45.450 align:middle line:84% do some CTD casts and see if you can actually find that fluid out 00:31:45.450 --> 00:31:45.950 align:middle line:90% there. 00:31:45.950 --> 00:31:50.530 align:middle line:90% 00:31:50.530 --> 00:31:52.810 align:middle line:90% All right. 00:31:52.810 --> 00:31:55.090 align:middle line:84% Now, because of these complexities 00:31:55.090 --> 00:32:01.120 align:middle line:84% and some of the questions that [? Katelyn ?] was raising, 00:32:01.120 --> 00:32:03.240 align:middle line:84% you do have a concern and a problem 00:32:03.240 --> 00:32:06.080 align:middle line:90% when you have messy data. 00:32:06.080 --> 00:32:07.620 align:middle line:84% I talked about some of the issues. 00:32:07.620 --> 00:32:13.360 align:middle line:84% And here is a profile that shows copper and a mixing line. 00:32:13.360 --> 00:32:16.160 align:middle line:84% And the real question is, is this actually 00:32:16.160 --> 00:32:20.680 align:middle line:84% conservative mixing, or do you have some addition going on here 00:32:20.680 --> 00:32:22.620 align:middle line:84% and a little bit of addition going on there? 00:32:22.620 --> 00:32:25.800 align:middle line:84% What's really going on, and the data are very, very noisy. 00:32:25.800 --> 00:32:29.720 align:middle line:84% So Ed [? Shakovets ?] was one of the key people 00:32:29.720 --> 00:32:31.180 align:middle line:90% who helped develop this. 00:32:31.180 --> 00:32:33.780 align:middle line:84% You can also do your own mixing diagrams, 00:32:33.780 --> 00:32:34.860 align:middle line:90% this is all field data. 00:32:34.860 --> 00:32:36.440 align:middle line:90% So you can just take-- 00:32:36.440 --> 00:32:38.660 align:middle line:84% one option is to go out to the open ocean-- 00:32:38.660 --> 00:32:42.470 align:middle line:84% so go to this station, collect a bunch of this water, 00:32:42.470 --> 00:32:44.720 align:middle line:84% go to the river source, collect a bunch of that water, 00:32:44.720 --> 00:32:48.097 align:middle line:84% the fresh source, and then do the mixing in the lab after 00:32:48.097 --> 00:32:50.680 align:middle line:84% you've-- and you can either do this mixing depending on if you 00:32:50.680 --> 00:32:55.360 align:middle line:84% want to look at particle processes or colloid processes, 00:32:55.360 --> 00:32:58.780 align:middle line:84% you either filter or do it unfiltered. 00:32:58.780 --> 00:33:02.620 align:middle line:84% This is an example of an unfiltered river water. 00:33:02.620 --> 00:33:08.900 align:middle line:84% It was-- says unfiltered river water's 0.4 micron filters, 00:33:08.900 --> 00:33:12.080 align:middle line:84% which implies that it's filtered seawater, but anyway, 00:33:12.080 --> 00:33:14.780 align:middle line:90% you have to know what-- 00:33:14.780 --> 00:33:16.940 align:middle line:84% you would report in the paper exactly what you 00:33:16.940 --> 00:33:18.580 align:middle line:90% did with those fluids. 00:33:18.580 --> 00:33:24.460 align:middle line:84% But when they did that mixing experiment, 00:33:24.460 --> 00:33:26.960 align:middle line:84% this was the data they got from the mixing experiment, 00:33:26.960 --> 00:33:27.620 align:middle line:90% and it really-- 00:33:27.620 --> 00:33:30.460 align:middle line:84% AUDIENCE: I'm so confused as to the definition of conservative 00:33:30.460 --> 00:33:32.860 align:middle line:84% mixing versus non-conservative mixing because-- 00:33:32.860 --> 00:33:36.940 align:middle line:84% I mean, is it lab mixing or is it field mixing? 00:33:36.940 --> 00:33:40.020 align:middle line:84% Because some of the processes that we went over 00:33:40.020 --> 00:33:41.583 align:middle line:90% wouldn't happen in a lab. 00:33:41.583 --> 00:33:42.500 align:middle line:90% MARGARET TIVEY: Right. 00:33:42.500 --> 00:33:44.208 align:middle line:84% AUDIENCE: They're not happening in a lab, 00:33:44.208 --> 00:33:47.940 align:middle line:84% but they're happening in the field, what you call it, and-- 00:33:47.940 --> 00:33:50.460 align:middle line:84% MARGARET TIVEY: You call it non-conservative 00:33:50.460 --> 00:33:52.120 align:middle line:84% mixing no matter what's going on, 00:33:52.120 --> 00:33:54.480 align:middle line:84% but you have to identify the process that's going on. 00:33:54.480 --> 00:33:56.810 align:middle line:84% So you're right, this type of mixing experiment 00:33:56.810 --> 00:33:59.650 align:middle line:84% is only going to look at desorption-- chemical 00:33:59.650 --> 00:34:01.595 align:middle line:84% processes between those two bodies of water. 00:34:01.595 --> 00:34:03.970 align:middle line:84% It's not going to be considering any of this resuspension 00:34:03.970 --> 00:34:05.190 align:middle line:90% of sediment. 00:34:05.190 --> 00:34:06.250 align:middle line:90% AUDIENCE: Or biota-- 00:34:06.250 --> 00:34:08.409 align:middle line:84% MARGARET TIVEY: Or biota, right, unless there's-- 00:34:08.409 --> 00:34:10.010 align:middle line:84% well, except for microbial activity 00:34:10.010 --> 00:34:12.290 align:middle line:84% that's actually taking place in the water column-- 00:34:12.290 --> 00:34:14.850 align:middle line:84% in the two fluid samples that you've taken, 00:34:14.850 --> 00:34:17.050 align:middle line:84% but it's certainly not going to-- 00:34:17.050 --> 00:34:19.409 align:middle line:84% but for this, this is what they were looking at. 00:34:19.409 --> 00:34:22.622 align:middle line:84% They were trying to figure out, is copper being desorbed? 00:34:22.622 --> 00:34:24.330 align:middle line:84% Is there additional or is there a removal 00:34:24.330 --> 00:34:25.750 align:middle line:90% or is it being adsorbed? 00:34:25.750 --> 00:34:28.815 align:middle line:90% 00:34:28.815 --> 00:34:31.850 align:middle line:90% And then this was-- 00:34:31.850 --> 00:34:35.210 align:middle line:84% some other examples are in your notes. 00:34:35.210 --> 00:34:36.403 align:middle line:90% This is a much messier one. 00:34:36.403 --> 00:34:38.070 align:middle line:84% Take a look at that nice nickel profile. 00:34:38.070 --> 00:34:39.778 align:middle line:84% And I'm sure that scatter, in large part, 00:34:39.778 --> 00:34:45.788 align:middle line:84% has to do with errors on the analyzes. 00:34:45.788 --> 00:34:47.330 align:middle line:84% And then when they did it in the lab, 00:34:47.330 --> 00:34:49.870 align:middle line:84% they got a much cleaner data set. 00:34:49.870 --> 00:34:54.150 align:middle line:90% 00:34:54.150 --> 00:34:57.010 align:middle line:84% And similarly-- and then for calcium-- 00:34:57.010 --> 00:35:03.010 align:middle line:84% I mean for cadmium, the data were, again, ambiguous. 00:35:03.010 --> 00:35:08.750 align:middle line:84% For instance, is there actually a third source sitting here 00:35:08.750 --> 00:35:11.250 align:middle line:90% or is this simple desorption? 00:35:11.250 --> 00:35:13.270 align:middle line:84% And when they did the mixing calculation-- 00:35:13.270 --> 00:35:15.670 align:middle line:84% or the mixing experiments in the lab, 00:35:15.670 --> 00:35:17.950 align:middle line:84% they saw that you get this non-uniform-- 00:35:17.950 --> 00:35:21.710 align:middle line:84% or you get more desorption occurring at low salinity 00:35:21.710 --> 00:35:24.430 align:middle line:84% than at high salinity, but the entire profile 00:35:24.430 --> 00:35:25.990 align:middle line:90% can be explained by desorption. 00:35:25.990 --> 00:35:29.615 align:middle line:90% 00:35:29.615 --> 00:35:30.990 align:middle line:84% And again, all of these details-- 00:35:30.990 --> 00:35:33.350 align:middle line:84% I mean, there isn't-- you cannot just look at a data set 00:35:33.350 --> 00:35:35.730 align:middle line:84% and identify exactly what's going on. 00:35:35.730 --> 00:35:39.570 align:middle line:84% It's simply an interpretation of field data. 00:35:39.570 --> 00:35:42.563 align:middle line:84% And as shown by Ed Boyle, going back and reinterpreting one, 00:35:42.563 --> 00:35:45.230 align:middle line:84% the interpretations that are out there for all of these profiles 00:35:45.230 --> 00:35:49.050 align:middle line:90% are not necessarily 100% true. 00:35:49.050 --> 00:35:54.420 align:middle line:84% I mean, this is their hypothesis as to what's going on right now. 00:35:54.420 --> 00:35:58.560 align:middle line:84% Now there's a-- again in your notes, there's a generalization. 00:35:58.560 --> 00:36:04.720 align:middle line:84% This table gives you an idea of, in general, 00:36:04.720 --> 00:36:08.780 align:middle line:84% what happens with various ions, and in general, silica-- 00:36:08.780 --> 00:36:10.540 align:middle line:90% can you actually see that? 00:36:10.540 --> 00:36:11.400 align:middle line:90% Probably not. 00:36:11.400 --> 00:36:14.140 align:middle line:90% 00:36:14.140 --> 00:36:19.940 align:middle line:84% But silica, uranium, nickel, selenium, arsenic, a lot 00:36:19.940 --> 00:36:22.820 align:middle line:84% of these things in most rivers and estuaries 00:36:22.820 --> 00:36:28.740 align:middle line:84% are conservative except for manganese, actually, 00:36:28.740 --> 00:36:29.760 align:middle line:90% it can differ. 00:36:29.760 --> 00:36:30.667 align:middle line:90% It can be any. 00:36:30.667 --> 00:36:32.500 align:middle line:84% So this basically talks about whether or not 00:36:32.500 --> 00:36:37.460 align:middle line:84% there's input, namely addition, whether there's removal, 00:36:37.460 --> 00:36:39.680 align:middle line:84% or whether there tends to be conservative mixing, 00:36:39.680 --> 00:36:40.520 align:middle line:90% and it generalizes. 00:36:40.520 --> 00:36:42.420 align:middle line:84% And you'll see that copper, manganese, 00:36:42.420 --> 00:36:46.060 align:middle line:84% and a couple of other elements can have any one of the three 00:36:46.060 --> 00:36:50.490 align:middle line:84% going on depending on what estuary they're in. 00:36:50.490 --> 00:36:52.970 align:middle line:90% OK. 00:36:52.970 --> 00:36:55.450 align:middle line:90% AUDIENCE: What's that sign? 00:36:55.450 --> 00:36:59.410 align:middle line:84% The sign for the universal behavior that got 00:36:59.410 --> 00:37:00.630 align:middle line:90% cut off at the bottom? 00:37:00.630 --> 00:37:05.250 align:middle line:84% Is that underlined or a circle around the crop? 00:37:05.250 --> 00:37:07.830 align:middle line:84% MARGARET TIVEY: I believe it's the underlined-- you're right, 00:37:07.830 --> 00:37:10.250 align:middle line:90% that's-- sorry. 00:37:10.250 --> 00:37:13.490 align:middle line:90% That's universal behavior. 00:37:13.490 --> 00:37:16.830 align:middle line:84% And so you'll see that barium is almost always-- 00:37:16.830 --> 00:37:21.410 align:middle line:84% so barium, radium, cadmium are almost always added, 00:37:21.410 --> 00:37:26.110 align:middle line:84% whereas iron and beryllium and aluminum are almost-- 00:37:26.110 --> 00:37:29.690 align:middle line:84% and rare earth elements are almost always removed. 00:37:29.690 --> 00:37:30.395 align:middle line:90% And humics. 00:37:30.395 --> 00:37:31.770 align:middle line:84% AUDIENCE: Is that what the AG is? 00:37:31.770 --> 00:37:33.103 align:middle line:90% MARGARET TIVEY: The humic acids. 00:37:33.103 --> 00:37:39.330 align:middle line:90% 00:37:39.330 --> 00:37:40.830 align:middle line:90% OK. 00:37:40.830 --> 00:37:44.029 align:middle line:90% 00:37:44.029 --> 00:37:46.650 align:middle line:84% But you'll notice that it's not very many of these 00:37:46.650 --> 00:37:47.990 align:middle line:90% that have this universal. 00:37:47.990 --> 00:37:50.350 align:middle line:84% The following content is provided under a Creative 00:37:50.350 --> 00:37:51.710 align:middle line:90% Commons license. 00:37:51.710 --> 00:37:54.150 align:middle line:84% Your support will help MIT OpenCourseWare 00:37:54.150 --> 00:37:57.830 align:middle line:84% continue to offer high quality educational resources for free. 00:37:57.830 --> 00:38:01.070 align:middle line:84% To make a donation, or view additional materials 00:38:01.070 --> 00:38:05.030 align:middle line:84% from hundreds of MIT courses, visit MIT OpenCourseWare 00:38:05.030 --> 00:38:08.100 align:middle line:90% at ocw.mit.edu 00:38:08.100 --> 00:38:11.110 align:middle line:84% Today, we're going to finish up talking about some of the inputs 00:38:11.110 --> 00:38:16.150 align:middle line:84% from rivers and hydrothermal vents. 00:38:16.150 --> 00:38:18.882 align:middle line:84% So what we're going to talk about today, 00:38:18.882 --> 00:38:20.590 align:middle line:84% we discussed the generation of vent fluid 00:38:20.590 --> 00:38:22.010 align:middle line:90% and the generation of rivers. 00:38:22.010 --> 00:38:24.010 align:middle line:84% So today, we're going to talk about what happens 00:38:24.010 --> 00:38:27.770 align:middle line:90% when these enter the oceans. 00:38:27.770 --> 00:38:31.270 align:middle line:90% So when rivers enter the oceans. 00:38:31.270 --> 00:38:35.870 align:middle line:84% And this is in terms of estuaries. 00:38:35.870 --> 00:38:38.650 align:middle line:84% So I'm going to spend the first third of the class on that. 00:38:38.650 --> 00:38:44.630 align:middle line:84% Then I'm going to talk some about groundwater 00:38:44.630 --> 00:38:51.300 align:middle line:84% and how groundwater input can also affect estimates of fluxes 00:38:51.300 --> 00:38:54.060 align:middle line:84% from the continents into the oceans. 00:38:54.060 --> 00:38:59.580 align:middle line:84% And then finally, we're going to look at vent fluid entering 00:38:59.580 --> 00:39:01.580 align:middle line:90% the oceans. 00:39:01.580 --> 00:39:03.740 align:middle line:84% And this includes both the formation 00:39:03.740 --> 00:39:09.660 align:middle line:84% of deposits, as well as of plumes. 00:39:09.660 --> 00:39:15.300 align:middle line:84% And while the deposits are left on the ocean floor 00:39:15.300 --> 00:39:18.860 align:middle line:84% and are a near-source issue, the plumes 00:39:18.860 --> 00:39:23.060 align:middle line:84% actually can rise 200 to 300 meters above the sea floor. 00:39:23.060 --> 00:39:27.280 align:middle line:84% And you're at about 2,500 meters' depth in the oceans, 00:39:27.280 --> 00:39:30.260 align:middle line:84% and you actually create a lot of mixing in a part of the ocean 00:39:30.260 --> 00:39:32.580 align:middle line:84% where you wouldn't normally suppose that you were going 00:39:32.580 --> 00:39:35.060 align:middle line:84% to have a large driver of mixing. 00:39:35.060 --> 00:39:38.940 align:middle line:84% So it has a lot of implications for physical oceanography 00:39:38.940 --> 00:39:40.940 align:middle line:84% and for chemical processes that are at a depth 00:39:40.940 --> 00:39:46.380 align:middle line:84% that we didn't really consider that important 30 years ago. 00:39:46.380 --> 00:39:46.880 align:middle line:90% OK. 00:39:46.880 --> 00:39:52.440 align:middle line:90% 00:39:52.440 --> 00:39:53.600 align:middle line:90% All right. 00:39:53.600 --> 00:39:57.040 align:middle line:84% So before I start-- or the first thing I want to talk about 00:39:57.040 --> 00:40:01.200 align:middle line:84% is that when rivers enter oceans and when vent fluid enters 00:40:01.200 --> 00:40:03.967 align:middle line:90% oceans, you have contrasts. 00:40:03.967 --> 00:40:05.800 align:middle line:84% And you're going to have different contrasts 00:40:05.800 --> 00:40:07.340 align:middle line:84% for different ones of the fluids. 00:40:07.340 --> 00:40:10.400 align:middle line:84% For rivers, your dominant contrast versus the oceans 00:40:10.400 --> 00:40:12.540 align:middle line:90% is the change in salinity. 00:40:12.540 --> 00:40:15.560 align:middle line:90% 00:40:15.560 --> 00:40:19.400 align:middle line:84% So that's the key one for rivers. 00:40:19.400 --> 00:40:22.120 align:middle line:84% And the key one for vent fluids-- or there's two, 00:40:22.120 --> 00:40:24.880 align:middle line:84% really, it's temperature, which actually 00:40:24.880 --> 00:40:27.300 align:middle line:84% creates a large buoyancy, and I'll get to that. 00:40:27.300 --> 00:40:31.540 align:middle line:84% So it's temperature and pH are your key differences. 00:40:31.540 --> 00:40:39.520 align:middle line:90% 00:40:39.520 --> 00:40:45.590 align:middle line:84% So going back, I want to remind you of what the rivers were like 00:40:45.590 --> 00:40:48.470 align:middle line:90% or how rivers were generated. 00:40:48.470 --> 00:40:52.190 align:middle line:90% We started with rainwater. 00:40:52.190 --> 00:40:55.430 align:middle line:90% And rock. 00:40:55.430 --> 00:40:58.430 align:middle line:90% You have weathering. 00:40:58.430 --> 00:41:03.750 align:middle line:84% You have congruent dissolution, discongruent dissolution. 00:41:03.750 --> 00:41:08.790 align:middle line:84% And the key thing is you create a fluid that's 00:41:08.790 --> 00:41:18.210 align:middle line:84% carrying both dissolved ions, but also, you have particles. 00:41:18.210 --> 00:41:22.630 align:middle line:90% 00:41:22.630 --> 00:41:31.230 align:middle line:84% And on those particles, you have adsorbed metals. 00:41:31.230 --> 00:41:41.350 align:middle line:84% And you also have clays, iron oxyhydroxides, and humic matter. 00:41:41.350 --> 00:41:44.970 align:middle line:90% 00:41:44.970 --> 00:41:47.450 align:middle line:90% Put that up there. 00:41:47.450 --> 00:41:49.430 align:middle line:84% And those all have negative charges, 00:41:49.430 --> 00:41:53.630 align:middle line:84% and so those have ions associated with them as well, 00:41:53.630 --> 00:41:56.890 align:middle line:90% and we'll get into that. 00:41:56.890 --> 00:42:00.550 align:middle line:84% And we went briefly through, at the very end of the lecture, 00:42:00.550 --> 00:42:03.070 align:middle line:84% we went briefly through trace metal release 00:42:03.070 --> 00:42:04.790 align:middle line:90% when you have pH changes. 00:42:04.790 --> 00:42:07.130 align:middle line:84% So you can have subtle changes-- the pH of river water 00:42:07.130 --> 00:42:09.850 align:middle line:84% is going to vary from about 5 to about 7. 00:42:09.850 --> 00:42:10.810 align:middle line:90% Is that right? 00:42:10.810 --> 00:42:11.330 align:middle line:90% Probably? 00:42:11.330 --> 00:42:13.770 align:middle line:90% Maybe a little more. 00:42:13.770 --> 00:42:17.310 align:middle line:84% And depending on what its pH is, that can have some effect, 00:42:17.310 --> 00:42:18.830 align:middle line:84% but those aren't the dominant ones, 00:42:18.830 --> 00:42:22.010 align:middle line:84% it really is this change in salinity. 00:42:22.010 --> 00:42:23.650 align:middle line:84% And then the last thing for the rivers 00:42:23.650 --> 00:42:26.870 align:middle line:84% was on top of all of this, you have the cyclic salt-- 00:42:26.870 --> 00:42:29.770 align:middle line:90% the cyclic salts. 00:42:29.770 --> 00:42:30.770 align:middle line:90% OK. 00:42:30.770 --> 00:42:32.430 align:middle line:90% So that's just sort of a review. 00:42:32.430 --> 00:42:37.880 align:middle line:90% 00:42:37.880 --> 00:42:40.560 align:middle line:90% Do I need to show that? 00:42:40.560 --> 00:42:42.520 align:middle line:90% OK. 00:42:42.520 --> 00:42:44.720 align:middle line:84% Hopefully you have your notes today. 00:42:44.720 --> 00:42:46.642 align:middle line:84% If not, you'll have to remember them 00:42:46.642 --> 00:42:48.600 align:middle line:84% because it's much easier to show these pictures 00:42:48.600 --> 00:42:50.782 align:middle line:84% as we go through the different types of estuaries. 00:42:50.782 --> 00:42:52.240 align:middle line:84% So essentially what you're doing is 00:42:52.240 --> 00:42:56.380 align:middle line:84% a river's coming down to the oceans, and it's going to enter. 00:42:56.380 --> 00:42:58.500 align:middle line:84% And any of you who've been near a river mouth, 00:42:58.500 --> 00:43:00.660 align:middle line:84% there's multiple different types of estuaries. 00:43:00.660 --> 00:43:02.080 align:middle line:84% And the key things that are going 00:43:02.080 --> 00:43:04.720 align:middle line:84% to affect the type of mixing in that estuary 00:43:04.720 --> 00:43:06.347 align:middle line:84% have to do with the discharge rate. 00:43:06.347 --> 00:43:08.180 align:middle line:84% If you've got a very high rate of discharge, 00:43:08.180 --> 00:43:09.380 align:middle line:84% you're going to have one style of mixing. 00:43:09.380 --> 00:43:12.077 align:middle line:84% And it also has to do with the depth that the estuary's at. 00:43:12.077 --> 00:43:14.160 align:middle line:84% And so we're going to discuss four different types 00:43:14.160 --> 00:43:17.160 align:middle line:90% of estuaries briefly. 00:43:17.160 --> 00:43:21.120 align:middle line:90% And in these figures-- 00:43:21.120 --> 00:43:22.740 align:middle line:84% and my apologies for the quality, 00:43:22.740 --> 00:43:26.600 align:middle line:84% they were Xeroxed initially I think about 15 years ago 00:43:26.600 --> 00:43:29.020 align:middle line:84% and have been written on and Xeroxed again. 00:43:29.020 --> 00:43:33.800 align:middle line:84% So the first type is type A, and here, you have-- 00:43:33.800 --> 00:43:35.900 align:middle line:84% and it's where you have a shallow estuary 00:43:35.900 --> 00:43:36.880 align:middle line:90% with a small river. 00:43:36.880 --> 00:43:40.780 align:middle line:84% So you have a small discharge coming into a small estuary. 00:43:40.780 --> 00:43:42.560 align:middle line:84% You have a lot of these around here. 00:43:42.560 --> 00:43:45.960 align:middle line:84% And on this figure, what we have-- 00:43:45.960 --> 00:43:50.060 align:middle line:90% 00:43:50.060 --> 00:43:54.820 align:middle line:84% you have four stations, 1, 2, 3, and 4. 00:43:54.820 --> 00:43:56.880 align:middle line:84% And then this just shows the mixing. 00:43:56.880 --> 00:43:58.180 align:middle line:90% So you have a station-- 00:43:58.180 --> 00:44:00.018 align:middle line:90% I mean the surface. 00:44:00.018 --> 00:44:00.560 align:middle line:90% What is that? 00:44:00.560 --> 00:44:02.870 align:middle line:84% I don't even know what that's supposed-- this is station 1, 2, 00:44:02.870 --> 00:44:03.370 align:middle line:90% 3, 4. 00:44:03.370 --> 00:44:06.120 align:middle line:84% But this is the surface, this is the bottom of the estuary, 00:44:06.120 --> 00:44:08.960 align:middle line:84% and this is simply showing the type of mixing that's going on. 00:44:08.960 --> 00:44:12.400 align:middle line:84% So when you have low discharge into a small estuary, 00:44:12.400 --> 00:44:14.660 align:middle line:90% you have a well-mixed-- 00:44:14.660 --> 00:44:19.120 align:middle line:84% well-vertically-mixed processes going on. 00:44:19.120 --> 00:44:21.180 align:middle line:84% So you're basically bringing freshwater out. 00:44:21.180 --> 00:44:23.430 align:middle line:84% And then you're going to have some tidal sloshing back 00:44:23.430 --> 00:44:25.217 align:middle line:84% and forth, but you end up-- what you 00:44:25.217 --> 00:44:27.300 align:middle line:84% want to do is take a look at-- if you look at what 00:44:27.300 --> 00:44:30.420 align:middle line:84% the salinity profile is at each of these stations, 00:44:30.420 --> 00:44:32.660 align:middle line:84% you go over to the next side of your figure, 00:44:32.660 --> 00:44:36.710 align:middle line:84% and pretty much the salinity is not stratified at all. 00:44:36.710 --> 00:44:41.914 align:middle line:90% 00:44:41.914 --> 00:44:46.090 align:middle line:90% So these estuaries are-- 00:44:46.090 --> 00:44:48.770 align:middle line:84% they're dominated by tidal mixing, 00:44:48.770 --> 00:44:50.810 align:middle line:90% they're vertically well-mixed. 00:44:50.810 --> 00:44:52.310 align:middle line:90% And this is all in your notes. 00:44:52.310 --> 00:44:53.970 align:middle line:84% Probably not as bulleted as this, 00:44:53.970 --> 00:44:55.670 align:middle line:84% but they're vertically well-mixed, 00:44:55.670 --> 00:44:58.650 align:middle line:84% there's a net outward flow at all depths, 00:44:58.650 --> 00:45:01.970 align:middle line:84% and there's a seaward increase in salinity 00:45:01.970 --> 00:45:03.430 align:middle line:90% that's similar at all depths. 00:45:03.430 --> 00:45:10.340 align:middle line:90% 00:45:10.340 --> 00:45:12.550 align:middle line:84% Now you can also have the same thing going on, 00:45:12.550 --> 00:45:14.250 align:middle line:90% but you can end up with-- 00:45:14.250 --> 00:45:15.730 align:middle line:84% also in a shallow estuary, but you 00:45:15.730 --> 00:45:17.590 align:middle line:84% can end up with a two-layer system. 00:45:17.590 --> 00:45:21.245 align:middle line:90% 00:45:21.245 --> 00:45:23.870 align:middle line:84% And for this two-layer system, we have the same thing going on. 00:45:23.870 --> 00:45:27.530 align:middle line:84% First, let's look at what's happening with the flow. 00:45:27.530 --> 00:45:32.630 align:middle line:84% The low-salinity river water is flowing out on the upper part. 00:45:32.630 --> 00:45:35.550 align:middle line:84% Seawater is flowing in on the lower part. 00:45:35.550 --> 00:45:37.730 align:middle line:84% And this is dominantly density-driven, 00:45:37.730 --> 00:45:39.750 align:middle line:84% but then you still have fairly-- you 00:45:39.750 --> 00:45:42.230 align:middle line:84% do have some mixing, some vertical mixing. 00:45:42.230 --> 00:45:43.710 align:middle line:84% And you end up, if you take a look 00:45:43.710 --> 00:45:46.310 align:middle line:84% at the profiles across each of these stations, 00:45:46.310 --> 00:45:52.030 align:middle line:84% you end up with a slightly stratified salinity gradient. 00:45:52.030 --> 00:45:55.910 align:middle line:84% AUDIENCE: And what happens if an estuary is type A or type B? 00:45:55.910 --> 00:46:00.630 align:middle line:84% What would cause the inflow of seawater? 00:46:00.630 --> 00:46:02.590 align:middle line:84% MARGARET TIVEY: I think it has to do 00:46:02.590 --> 00:46:04.350 align:middle line:84% with the discharge-- a lot of it has 00:46:04.350 --> 00:46:05.890 align:middle line:90% to do with the discharge rate. 00:46:05.890 --> 00:46:08.497 align:middle line:84% If you have a-- correct me if I'm wrong, if anybody-- 00:46:08.497 --> 00:46:10.330 align:middle line:84% I mean, if you have a high enough discharge, 00:46:10.330 --> 00:46:13.210 align:middle line:84% it's simply a mass-- you're pushing flow out, 00:46:13.210 --> 00:46:16.230 align:middle line:84% you're going to draw fluid back in. 00:46:16.230 --> 00:46:17.250 align:middle line:90% It's more of a-- 00:46:17.250 --> 00:46:19.250 align:middle line:84% you'd have to look at the physics of the system. 00:46:19.250 --> 00:46:22.830 align:middle line:84% AUDIENCE: Also, if you have a really shallow estuary, 00:46:22.830 --> 00:46:24.593 align:middle line:84% it gives you more turbulent mixing-- 00:46:24.593 --> 00:46:25.510 align:middle line:90% MARGARET TIVEY: Right. 00:46:25.510 --> 00:46:27.750 align:middle line:84% AUDIENCE: --better vertical mixing, too. 00:46:27.750 --> 00:46:29.292 align:middle line:84% MARGARET TIVEY: Right, but these were 00:46:29.292 --> 00:46:31.242 align:middle line:90% both for small-- for shallow. 00:46:31.242 --> 00:46:33.200 align:middle line:84% Both of these have fairly good vertical mixing, 00:46:33.200 --> 00:46:35.380 align:middle line:90% but you do have the-- 00:46:35.380 --> 00:46:37.480 align:middle line:84% but you can also-- and this is the other thing, 00:46:37.480 --> 00:46:41.420 align:middle line:84% you can also have the same estuary have the different types 00:46:41.420 --> 00:46:43.380 align:middle line:90% at different times of the year. 00:46:43.380 --> 00:46:46.740 align:middle line:84% In fact-- so now I'm going to jump to the-- there's a type 00:46:46.740 --> 00:46:51.300 align:middle line:84% D, which I really think should be type C because it's one-- 00:46:51.300 --> 00:46:55.340 align:middle line:84% it's a variation on type B. And this 00:46:55.340 --> 00:46:59.400 align:middle line:84% is when you have a large river entering a shallow estuary. 00:46:59.400 --> 00:47:02.180 align:middle line:84% So again, this has to do with discharge rate. 00:47:02.180 --> 00:47:06.140 align:middle line:84% And here, you end up with a salt wedge. 00:47:06.140 --> 00:47:09.260 align:middle line:84% And as in the case before the surface waters 00:47:09.260 --> 00:47:16.408 align:middle line:84% have low salinity, seawater intrudes underneath as a wedge. 00:47:16.408 --> 00:47:18.200 align:middle line:84% And again, here's what the flow looks like. 00:47:18.200 --> 00:47:19.757 align:middle line:84% You have a higher rate of discharge, 00:47:19.757 --> 00:47:21.840 align:middle line:84% so the flow is coming out here, and this draws in, 00:47:21.840 --> 00:47:23.040 align:middle line:90% seawater is coming in here. 00:47:23.040 --> 00:47:24.940 align:middle line:84% And it's a mass balance of what's 00:47:24.940 --> 00:47:26.720 align:middle line:84% going to happen as the fluid flows. 00:47:26.720 --> 00:47:29.840 align:middle line:90% 00:47:29.840 --> 00:47:32.880 align:middle line:84% But here, instead of having a very well-stratified-- one 00:47:32.880 --> 00:47:35.980 align:middle line:84% of the key differences is, you end up with this wedge. 00:47:35.980 --> 00:47:39.080 align:middle line:84% So out at station 4, the salinity 00:47:39.080 --> 00:47:43.840 align:middle line:84% increases at a much shallower depth, whereas at station 1, 00:47:43.840 --> 00:47:48.280 align:middle line:84% it's fairly fresh down towards the bottom. 00:47:48.280 --> 00:47:51.800 align:middle line:84% And there's an example in your notes about the Chesapeake Bay 00:47:51.800 --> 00:47:53.620 align:middle line:84% where at times of high discharge, 00:47:53.620 --> 00:47:57.160 align:middle line:84% you have a salt wedge, and at times of lower discharge, 00:47:57.160 --> 00:48:00.140 align:middle line:84% you have a stratified, a vertically stratified-- 00:48:00.140 --> 00:48:03.440 align:middle line:90% 00:48:03.440 --> 00:48:05.240 align:middle line:84% Now you also have the situation where 00:48:05.240 --> 00:48:08.640 align:middle line:90% you have a very deep estuary. 00:48:08.640 --> 00:48:11.140 align:middle line:84% And the example we're using here is that of a fjord, 00:48:11.140 --> 00:48:13.340 align:middle line:84% and you have a sill located here. 00:48:13.340 --> 00:48:15.120 align:middle line:90% And again, this shows the flow. 00:48:15.120 --> 00:48:19.640 align:middle line:84% The freshwater is flowing out at the upper levels. 00:48:19.640 --> 00:48:23.332 align:middle line:84% You have return of seawater at lower levels, 00:48:23.332 --> 00:48:25.040 align:middle line:84% but not at the deepest levels because you 00:48:25.040 --> 00:48:28.550 align:middle line:84% have the sill blocking those deep levels. 00:48:28.550 --> 00:48:31.510 align:middle line:84% But then what happens is, you end up 00:48:31.510 --> 00:48:34.430 align:middle line:84% with higher-salinity fluid basically pooling 00:48:34.430 --> 00:48:39.510 align:middle line:84% underneath behind the sill, and it's not mixing up as often. 00:48:39.510 --> 00:48:42.830 align:middle line:84% And so you end up with a very highly stratified salinity 00:48:42.830 --> 00:48:44.212 align:middle line:90% gradient. 00:48:44.212 --> 00:48:46.670 align:middle line:84% And the reason we're talking about these salinity gradients 00:48:46.670 --> 00:48:48.670 align:middle line:90% is it's that-- 00:48:48.670 --> 00:48:53.750 align:middle line:84% is that the major change, the key property that 00:48:53.750 --> 00:48:57.692 align:middle line:84% is affecting whether or not you have non-conservative processes 00:48:57.692 --> 00:48:59.150 align:middle line:84% is this change of salinity, so it's 00:48:59.150 --> 00:49:01.750 align:middle line:84% important to know where the major change in salinity 00:49:01.750 --> 00:49:04.990 align:middle line:90% is occurring within the estuary. 00:49:04.990 --> 00:49:08.638 align:middle line:84% And so, again, this just shows a picture of the different types. 00:49:08.638 --> 00:49:10.430 align:middle line:84% And you'll have a lot of mixing, but you're 00:49:10.430 --> 00:49:12.590 align:middle line:84% mixing up in the shallower region 00:49:12.590 --> 00:49:15.790 align:middle line:84% because you have a sill which is preventing entrainment 00:49:15.790 --> 00:49:16.410 align:middle line:90% down here. 00:49:16.410 --> 00:49:23.870 align:middle line:90% 00:49:23.870 --> 00:49:24.680 align:middle line:90% All right. 00:49:24.680 --> 00:49:28.300 align:middle line:90% 00:49:28.300 --> 00:49:31.340 align:middle line:84% So now we get into what are the processes that 00:49:31.340 --> 00:49:35.660 align:middle line:84% are going to occur, the non-conservative processes that 00:49:35.660 --> 00:49:37.000 align:middle line:90% occur in estuaries? 00:49:37.000 --> 00:49:43.620 align:middle line:90% 00:49:43.620 --> 00:49:46.460 align:middle line:90% And we went over this last week. 00:49:46.460 --> 00:49:48.885 align:middle line:84% I'm going to show you a lot of diagrams. 00:49:48.885 --> 00:49:51.260 align:middle line:84% And most of these are going to be salinity diagrams where 00:49:51.260 --> 00:49:56.460 align:middle line:84% you have the seawater salinity here and freshwater salinity 00:49:56.460 --> 00:49:57.040 align:middle line:90% here. 00:49:57.040 --> 00:49:59.900 align:middle line:90% 00:49:59.900 --> 00:50:04.740 align:middle line:84% And if it's-- and you have some element here. 00:50:04.740 --> 00:50:07.460 align:middle line:84% And so if this is seawater salinity 00:50:07.460 --> 00:50:10.247 align:middle line:84% and this is freshwater salinity, if it's conservative mixing, 00:50:10.247 --> 00:50:12.080 align:middle line:84% you're simply going to have a straight line. 00:50:12.080 --> 00:50:15.460 align:middle line:90% 00:50:15.460 --> 00:50:18.420 align:middle line:84% And of course if you have removal, 00:50:18.420 --> 00:50:22.220 align:middle line:84% you're going to be coming on this side of the straight line. 00:50:22.220 --> 00:50:25.540 align:middle line:84% So that's removal here, and this is addition here. 00:50:25.540 --> 00:50:26.040 align:middle line:90% OK. 00:50:26.040 --> 00:50:29.360 align:middle line:84% So you have a number of different things going on. 00:50:29.360 --> 00:50:31.320 align:middle line:84% A key one you have going on-- we talked 00:50:31.320 --> 00:50:33.810 align:middle line:90% about what's in the water. 00:50:33.810 --> 00:50:35.560 align:middle line:84% And one of the main things that's going on 00:50:35.560 --> 00:50:37.340 align:middle line:84% is you have particles in the water. 00:50:37.340 --> 00:50:39.980 align:middle line:90% So you have river colloids. 00:50:39.980 --> 00:50:44.000 align:middle line:90% 00:50:44.000 --> 00:50:47.740 align:middle line:84% And again, these are dominantly iron and humic substances. 00:50:47.740 --> 00:50:54.240 align:middle line:90% 00:50:54.240 --> 00:50:58.680 align:middle line:84% And what happens is the sea salt-- 00:50:58.680 --> 00:51:00.400 align:middle line:84% well, for all of these, we talked 00:51:00.400 --> 00:51:03.940 align:middle line:84% about them having a negative charge on the outside, 00:51:03.940 --> 00:51:07.413 align:middle line:84% and this is described well in your notes. 00:51:07.413 --> 00:51:09.080 align:middle line:84% Basically, the colloids are electrically 00:51:09.080 --> 00:51:12.820 align:middle line:90% charged submicron particles. 00:51:12.820 --> 00:51:17.440 align:middle line:84% There's going to be the clays, the organic material, and some 00:51:17.440 --> 00:51:18.520 align:middle line:90% of the humic-- 00:51:18.520 --> 00:51:20.830 align:middle line:84% and some of the iron oxyhydroxides. 00:51:20.830 --> 00:51:22.890 align:middle line:84% So they're too small, they're very, very small, 00:51:22.890 --> 00:51:25.090 align:middle line:84% they're not going to undergo gravitational settling. 00:51:25.090 --> 00:51:27.050 align:middle line:84% And this negative charge on the outside, 00:51:27.050 --> 00:51:30.230 align:middle line:84% there are these electrostatic interactions 00:51:30.230 --> 00:51:33.213 align:middle line:84% which keep them in solution and help to keep them in solution. 00:51:33.213 --> 00:51:35.630 align:middle line:84% What happens is, when you bring in a higher-salinity fluid 00:51:35.630 --> 00:51:39.550 align:middle line:84% and you bring in salts, this neutralizes 00:51:39.550 --> 00:51:42.490 align:middle line:84% the electrostatic charges, the electric charges. 00:51:42.490 --> 00:51:44.950 align:middle line:84% So when the electric charges are neutralized, 00:51:44.950 --> 00:51:48.210 align:middle line:84% the colloids clump together, they aggregate, 00:51:48.210 --> 00:51:51.210 align:middle line:84% and then they're large enough to gravitate to settle by gravity. 00:51:51.210 --> 00:51:58.345 align:middle line:90% 00:51:58.345 --> 00:52:02.570 align:middle line:84% So basically, you are neutralizing salts. 00:52:02.570 --> 00:52:05.430 align:middle line:90% 00:52:05.430 --> 00:52:07.670 align:middle line:90% If I could write today. 00:52:07.670 --> 00:52:21.730 align:middle line:84% Salts neutralize the electric charges, which allows 00:52:21.730 --> 00:52:27.830 align:middle line:90% aggregation, and then settling. 00:52:27.830 --> 00:52:32.210 align:middle line:90% 00:52:32.210 --> 00:52:35.710 align:middle line:84% AUDIENCE: You'll sometimes hear it described as flocculate. 00:52:35.710 --> 00:52:37.872 align:middle line:90% MARGARET TIVEY: Right. 00:52:37.872 --> 00:52:40.330 align:middle line:84% Which actually drives me crazy because flocculation, to me, 00:52:40.330 --> 00:52:42.087 align:middle line:84% is all fluffy and it stays in the water, 00:52:42.087 --> 00:52:44.670 align:middle line:84% and it does for a little while, but then it gradually settles. 00:52:44.670 --> 00:52:49.810 align:middle line:90% 00:52:49.810 --> 00:52:52.490 align:middle line:84% So I'll put that as flocculation. 00:52:52.490 --> 00:52:55.220 align:middle line:90% There's two C's, right? 00:52:55.220 --> 00:52:56.890 align:middle line:90% As opposed to flagellate. 00:52:56.890 --> 00:52:57.530 align:middle line:90% Flocculation. 00:52:57.530 --> 00:53:00.260 align:middle line:90% OK. 00:53:00.260 --> 00:53:00.760 align:middle line:90% OK. 00:53:00.760 --> 00:53:02.590 align:middle line:90% And then the second one. 00:53:02.590 --> 00:53:06.450 align:middle line:90% So that's the first key. 00:53:06.450 --> 00:53:14.010 align:middle line:84% The second one that's very important is desorption. 00:53:14.010 --> 00:53:15.690 align:middle line:84% And this is what I talked about-- 00:53:15.690 --> 00:53:18.680 align:middle line:84% we talked some about this going on within rivers with the pH 00:53:18.680 --> 00:53:21.460 align:middle line:84% changes, because when the pH gets lower, 00:53:21.460 --> 00:53:24.480 align:middle line:90% you can desorb some of that-- 00:53:24.480 --> 00:53:27.320 align:middle line:84% when it gets higher, some of the trace metals 00:53:27.320 --> 00:53:31.960 align:middle line:90% desorb from particle surfaces. 00:53:31.960 --> 00:53:36.560 align:middle line:84% But the desorption in the river, you sometimes-- and Scott 00:53:36.560 --> 00:53:39.520 align:middle line:84% talked about this on an earlier lecture, 00:53:39.520 --> 00:53:41.560 align:middle line:84% and I talked about it as well, you 00:53:41.560 --> 00:53:46.400 align:middle line:84% can have calcium released from clay surfaces 00:53:46.400 --> 00:53:48.100 align:middle line:90% and replaced by sodium. 00:53:48.100 --> 00:53:51.880 align:middle line:90% 00:53:51.880 --> 00:53:55.200 align:middle line:90% You can also have radium. 00:53:55.200 --> 00:53:57.040 align:middle line:90% Can do the same thing. 00:53:57.040 --> 00:54:03.737 align:middle line:84% The third one-- the first two are 00:54:03.737 --> 00:54:05.820 align:middle line:84% the key ones that are going on right in the water. 00:54:05.820 --> 00:54:10.120 align:middle line:84% If you just took a batch of seawater and took a [INAUDIBLE] 00:54:10.120 --> 00:54:13.400 align:middle line:84% or desorption going on in terms of nonconservative processes. 00:54:13.400 --> 00:54:15.500 align:middle line:90% But there's a third one. 00:54:15.500 --> 00:54:17.237 align:middle line:84% When you can't explain it by these two, 00:54:17.237 --> 00:54:18.820 align:middle line:84% the other thing you can have happening 00:54:18.820 --> 00:54:22.680 align:middle line:84% is our interactions with estuarine sediments. 00:54:22.680 --> 00:54:39.300 align:middle line:90% 00:54:39.300 --> 00:54:42.180 align:middle line:90% So basically, you have-- 00:54:42.180 --> 00:54:45.660 align:middle line:84% there's pore water gradients, and so you can-- if you actually 00:54:45.660 --> 00:54:47.300 align:middle line:84% stir up sediment on the bottom, you 00:54:47.300 --> 00:54:50.140 align:middle line:84% release pore fluids that are in the sediment. 00:54:50.140 --> 00:54:54.740 align:middle line:84% You also bring up sediments that have ions 00:54:54.740 --> 00:54:57.540 align:middle line:84% adsorbed on the outside, so you can release those. 00:54:57.540 --> 00:55:03.860 align:middle line:84% So really, the process is one of resuspension, 00:55:03.860 --> 00:55:15.810 align:middle line:84% an interaction with the resuspended material, 00:55:15.810 --> 00:55:18.590 align:middle line:84% and the other one is release of pore waters. 00:55:18.590 --> 00:55:24.030 align:middle line:90% 00:55:24.030 --> 00:55:27.670 align:middle line:84% And it's not just release, it can be release and exchange. 00:55:27.670 --> 00:55:30.850 align:middle line:90% 00:55:30.850 --> 00:55:32.230 align:middle line:90% Put them all on one page. 00:55:32.230 --> 00:55:35.247 align:middle line:90% 00:55:35.247 --> 00:55:37.830 align:middle line:84% AUDIENCE: What do you guys think of pore waters in an estuary? 00:55:37.830 --> 00:55:41.358 align:middle line:90% 00:55:41.358 --> 00:55:43.890 align:middle line:84% Have you guys been to any of the little estuaries 00:55:43.890 --> 00:55:47.330 align:middle line:90% around here, the salt marshes? 00:55:47.330 --> 00:55:51.530 align:middle line:84% There's lots of what in a estuary? 00:55:51.530 --> 00:55:53.810 align:middle line:90% Lots of organic matter. 00:55:53.810 --> 00:55:55.348 align:middle line:84% So if you dig down into the mud-- 00:55:55.348 --> 00:55:57.390 align:middle line:84% it's a good field trip for you guys this weekend. 00:55:57.390 --> 00:55:59.890 align:middle line:84% Go to an estuary and dig down in the mud, 00:55:59.890 --> 00:56:02.627 align:middle line:84% you very quickly get to anoxic mud. 00:56:02.627 --> 00:56:05.210 align:middle line:84% MARGARET TIVEY: And you'll be able to tell because it'll start 00:56:05.210 --> 00:56:08.157 align:middle line:90% to smell really, really bad. 00:56:08.157 --> 00:56:10.490 align:middle line:84% AUDIENCE: And so that's one of the things in pore waters 00:56:10.490 --> 00:56:15.230 align:middle line:84% from estuaries, is you're now releasing anoxic waters, which 00:56:15.230 --> 00:56:17.930 align:middle line:84% are going to have very different metal composition. 00:56:17.930 --> 00:56:21.313 align:middle line:84% So in some ways, there is some analogy between the pH and-- 00:56:21.313 --> 00:56:22.230 align:middle line:90% MARGARET TIVEY: Right. 00:56:22.230 --> 00:56:23.605 align:middle line:84% AUDIENCE: --pH changes that we're 00:56:23.605 --> 00:56:25.150 align:middle line:90% going to talk about at the end. 00:56:25.150 --> 00:56:26.025 align:middle line:90% MARGARET TIVEY: Yeah. 00:56:26.025 --> 00:56:30.243 align:middle line:90% 00:56:30.243 --> 00:56:31.910 align:middle line:84% Yeah, and in fact, at the very end, when 00:56:31.910 --> 00:56:32.950 align:middle line:84% I'm talking about the vents, I'm going 00:56:32.950 --> 00:56:34.492 align:middle line:84% to talk about the microbial activity, 00:56:34.492 --> 00:56:37.560 align:middle line:84% but I'm not going to talk about it for the estuaries. 00:56:37.560 --> 00:56:40.830 align:middle line:84% AUDIENCE: We will talk about microbes more when you guys-- 00:56:40.830 --> 00:56:41.850 align:middle line:90% after the midterm. 00:56:41.850 --> 00:56:42.950 align:middle line:84% MARGARET TIVEY: Oh, is that right? 00:56:42.950 --> 00:56:43.450 align:middle line:90% OK. 00:56:43.450 --> 00:56:44.510 align:middle line:90% AUDIENCE: --or some bugs. 00:56:44.510 --> 00:56:46.430 align:middle line:90% MARGARET TIVEY: OK. 00:56:46.430 --> 00:56:46.930 align:middle line:90% All right. 00:56:46.930 --> 00:56:50.470 align:middle line:84% And then, speaking of bugs, this is the last one, 00:56:50.470 --> 00:56:53.830 align:middle line:90% which is you can have uptake. 00:56:53.830 --> 00:56:55.310 align:middle line:84% Did you read the notes this morning 00:56:55.310 --> 00:56:58.510 align:middle line:84% so that you could interject that properly when I needed it? 00:56:58.510 --> 00:57:00.180 align:middle line:90% Uptake by estuary-- 00:57:00.180 --> 00:57:01.930 align:middle line:84% AUDIENCE: This one's burned into my brain. 00:57:01.930 --> 00:57:04.190 align:middle line:84% I think I have this class burned into my brain. 00:57:04.190 --> 00:57:08.510 align:middle line:84% MARGARET TIVEY: You have uptake by estuary and biota. 00:57:08.510 --> 00:57:10.620 align:middle line:90% And they can remove elements. 00:57:10.620 --> 00:57:12.080 align:middle line:90% Or this can remove elements. 00:57:12.080 --> 00:57:15.940 align:middle line:84% Presumably it can also release elements, but I think 00:57:15.940 --> 00:57:17.100 align:middle line:90% it's more the-- 00:57:17.100 --> 00:57:21.997 align:middle line:84% or not uptake, but the regurgitation-- no, the-- 00:57:21.997 --> 00:57:23.580 align:middle line:84% AUDIENCE: I guess I'm kind of confused 00:57:23.580 --> 00:57:27.200 align:middle line:84% as to what the definition of conservative mixing is. 00:57:27.200 --> 00:57:28.700 align:middle line:84% MARGARET TIVEY: Oh, we'll get there. 00:57:28.700 --> 00:57:32.420 align:middle line:84% You're about you're about to see more graphs than you ever 00:57:32.420 --> 00:57:34.420 align:middle line:90% wanted to see. 00:57:34.420 --> 00:57:37.540 align:middle line:84% Basically, each of these processes 00:57:37.540 --> 00:57:40.660 align:middle line:90% either adds or removes material. 00:57:40.660 --> 00:57:43.860 align:middle line:84% If you mixed seawater and you mixed freshwater 00:57:43.860 --> 00:57:45.480 align:middle line:84% and you didn't do any of these things, 00:57:45.480 --> 00:57:49.820 align:middle line:84% then you'd see a perfect straight line like this, 00:57:49.820 --> 00:57:50.935 align:middle line:90% but we don't always. 00:57:50.935 --> 00:57:53.560 align:middle line:84% And for some elements we do, and I'm going to go through those, 00:57:53.560 --> 00:57:55.400 align:middle line:84% and for some of them we clearly don't. 00:57:55.400 --> 00:57:57.780 align:middle line:84% And so you have to explain why you're seeing 00:57:57.780 --> 00:57:59.160 align:middle line:90% the removal or the addition. 00:57:59.160 --> 00:58:02.380 align:middle line:84% And a key reason why you need to know that 00:58:02.380 --> 00:58:05.940 align:middle line:84% is because if you just take the iron value that's in rivers 00:58:05.940 --> 00:58:07.680 align:middle line:84% and say that all of that iron makes it 00:58:07.680 --> 00:58:10.585 align:middle line:84% all the way out into the ocean, you're wrong because a lot of it 00:58:10.585 --> 00:58:11.960 align:middle line:84% is left in the estuaries, and you 00:58:11.960 --> 00:58:14.600 align:middle line:84% have to try and figure out and try to quantify how much of that 00:58:14.600 --> 00:58:19.040 align:middle line:84% iron flocculates and it settles within the estuary. 00:58:19.040 --> 00:58:24.000 align:middle line:84% So right now, we're going to show you a bunch of plots-- 00:58:24.000 --> 00:58:26.680 align:middle line:84% AUDIENCE: That line, it doesn't-- 00:58:26.680 --> 00:58:29.440 align:middle line:84% I mean, that, to me, looks like you have something that's 00:58:29.440 --> 00:58:33.600 align:middle line:84% not in freshwater, and then you increase it 00:58:33.600 --> 00:58:36.880 align:middle line:90% as you go into saltwater. 00:58:36.880 --> 00:58:37.680 align:middle line:90% Whereas if it was-- 00:58:37.680 --> 00:58:39.000 align:middle line:90% MARGARET TIVEY: Right, sorry. 00:58:39.000 --> 00:58:39.500 align:middle line:90% Oh-- 00:58:39.500 --> 00:58:40.333 align:middle line:90% AUDIENCE: Well, no-- 00:58:40.333 --> 00:58:43.160 align:middle line:84% MARGARET TIVEY: I'm thinking-- you're right, this could be-- 00:58:43.160 --> 00:58:45.120 align:middle line:84% if it's high in-- you're right, most of them 00:58:45.120 --> 00:58:47.285 align:middle line:84% are higher in freshwater and drop that way. 00:58:47.285 --> 00:58:48.660 align:middle line:84% AUDIENCE: It could go either way. 00:58:48.660 --> 00:58:50.368 align:middle line:84% MARGARET TIVEY: But It can go either way. 00:58:50.368 --> 00:58:51.800 align:middle line:90% But let me just-- 00:58:51.800 --> 00:58:55.680 align:middle line:84% it's easier to look at real data. 00:58:55.680 --> 00:58:58.242 align:middle line:84% The old confusing them by trying to be simple. 00:58:58.242 --> 00:58:59.700 align:middle line:84% AUDIENCE: But if it's conservative, 00:58:59.700 --> 00:59:00.860 align:middle line:84% wouldn't it just be a horizontal? 00:59:00.860 --> 00:59:02.610 align:middle line:84% MARGARET TIVEY: Well, let's just show you. 00:59:02.610 --> 00:59:03.800 align:middle line:90% I'll show you the first one. 00:59:03.800 --> 00:59:05.950 align:middle line:84% AUDIENCE: Then the concentration would be the same in the river-- 00:59:05.950 --> 00:59:06.867 align:middle line:90% MARGARET TIVEY: Boron. 00:59:06.867 --> 00:59:09.578 align:middle line:84% OK, most of these things-- in order 00:59:09.578 --> 00:59:11.870 align:middle line:84% to look at mixing, first of all, you have to figure out 00:59:11.870 --> 00:59:13.990 align:middle line:84% what to plot it against, and you have to be plotting it 00:59:13.990 --> 00:59:15.950 align:middle line:84% against something that you're pretty confident 00:59:15.950 --> 00:59:17.430 align:middle line:90% is conservative. 00:59:17.430 --> 00:59:21.010 align:middle line:84% And in general, the salinity is relatively conservative. 00:59:21.010 --> 00:59:22.670 align:middle line:84% You are not dumping large amounts 00:59:22.670 --> 00:59:27.330 align:middle line:84% of halite or large amounts of any sea salt into estuaries. 00:59:27.330 --> 00:59:30.110 align:middle line:84% And we know that, therefore, you can say either chloride 00:59:30.110 --> 00:59:33.250 align:middle line:84% or salinity tends to be conservative. 00:59:33.250 --> 00:59:35.710 align:middle line:84% And so an element that is conservative 00:59:35.710 --> 00:59:39.510 align:middle line:84% should plot on a straight line relative to that property. 00:59:39.510 --> 00:59:41.258 align:middle line:84% AUDIENCE: [INAUDIBLE] on the axes? 00:59:41.258 --> 00:59:43.550 align:middle line:84% MARGARET TIVEY: The axes, again, this is one of these-- 00:59:43.550 --> 00:59:48.470 align:middle line:90% this is-- I believe it's micro-- 00:59:48.470 --> 00:59:49.962 align:middle line:90% it's a concentration. 00:59:49.962 --> 00:59:51.170 align:middle line:90% It doesn't matter what it is. 00:59:51.170 --> 00:59:54.590 align:middle line:90% It's a concentration. 00:59:54.590 --> 00:59:55.970 align:middle line:90% Concentration unit. 00:59:55.970 --> 00:59:57.170 align:middle line:90% And this is salinity. 00:59:57.170 --> 01:00:03.952 align:middle line:90% 01:00:03.952 --> 01:00:05.410 align:middle line:84% And if you take a look at this, you 01:00:05.410 --> 01:00:11.130 align:middle line:84% can see that within error, this boron is falling pretty much 01:00:11.130 --> 01:00:13.730 align:middle line:90% along a straight line. 01:00:13.730 --> 01:00:16.690 align:middle line:84% And so unless-- whether or not there's something actually going 01:00:16.690 --> 01:00:19.610 align:middle line:84% on here or actually going on here, 01:00:19.610 --> 01:00:21.732 align:middle line:84% you'd have to put the error bars on your analyzes 01:00:21.732 --> 01:00:23.190 align:middle line:84% and really try and figure that out, 01:00:23.190 --> 01:00:25.890 align:middle line:84% and we're going to get to issues with that in a little bit. 01:00:25.890 --> 01:00:27.530 align:middle line:84% But this is one where you clearly 01:00:27.530 --> 01:00:29.030 align:middle line:90% have conservative processes. 01:00:29.030 --> 01:00:31.530 align:middle line:84% You obviously can't be dumping a whole bunch of boron 01:00:31.530 --> 01:00:33.430 align:middle line:84% out unless you're dumping it with the salt, 01:00:33.430 --> 01:00:35.370 align:middle line:84% but we know that you're not dumping salt out. 01:00:35.370 --> 01:00:39.210 align:middle line:90% 01:00:39.210 --> 01:00:43.050 align:middle line:90% In contrast, here's iron. 01:00:43.050 --> 01:00:47.250 align:middle line:84% And again, it's simply concentration versus salinity. 01:00:47.250 --> 01:00:50.365 align:middle line:84% And so as you'll see, as [? Kristen ?] pointed out, 01:00:50.365 --> 01:00:51.490 align:middle line:90% it can be either direction. 01:00:51.490 --> 01:00:53.450 align:middle line:84% Here, there's more boron in seawater 01:00:53.450 --> 01:00:55.690 align:middle line:84% than there is in freshwater; and here, there's 01:00:55.690 --> 01:01:00.690 align:middle line:84% more iron in the rivers than there is in the saltwater. 01:01:00.690 --> 01:01:03.783 align:middle line:84% AUDIENCE: That straight line is what it would be without-- 01:01:03.783 --> 01:01:04.700 align:middle line:90% MARGARET TIVEY: Right. 01:01:04.700 --> 01:01:07.160 align:middle line:84% And the straight line is what it would be if there 01:01:07.160 --> 01:01:09.860 align:middle line:84% wasn't-- and these little dots, which are much, 01:01:09.860 --> 01:01:12.920 align:middle line:84% much smaller than the big, fat pen line, 01:01:12.920 --> 01:01:15.373 align:middle line:90% are the actual measurements. 01:01:15.373 --> 01:01:17.040 align:middle line:84% And one of the things that they've noted 01:01:17.040 --> 01:01:22.640 align:middle line:84% is, in general, iron and humic substances 01:01:22.640 --> 01:01:27.600 align:middle line:84% tend to follow this type of curve pretty well, 01:01:27.600 --> 01:01:30.840 align:middle line:84% and that's dominantly from flocculation of material 01:01:30.840 --> 01:01:36.160 align:middle line:84% and dumping in estuaries and precipitation in estuaries. 01:01:36.160 --> 01:01:38.660 align:middle line:84% That's in contrast to some other things which I'll show you, 01:01:38.660 --> 01:01:42.080 align:middle line:90% which are much more complicated. 01:01:42.080 --> 01:01:43.700 align:middle line:90% Here, you have barium. 01:01:43.700 --> 01:01:46.720 align:middle line:84% And again, all of these are real profiles. 01:01:46.720 --> 01:01:50.920 align:middle line:84% Instead of trying to show you these idealistic profiles, 01:01:50.920 --> 01:01:53.700 align:middle line:84% these have all been taken directly out of the literature, 01:01:53.700 --> 01:01:55.600 align:middle line:84% and it's real data, which is why they're not 01:01:55.600 --> 01:01:59.360 align:middle line:90% all beautiful profiles. 01:01:59.360 --> 01:02:01.310 align:middle line:84% This is for barium, and there's a fair amount 01:02:01.310 --> 01:02:05.210 align:middle line:84% of barium in both the freshwater and in the saltwater, 01:02:05.210 --> 01:02:07.270 align:middle line:84% but they're subtly different, but then you 01:02:07.270 --> 01:02:10.790 align:middle line:84% see this very, very large increase in barium, 01:02:10.790 --> 01:02:12.850 align:middle line:84% and that is likely from desorption. 01:02:12.850 --> 01:02:16.630 align:middle line:90% 01:02:16.630 --> 01:02:21.350 align:middle line:84% And then they show some really nice fun ones 01:02:21.350 --> 01:02:24.230 align:middle line:90% where you have copper. 01:02:24.230 --> 01:02:26.850 align:middle line:84% And again, this is the kind of thing where you go out, 01:02:26.850 --> 01:02:30.710 align:middle line:84% and a lot of this work was being done in the '70s, and they were 01:02:30.710 --> 01:02:32.350 align:middle line:90% really trying to figure out-- 01:02:32.350 --> 01:02:36.030 align:middle line:84% both Ed Boyle and Ed [? Shakovets ?] in our program 01:02:36.030 --> 01:02:39.670 align:middle line:84% did a lot of this work trying to make sense of the data they were 01:02:39.670 --> 01:02:41.750 align:middle line:84% collecting and trying to quantify what's going on 01:02:41.750 --> 01:02:44.550 align:middle line:84% in the estuaries so we can better quantify river 01:02:44.550 --> 01:02:46.870 align:middle line:90% fluxes into the oceans. 01:02:46.870 --> 01:02:48.710 align:middle line:84% And here, you can see that copper, 01:02:48.710 --> 01:02:51.843 align:middle line:84% it looks like it's being added at very low salinity, 01:02:51.843 --> 01:02:53.510 align:middle line:84% but then as the salinity increases some, 01:02:53.510 --> 01:02:55.130 align:middle line:84% it looks like some is being removed, 01:02:55.130 --> 01:02:56.755 align:middle line:84% and then at higher salinities, it looks 01:02:56.755 --> 01:02:59.450 align:middle line:90% like some is being added again. 01:02:59.450 --> 01:03:02.748 align:middle line:84% So copper is one that is more complicated. 01:03:02.748 --> 01:03:05.290 align:middle line:84% And you'll find that a lot of these that are more complicated 01:03:05.290 --> 01:03:07.890 align:middle line:84% are ones that have multiple different valence states, 01:03:07.890 --> 01:03:09.570 align:middle line:84% and so there's a lot of redox processes 01:03:09.570 --> 01:03:12.090 align:middle line:84% that are going on at the same time that 01:03:12.090 --> 01:03:13.430 align:middle line:90% affect what's going on. 01:03:13.430 --> 01:03:16.450 align:middle line:90% 01:03:16.450 --> 01:03:18.270 align:middle line:90% And then manganese is another. 01:03:18.270 --> 01:03:25.530 align:middle line:90% 01:03:25.530 --> 01:03:29.490 align:middle line:84% And here, you show-- there's a large removal-- 01:03:29.490 --> 01:03:32.370 align:middle line:84% in this profile, there's a large removal at low salinity 01:03:32.370 --> 01:03:34.830 align:middle line:84% and a large addition at higher salinity. 01:03:34.830 --> 01:03:42.570 align:middle line:90% 01:03:42.570 --> 01:03:44.370 align:middle line:90% AUDIENCE: On the iron plot-- 01:03:44.370 --> 01:03:44.870 align:middle line:90% sorry. 01:03:44.870 --> 01:03:46.930 align:middle line:84% MARGARET TIVEY: Is there a question up there? 01:03:46.930 --> 01:03:50.250 align:middle line:84% AUDIENCE: It might be the same one, I'm not sure. 01:03:50.250 --> 01:03:52.330 align:middle line:84% Can you just describe again why the barium 01:03:52.330 --> 01:03:53.830 align:middle line:90% has the shape that it does? 01:03:53.830 --> 01:03:55.247 align:middle line:84% MARGARET TIVEY: Oh, the barium has 01:03:55.247 --> 01:03:58.440 align:middle line:84% the shape that it does-- well, I'd have to go back to the paper 01:03:58.440 --> 01:04:00.320 align:middle line:84% to be sure why it is, but my suspicion is 01:04:00.320 --> 01:04:04.600 align:middle line:84% it's from desorption, so that you have barium 01:04:04.600 --> 01:04:07.340 align:middle line:84% on various particles that are coming into the estuaries, 01:04:07.340 --> 01:04:09.440 align:middle line:84% and then when it mixes with the salt, 01:04:09.440 --> 01:04:12.020 align:middle line:84% the barium is being-- there's exchange going on, 01:04:12.020 --> 01:04:14.200 align:middle line:84% and some other ion is replacing the barium 01:04:14.200 --> 01:04:17.970 align:middle line:84% and the barium is being released. 01:04:17.970 --> 01:04:21.123 align:middle line:84% Sort of like calcium and sodium exchange. 01:04:21.123 --> 01:04:23.040 align:middle line:84% AUDIENCE: Could you explain what was happening 01:04:23.040 --> 01:04:24.920 align:middle line:90% in iron profile [INAUDIBLE] 01:04:24.920 --> 01:04:26.600 align:middle line:84% MARGARET TIVEY: In the iron profile-- 01:04:26.600 --> 01:04:28.000 align:middle line:90% oh. 01:04:28.000 --> 01:04:31.640 align:middle line:84% AUDIENCE: On these plots, are you seeing just the free ion 01:04:31.640 --> 01:04:36.120 align:middle line:84% concentration or are you seeing also that in solution, but bound 01:04:36.120 --> 01:04:38.688 align:middle line:90% to some particle? 01:04:38.688 --> 01:04:40.480 align:middle line:84% MARGARET TIVEY: What you are measuring here 01:04:40.480 --> 01:04:42.272 align:middle line:84% when you do this-- and we'll get to it when 01:04:42.272 --> 01:04:44.960 align:middle line:84% we do the in-laboratory ones, is you're taking the fluid 01:04:44.960 --> 01:04:48.280 align:middle line:84% and you're taking the filtered portion, the less than 0.45 01:04:48.280 --> 01:04:50.120 align:middle line:84% micron portion of the fluid, you're 01:04:50.120 --> 01:04:53.360 align:middle line:84% analyzing that and coming up with the total iron. 01:04:53.360 --> 01:04:58.580 align:middle line:84% So this is looking at total iron in the 0.45-micron-and-less 01:04:58.580 --> 01:05:01.140 align:middle line:90% fraction, I believe. 01:05:01.140 --> 01:05:02.675 align:middle line:84% Yeah, that's what they usually do. 01:05:02.675 --> 01:05:04.300 align:middle line:84% You'd have to read each paper carefully 01:05:04.300 --> 01:05:05.925 align:middle line:84% to find out exactly what they're doing, 01:05:05.925 --> 01:05:08.100 align:middle line:84% but in general, that's what they do. 01:05:08.100 --> 01:05:10.980 align:middle line:84% So no, you're not looking at the ion that's on the large 01:05:10.980 --> 01:05:14.880 align:middle line:84% particles that are left on the 0.45-micron filter paper, 01:05:14.880 --> 01:05:18.580 align:middle line:84% but anything that can pass through that filter is included 01:05:18.580 --> 01:05:19.460 align:middle line:90% in this. 01:05:19.460 --> 01:05:22.880 align:middle line:84% AUDIENCE: So that would be truly dissolved free ions. 01:05:22.880 --> 01:05:24.880 align:middle line:84% It would be things that are complex in solution. 01:05:24.880 --> 01:05:25.797 align:middle line:90% MARGARET TIVEY: Right. 01:05:25.797 --> 01:05:26.502 align:middle line:90% So it includes-- 01:05:26.502 --> 01:05:27.460 align:middle line:90% AUDIENCE: And colloids. 01:05:27.460 --> 01:05:28.377 align:middle line:90% MARGARET TIVEY: Right. 01:05:28.377 --> 01:05:30.980 align:middle line:90% 01:05:30.980 --> 01:05:39.820 align:middle line:84% So if we go back to this figure where 01:05:39.820 --> 01:05:42.700 align:middle line:84% we were looking at what was in the river water, 01:05:42.700 --> 01:05:46.300 align:middle line:84% once you get down below this 0.45 micron, 01:05:46.300 --> 01:05:48.600 align:middle line:84% it would include some of these clays as well. 01:05:48.600 --> 01:05:52.050 align:middle line:90% 01:05:52.050 --> 01:05:54.050 align:middle line:84% [? Katelyn, ?] did you have another question? 01:05:54.050 --> 01:05:55.930 align:middle line:84% AUDIENCE: Well, I was just wondering, 01:05:55.930 --> 01:05:57.930 align:middle line:84% it looks like in the iron profile, 01:05:57.930 --> 01:05:59.838 align:middle line:84% that it dips below the conservative-- 01:05:59.838 --> 01:06:00.630 align:middle line:90% MARGARET TIVEY: OK. 01:06:00.630 --> 01:06:01.470 align:middle line:90% AUDIENCE: --and rejoins it. 01:06:01.470 --> 01:06:01.890 align:middle line:90% MARGARET TIVEY: Perfect. 01:06:01.890 --> 01:06:02.910 align:middle line:90% Perfect question. 01:06:02.910 --> 01:06:03.530 align:middle line:90% OK. 01:06:03.530 --> 01:06:07.970 align:middle line:84% Now one of the things is, is it one simple process going on? 01:06:07.970 --> 01:06:10.790 align:middle line:84% And these are all assuming that you only have two endmembers. 01:06:10.790 --> 01:06:14.052 align:middle line:84% You either you have a seawater endmember 01:06:14.052 --> 01:06:15.510 align:middle line:84% and you have a freshwater endmember 01:06:15.510 --> 01:06:17.110 align:middle line:84% and you don't have any other endmembers. 01:06:17.110 --> 01:06:18.902 align:middle line:84% And they're trying to simplify these things 01:06:18.902 --> 01:06:22.490 align:middle line:84% and come up with fairly straightforward processes 01:06:22.490 --> 01:06:24.350 align:middle line:84% that they can extrapolate globally 01:06:24.350 --> 01:06:28.570 align:middle line:84% so they can come up with a good idea of what global fluxes are. 01:06:28.570 --> 01:06:32.150 align:middle line:84% However, because of the type of thing you just talked about, 01:06:32.150 --> 01:06:34.810 align:middle line:84% [? Katelyn, ?] there's also concern about whether 01:06:34.810 --> 01:06:36.890 align:middle line:84% or not there might be a third component. 01:06:36.890 --> 01:06:39.530 align:middle line:90% And so there are some examples-- 01:06:39.530 --> 01:06:41.150 align:middle line:90% and this shows one here. 01:06:41.150 --> 01:06:42.950 align:middle line:90% This was work done by Ed Boyle. 01:06:42.950 --> 01:06:45.090 align:middle line:84% He went and looked back at-- this 01:06:45.090 --> 01:06:48.250 align:middle line:90% is a dissolved silica profile. 01:06:48.250 --> 01:06:52.410 align:middle line:84% And what could be-- it could be interpreted-- 01:06:52.410 --> 01:06:56.430 align:middle line:84% a lot of people would just interpret that as simple-- 01:06:56.430 --> 01:07:00.250 align:middle line:84% from either colloids or desorption-- no, 01:07:00.250 --> 01:07:02.610 align:middle line:84% not desorption, adsorption or something else. 01:07:02.610 --> 01:07:05.750 align:middle line:84% But what he attributed it to instead 01:07:05.750 --> 01:07:11.030 align:middle line:84% was a third component, a third mixing-- 01:07:11.030 --> 01:07:13.830 align:middle line:90% I mean a third endmember. 01:07:13.830 --> 01:07:15.310 align:middle line:84% And the reason for that is silica 01:07:15.310 --> 01:07:19.590 align:middle line:84% tends to be conservative when you mix, and it was very-- 01:07:19.590 --> 01:07:24.110 align:middle line:84% it was somewhat confusing why you would see this decrease-- 01:07:24.110 --> 01:07:26.090 align:middle line:84% because what would be the removal mechanism, 01:07:26.090 --> 01:07:27.770 align:middle line:90% nobody had a removal mechanism. 01:07:27.770 --> 01:07:29.390 align:middle line:84% So his hypothesis is that there's 01:07:29.390 --> 01:07:35.030 align:middle line:84% a third source here of fluid that has a lower silica 01:07:35.030 --> 01:07:36.630 align:middle line:84% composition, and that you actually 01:07:36.630 --> 01:07:43.630 align:middle line:84% have conservative mixing between this source and the seawater 01:07:43.630 --> 01:07:47.670 align:middle line:84% source and between this source and the river source. 01:07:47.670 --> 01:07:50.980 align:middle line:84% AUDIENCE: Can you point out what in the iron 01:07:50.980 --> 01:07:52.160 align:middle line:90% that you're talking about? 01:07:52.160 --> 01:07:53.320 align:middle line:84% MARGARET TIVEY: Oh, we're going to get there. 01:07:53.320 --> 01:07:55.040 align:middle line:84% We're going to get to that's messy data. 01:07:55.040 --> 01:07:58.220 align:middle line:84% Again, none of these have error bars on them. 01:07:58.220 --> 01:08:02.580 align:middle line:84% You also-- all you have to do is have one aggregate get 01:08:02.580 --> 01:08:08.140 align:middle line:84% into your bottle or have one colloid stick to the side 01:08:08.140 --> 01:08:09.040 align:middle line:90% of your container-- 01:08:09.040 --> 01:08:10.415 align:middle line:84% I mean, there's a lot-- there are 01:08:10.415 --> 01:08:12.860 align:middle line:84% a lot of things that can create noise in these data sets. 01:08:12.860 --> 01:08:17.479 align:middle line:90% 01:08:17.479 --> 01:08:18.979 align:middle line:84% But the key thing of this is for you 01:08:18.979 --> 01:08:21.700 align:middle line:84% to understand how to look at a profile 01:08:21.700 --> 01:08:24.040 align:middle line:84% and determine whether there's been removal or addition, 01:08:24.040 --> 01:08:27.140 align:middle line:84% and to have some idea of what is likely causing 01:08:27.140 --> 01:08:28.920 align:middle line:90% that removal or the addition. 01:08:28.920 --> 01:08:32.939 align:middle line:90% And again, here, what confused-- 01:08:32.939 --> 01:08:36.240 align:middle line:84% the reason Ed Boyle went back to look at this was in general, 01:08:36.240 --> 01:08:39.340 align:middle line:84% he was finding another profiles that silica was conservative, 01:08:39.340 --> 01:08:43.420 align:middle line:84% so an alternative interpretation of this 01:08:43.420 --> 01:08:47.198 align:middle line:84% is that you have a third source fluid source. 01:08:47.198 --> 01:08:49.240 align:middle line:84% AUDIENCE: So an example of that would be like two 01:08:49.240 --> 01:08:50.623 align:middle line:90% different ocean currents-- 01:08:50.623 --> 01:08:51.540 align:middle line:90% MARGARET TIVEY: Well-- 01:08:51.540 --> 01:08:53.075 align:middle line:90% AUDIENCE: --mixing with a river? 01:08:53.075 --> 01:08:54.200 align:middle line:90% MARGARET TIVEY: Or having-- 01:08:54.200 --> 01:08:56.080 align:middle line:84% AUDIENCE: --rivers and the coastal water or something 01:08:56.080 --> 01:08:56.840 align:middle line:90% like that? 01:08:56.840 --> 01:08:56.990 align:middle line:90% MARGARET TIVEY: Right. 01:08:56.990 --> 01:08:59.282 align:middle line:84% Either two rivers and a coastal water, or in this case, 01:08:59.282 --> 01:09:01.887 align:middle line:90% it was actually a shelf source. 01:09:01.887 --> 01:09:03.720 align:middle line:84% And we're going to get into groundwater flow 01:09:03.720 --> 01:09:06.540 align:middle line:84% as well, you can end up with groundwater flow source. 01:09:06.540 --> 01:09:07.040 align:middle line:90% OK. 01:09:07.040 --> 01:09:13.120 align:middle line:90% 01:09:13.120 --> 01:09:13.620 align:middle line:90% Yes. 01:09:13.620 --> 01:09:16.020 align:middle line:84% He ended up with a-- for this one in particular, 01:09:16.020 --> 01:09:18.399 align:middle line:84% he had a river source, an open ocean source, and then 01:09:18.399 --> 01:09:20.439 align:middle line:90% an intermediate shelf source. 01:09:20.439 --> 01:09:24.295 align:middle line:84% I'm not sure what the source of the shelf source was, 01:09:24.295 --> 01:09:25.420 align:middle line:90% but it didn't go into that. 01:09:25.420 --> 01:09:26.840 align:middle line:84% But there was basically, you could 01:09:26.840 --> 01:09:30.123 align:middle line:84% go out-- so you then go out and sample that body of water, 01:09:30.123 --> 01:09:32.040 align:middle line:84% do some CTD casts, and see if you can actually 01:09:32.040 --> 01:09:33.700 align:middle line:90% find that fluid out there. 01:09:33.700 --> 01:09:38.279 align:middle line:90% 01:09:38.279 --> 01:09:40.560 align:middle line:90% All right. 01:09:40.560 --> 01:09:42.840 align:middle line:84% Now, because of these complexities 01:09:42.840 --> 01:09:48.870 align:middle line:84% and some of the questions that [? Katelyn ?] was raising, 01:09:48.870 --> 01:09:50.950 align:middle line:84% you do have a concern and a problem 01:09:50.950 --> 01:09:53.790 align:middle line:90% when you have messy data. 01:09:53.790 --> 01:09:55.330 align:middle line:84% I talked about some of the issues. 01:09:55.330 --> 01:10:01.110 align:middle line:84% And here is a profile that shows copper and a mixing line. 01:10:01.110 --> 01:10:03.910 align:middle line:84% And the real question is, is this actually 01:10:03.910 --> 01:10:08.430 align:middle line:84% conservative mixing or do you have some addition going on here 01:10:08.430 --> 01:10:10.370 align:middle line:84% and a little bit of addition going on there? 01:10:10.370 --> 01:10:13.550 align:middle line:84% What's really going on, and the data are very, very noisy. 01:10:13.550 --> 01:10:17.470 align:middle line:84% So Ed [? Shakovets ?] was one of the key people 01:10:17.470 --> 01:10:18.930 align:middle line:90% who helped develop this. 01:10:18.930 --> 01:10:21.530 align:middle line:84% You can also do your own mixing diagrams. 01:10:21.530 --> 01:10:22.610 align:middle line:90% This is all field data. 01:10:22.610 --> 01:10:24.190 align:middle line:90% So you can just take-- 01:10:24.190 --> 01:10:26.410 align:middle line:84% one option is to go out to the open ocean-- 01:10:26.410 --> 01:10:30.260 align:middle line:84% so go to this station, collect a bunch of this water, 01:10:30.260 --> 01:10:32.510 align:middle line:84% go to the river source, collect a bunch of that water, 01:10:32.510 --> 01:10:35.847 align:middle line:84% the fresh source, and then do the mixing in the lab after 01:10:35.847 --> 01:10:38.430 align:middle line:84% you've-- and you can either do this mixing depending on if you 01:10:38.430 --> 01:10:43.170 align:middle line:84% want to look at particle processes or colloid processes, 01:10:43.170 --> 01:10:46.530 align:middle line:84% you either filter or do it unfiltered. 01:10:46.530 --> 01:10:50.370 align:middle line:84% This is an example of an unfiltered river water. 01:10:50.370 --> 01:10:56.650 align:middle line:84% It says unfiltered river water's 0.4-micron filters, 01:10:56.650 --> 01:10:59.870 align:middle line:84% which implies that it's filtered seawater, but anyway, 01:10:59.870 --> 01:11:02.530 align:middle line:90% you have to know what-- 01:11:02.530 --> 01:11:04.690 align:middle line:84% you would report in the paper exactly what you 01:11:04.690 --> 01:11:06.330 align:middle line:90% did with those fluids. 01:11:06.330 --> 01:11:12.210 align:middle line:84% But when they did that mixing experiment, 01:11:12.210 --> 01:11:14.710 align:middle line:84% this was the data they got from the mixing experiment, 01:11:14.710 --> 01:11:15.370 align:middle line:90% and it really-- 01:11:15.370 --> 01:11:18.210 align:middle line:84% AUDIENCE: I'm so confused as to the definition of conservative 01:11:18.210 --> 01:11:20.610 align:middle line:84% mixing versus non-conservative mixing because-- 01:11:20.610 --> 01:11:24.650 align:middle line:84% I mean, is it lab mixing or is it field mixing? 01:11:24.650 --> 01:11:27.770 align:middle line:84% Because some of the processes that we went over 01:11:27.770 --> 01:11:30.250 align:middle line:90% wouldn't happen in a lab. 01:11:30.250 --> 01:11:31.730 align:middle line:84% They're not happening in the lab, 01:11:31.730 --> 01:11:35.690 align:middle line:84% but they're happening in the field, what you call it, and-- 01:11:35.690 --> 01:11:38.210 align:middle line:84% MARGARET TIVEY: You call it non-conservative 01:11:38.210 --> 01:11:39.870 align:middle line:84% mixing no matter what's going on, 01:11:39.870 --> 01:11:42.260 align:middle line:84% but you have to identify the process that's going on. 01:11:42.260 --> 01:11:44.520 align:middle line:84% So you're right, this type of mixing experiment 01:11:44.520 --> 01:11:47.400 align:middle line:84% is only going to look at desorption-- chemical 01:11:47.400 --> 01:11:49.345 align:middle line:84% processes between those two bodies of water. 01:11:49.345 --> 01:11:51.720 align:middle line:84% It's not going to be considering any of this resuspension 01:11:51.720 --> 01:11:52.327 align:middle line:90% of sediment. 01:11:52.327 --> 01:11:53.160 align:middle line:90% AUDIENCE: Or biota-- 01:11:53.160 --> 01:11:56.160 align:middle line:84% MARGARET TIVEY: Or biota, right, unless there's-- 01:11:56.160 --> 01:11:57.760 align:middle line:84% well, except for microbial activity 01:11:57.760 --> 01:12:00.040 align:middle line:84% that's actually taking place in the water column-- 01:12:00.040 --> 01:12:02.640 align:middle line:84% in the two fluid samples that you've taken, 01:12:02.640 --> 01:12:04.800 align:middle line:84% but it's certainly not going to-- 01:12:04.800 --> 01:12:07.200 align:middle line:84% but for this, this is what they were looking at. 01:12:07.200 --> 01:12:10.372 align:middle line:84% They were trying to figure out, is copper being desorbed? 01:12:10.372 --> 01:12:12.080 align:middle line:84% Is there additional or is there a removal 01:12:12.080 --> 01:12:13.500 align:middle line:90% or is it being adsorbed? 01:12:13.500 --> 01:12:16.565 align:middle line:90% 01:12:16.565 --> 01:12:19.600 align:middle line:90% And then this was-- 01:12:19.600 --> 01:12:22.960 align:middle line:84% some other examples are in your notes. 01:12:22.960 --> 01:12:24.113 align:middle line:90% This is a much messier one. 01:12:24.113 --> 01:12:25.780 align:middle line:84% Take a look at that nice nickel profile. 01:12:25.780 --> 01:12:27.440 align:middle line:84% And I'm sure that scatter in large part 01:12:27.440 --> 01:12:33.538 align:middle line:84% has to do with errors on the analyzes. 01:12:33.538 --> 01:12:35.080 align:middle line:84% And then when they did it in the lab, 01:12:35.080 --> 01:12:37.620 align:middle line:84% they got a much cleaner data set. 01:12:37.620 --> 01:12:41.910 align:middle line:90% 01:12:41.910 --> 01:12:44.730 align:middle line:84% And similarly-- and then for calcium-- 01:12:44.730 --> 01:12:50.770 align:middle line:84% I mean for cadmium, the data were, again, ambiguous. 01:12:50.770 --> 01:12:56.510 align:middle line:84% For instance, is there actually a third source sitting here 01:12:56.510 --> 01:12:59.010 align:middle line:90% or is this simple desorption? 01:12:59.010 --> 01:13:01.030 align:middle line:84% And when they did the mixing calculation-- 01:13:01.030 --> 01:13:03.430 align:middle line:84% or the mixing experiments in the lab, 01:13:03.430 --> 01:13:06.450 align:middle line:84% they saw that you get this non-uniform-- 01:13:06.450 --> 01:13:09.470 align:middle line:84% you get more desorption occurring at low salinity 01:13:09.470 --> 01:13:12.150 align:middle line:84% than at high salinity, but the entire profile 01:13:12.150 --> 01:13:13.750 align:middle line:90% can be explained by desorption. 01:13:13.750 --> 01:13:17.375 align:middle line:90% 01:13:17.375 --> 01:13:18.750 align:middle line:84% And again, all of these details-- 01:13:18.750 --> 01:13:21.110 align:middle line:84% I mean, there isn't-- you cannot just look at a data set 01:13:21.110 --> 01:13:23.490 align:middle line:84% and identify exactly what's going on. 01:13:23.490 --> 01:13:27.330 align:middle line:84% It's simply an interpretation of field data. 01:13:27.330 --> 01:13:30.283 align:middle line:84% And as shown by Ed Boyle, going back and reinterpreting one, 01:13:30.283 --> 01:13:32.950 align:middle line:84% the interpretations that are out there for all of these profiles 01:13:32.950 --> 01:13:36.810 align:middle line:90% are not necessarily 100% true. 01:13:36.810 --> 01:13:42.170 align:middle line:84% I mean, this is their hypothesis as to what's going on right now. 01:13:42.170 --> 01:13:46.310 align:middle line:84% Now there's a-- again in your notes, there's a generalization. 01:13:46.310 --> 01:13:52.470 align:middle line:84% This table gives you an idea of, in general, 01:13:52.470 --> 01:13:53.930 align:middle line:90% what happens with various ions. 01:13:53.930 --> 01:13:56.530 align:middle line:90% And in general, silica-- 01:13:56.530 --> 01:13:58.330 align:middle line:90% can you actually see that? 01:13:58.330 --> 01:13:59.150 align:middle line:90% Probably not. 01:13:59.150 --> 01:14:01.890 align:middle line:90% 01:14:01.890 --> 01:14:07.690 align:middle line:84% But silica, uranium, nickel, selenium, arsenic, a lot 01:14:07.690 --> 01:14:10.570 align:middle line:84% of these things in most rivers and estuaries 01:14:10.570 --> 01:14:14.270 align:middle line:84% are conservative except for manganese. 01:14:14.270 --> 01:14:17.510 align:middle line:90% Actually, it can differ. 01:14:17.510 --> 01:14:18.417 align:middle line:90% It can be any. 01:14:18.417 --> 01:14:20.250 align:middle line:84% So this basically talks about whether or not 01:14:20.250 --> 01:14:25.250 align:middle line:84% there's input, namely addition, whether there's removal, 01:14:25.250 --> 01:14:27.430 align:middle line:84% or whether there tends to be conservative mixing, 01:14:27.430 --> 01:14:28.270 align:middle line:90% and it generalizes. 01:14:28.270 --> 01:14:30.210 align:middle line:84% And you'll see that copper, manganese, 01:14:30.210 --> 01:14:33.810 align:middle line:84% and a couple of other elements can have any one of the three 01:14:33.810 --> 01:14:38.240 align:middle line:84% going on depending on what estuary they're in. 01:14:38.240 --> 01:14:40.720 align:middle line:90% OK. 01:14:40.720 --> 01:14:46.960 align:middle line:84% AUDIENCE: What's the sign for the universal behavior that 01:14:46.960 --> 01:14:48.380 align:middle line:90% got cut off at the bottom? 01:14:48.380 --> 01:14:53.000 align:middle line:84% Is that underlined or is it a circle around the crop? 01:14:53.000 --> 01:14:55.580 align:middle line:84% MARGARET TIVEY: I believe it's the underlined-- right, 01:14:55.580 --> 01:14:58.040 align:middle line:90% that's-- sorry. 01:14:58.040 --> 01:15:01.240 align:middle line:90% That's universal behavior. 01:15:01.240 --> 01:15:04.580 align:middle line:84% And so you'll see that barium is almost always-- 01:15:04.580 --> 01:15:09.200 align:middle line:84% so barium, radium, cadmium are almost always added, 01:15:09.200 --> 01:15:13.860 align:middle line:84% whereas iron and beryllium and aluminum are almost-- 01:15:13.860 --> 01:15:16.380 align:middle line:84% and rare earth elements are almost always removed. 01:15:16.380 --> 01:15:17.440 align:middle line:90% AUDIENCE: And humics. 01:15:17.440 --> 01:15:18.280 align:middle line:90% MARGARET TIVEY: And humics. 01:15:18.280 --> 01:15:19.580 align:middle line:84% AUDIENCE: Is that what the AG is? 01:15:19.580 --> 01:15:20.913 align:middle line:90% MARGARET TIVEY: The humic acids. 01:15:20.913 --> 01:15:27.080 align:middle line:90% 01:15:27.080 --> 01:15:28.580 align:middle line:90% OK. 01:15:28.580 --> 01:15:31.814 align:middle line:90% 01:15:31.814 --> 01:15:34.620 align:middle line:84% But you'll notice that it's not very many of these that 01:15:34.620 --> 01:15:37.900 align:middle line:90% have this universal behavior. 01:15:37.900 --> 01:15:42.460 align:middle line:84% I'm surprised silica is removed sometimes. 01:15:42.460 --> 01:15:45.768 align:middle line:90% OK. 01:15:45.768 --> 01:15:48.440 align:middle line:84% You can also have some other interesting things happen. 01:15:48.440 --> 01:15:52.600 align:middle line:84% There's an example of uranium, a nice, nasty one. 01:15:52.600 --> 01:15:58.340 align:middle line:84% And this-- I'm sorry, this plot is truly hideous. 01:15:58.340 --> 01:16:02.800 align:middle line:84% It's best to read the notes and read the figure caption, 01:16:02.800 --> 01:16:05.720 align:middle line:84% but all this is really showing is that in some places, 01:16:05.720 --> 01:16:07.760 align:middle line:84% you tend to have conservative mixing of uranium; 01:16:07.760 --> 01:16:12.200 align:middle line:84% in others, you have a removal of uranium; 01:16:12.200 --> 01:16:13.720 align:middle line:84% and in others, you have addition. 01:16:13.720 --> 01:16:17.400 align:middle line:84% And supposedly, on this diagram, you see addition of uranium, 01:16:17.400 --> 01:16:19.540 align:middle line:90% but I can't see it myself. 01:16:19.540 --> 01:16:24.460 align:middle line:84% And one of the hypotheses for what's going on 01:16:24.460 --> 01:16:26.420 align:middle line:84% is that the uranium is bound in the iron 01:16:26.420 --> 01:16:29.600 align:middle line:84% oxyhydroxides, these colloids-- and this is in your notes. 01:16:29.600 --> 01:16:33.170 align:middle line:84% These colloids flocculate, they settle on the bottom. 01:16:33.170 --> 01:16:36.550 align:middle line:84% Then these iron oxyhydroxide coatings dissolve, 01:16:36.550 --> 01:16:39.310 align:middle line:84% releasing the uranium back up into the water column, 01:16:39.310 --> 01:16:41.210 align:middle line:84% so with time, you end up with an addition 01:16:41.210 --> 01:16:42.790 align:middle line:90% of uranium in the estuary. 01:16:42.790 --> 01:16:45.490 align:middle line:84% AUDIENCE: Well, the iron oxyhydroxides dissolve 01:16:45.490 --> 01:16:47.250 align:middle line:90% in anoxic sediments, right? 01:16:47.250 --> 01:16:49.770 align:middle line:90% Is that the key step? 01:16:49.770 --> 01:16:52.130 align:middle line:84% MARGARET TIVEY: I would think because-- 01:16:52.130 --> 01:16:53.870 align:middle line:84% except you can also have exchange. 01:16:53.870 --> 01:16:56.570 align:middle line:90% I mean, uranium is-- 01:16:56.570 --> 01:16:58.550 align:middle line:84% we don't need to go into all the details. 01:16:58.550 --> 01:17:00.325 align:middle line:84% The point is, as I said before, I 01:17:00.325 --> 01:17:02.450 align:middle line:84% don't want you to memorize exactly what's happening 01:17:02.450 --> 01:17:03.270 align:middle line:90% to every element. 01:17:03.270 --> 01:17:05.550 align:middle line:84% I want you to understand the processes that can go on. 01:17:05.550 --> 01:17:07.770 align:middle line:84% And another additional-- another process 01:17:07.770 --> 01:17:11.810 align:middle line:84% that can lead to addition is interaction-- 01:17:11.810 --> 01:17:14.090 align:middle line:84% is dissolution of material that has 01:17:14.090 --> 01:17:18.330 align:middle line:84% settled on the bottom as the conditions change. 01:17:18.330 --> 01:17:22.490 align:middle line:84% And if there's any dissolution or any ion exchange going on, 01:17:22.490 --> 01:17:23.870 align:middle line:90% things can get desorbed later. 01:17:23.870 --> 01:17:28.650 align:middle line:84% Things that take a longer time than they take-- so you just 01:17:28.650 --> 01:17:31.350 align:middle line:84% have to think, think about what processes could possibly 01:17:31.350 --> 01:17:32.090 align:middle line:90% be going on. 01:17:32.090 --> 01:17:35.260 align:middle line:90% 01:17:35.260 --> 01:17:37.790 align:middle line:84% OK, now we're going to get into radium isotopes, which 01:17:37.790 --> 01:17:41.150 align:middle line:84% is going to segue us into groundwater, 01:17:41.150 --> 01:17:46.190 align:middle line:84% but in general, radium isotopes can 01:17:46.190 --> 01:17:49.990 align:middle line:84% help unravel some of these very complex processes that 01:17:49.990 --> 01:17:52.307 align:middle line:90% are going on. 01:17:52.307 --> 01:17:53.390 align:middle line:90% I have to make sure that-- 01:17:53.390 --> 01:17:58.110 align:middle line:84% I have to speed up, otherwise I won't get to my favorite part. 01:17:58.110 --> 01:18:00.570 align:middle line:84% The vents will get shafted again. 01:18:00.570 --> 01:18:01.140 align:middle line:90% OK. 01:18:01.140 --> 01:18:06.022 align:middle line:84% So radium isotopes, Bill talked about radium isotopes. 01:18:06.022 --> 01:18:07.730 align:middle line:84% I'm not going to go into all the details, 01:18:07.730 --> 01:18:10.022 align:middle line:84% but you know that there are multiple different isotopes 01:18:10.022 --> 01:18:10.790 align:middle line:90% of radium. 01:18:10.790 --> 01:18:15.070 align:middle line:84% Radium behaves similarly to calcium and barium. 01:18:15.070 --> 01:18:29.140 align:middle line:84% And you can have radium adsorbed on exchange sites, 01:18:29.140 --> 01:18:31.362 align:middle line:90% such as negatively charged-- 01:18:31.362 --> 01:18:32.820 align:middle line:84% on the exchange sites of negatively 01:18:32.820 --> 01:18:37.040 align:middle line:84% charged clay particles in river water. 01:18:37.040 --> 01:18:41.740 align:middle line:90% 01:18:41.740 --> 01:18:55.800 align:middle line:84% And then it is rapidly desorbed in estuaries by ion exchange. 01:18:55.800 --> 01:18:59.260 align:middle line:90% 01:18:59.260 --> 01:19:02.400 align:middle line:84% The ion exchange occurs as salinity increases. 01:19:02.400 --> 01:19:05.180 align:middle line:90% 01:19:05.180 --> 01:19:08.580 align:middle line:84% However, if the radium was only occurring 01:19:08.580 --> 01:19:10.620 align:middle line:84% because of this mixing, you would expect 01:19:10.620 --> 01:19:14.500 align:middle line:90% to see the exact same ratios. 01:19:14.500 --> 01:19:19.740 align:middle line:84% So you'd expect-- if you see the isotope ratios, 01:19:19.740 --> 01:19:21.260 align:middle line:84% you ask yourself the question, are 01:19:21.260 --> 01:19:30.260 align:middle line:84% isotope ratios the same on the particles, 01:19:30.260 --> 01:19:36.340 align:middle line:84% on the river particles, as they are in the estuary water? 01:19:36.340 --> 01:19:42.600 align:middle line:90% 01:19:42.600 --> 01:19:44.060 align:middle line:90% And the answer is no. 01:19:44.060 --> 01:19:49.524 align:middle line:90% 01:19:49.524 --> 01:19:53.800 align:middle line:84% Basically, there's a lot more radium-224 than-- 01:19:53.800 --> 01:19:57.780 align:middle line:84% the radium-224 is too high in the estuary. 01:19:57.780 --> 01:20:01.000 align:middle line:90% 01:20:01.000 --> 01:20:02.800 align:middle line:84% And when they looked at that, they then 01:20:02.800 --> 01:20:05.140 align:middle line:84% took a look at what other processes might be happening, 01:20:05.140 --> 01:20:09.560 align:middle line:84% and that was when they account for this excess radium-224 01:20:09.560 --> 01:20:12.260 align:middle line:90% by resuspension of sediments. 01:20:12.260 --> 01:20:16.280 align:middle line:90% 01:20:16.280 --> 01:20:18.440 align:middle line:84% And that results in extra release 01:20:18.440 --> 01:20:21.200 align:middle line:84% of radium-224, which can grow into the sediments 01:20:21.200 --> 01:20:22.920 align:middle line:84% because it grows in rapidly, whereas 01:20:22.920 --> 01:20:28.390 align:middle line:84% radium-226 and radium-228 take a lot longer to grow in. 01:20:28.390 --> 01:20:45.590 align:middle line:84% So 224-radium grows into said particles more rapidly. 01:20:45.590 --> 01:20:49.790 align:middle line:84% And that allows you to use radium isotopes 01:20:49.790 --> 01:20:52.450 align:middle line:90% as tracers of processes. 01:20:52.450 --> 01:20:55.575 align:middle line:90% 01:20:55.575 --> 01:20:57.450 align:middle line:84% And there are a couple graphs in your notes-- 01:20:57.450 --> 01:21:00.033 align:middle line:84% I'm not going to go through them because you can look at them, 01:21:00.033 --> 01:21:04.310 align:middle line:84% but they show excesses, they show addition of radium. 01:21:04.310 --> 01:21:06.930 align:middle line:84% And when you do these calculations-- well, 01:21:06.930 --> 01:21:09.710 align:middle line:90% I'll just show you one. 01:21:09.710 --> 01:21:14.690 align:middle line:84% Take a look at the radium-224, 226, and 228, 01:21:14.690 --> 01:21:17.510 align:middle line:84% and you see that there's much greater in growth of-- 01:21:17.510 --> 01:21:24.090 align:middle line:84% I mean, much greater abundances in addition of radium-224. 01:21:24.090 --> 01:21:24.957 align:middle line:90% Wonderful figures. 01:21:24.957 --> 01:21:26.790 align:middle line:84% AUDIENCE: I just-- you can't see the symbol, 01:21:26.790 --> 01:21:28.350 align:middle line:84% so you don't really know which one's which. 01:21:28.350 --> 01:21:29.830 align:middle line:84% MARGARET TIVEY: Well, you can in your notes. 01:21:29.830 --> 01:21:30.420 align:middle line:90% AUDIENCE: You can? 01:21:30.420 --> 01:21:30.530 align:middle line:90% OK. 01:21:30.530 --> 01:21:31.190 align:middle line:90% MARGARET TIVEY: Yeah. 01:21:31.190 --> 01:21:32.690 align:middle line:84% One of the things we're trying to do 01:21:32.690 --> 01:21:34.173 align:middle line:84% is figure out the time to redraft 01:21:34.173 --> 01:21:35.590 align:middle line:84% every single one of these figures, 01:21:35.590 --> 01:21:38.770 align:middle line:84% but we also have to go back and find exactly what paper they all 01:21:38.770 --> 01:21:41.130 align:middle line:90% came out of. 01:21:41.130 --> 01:21:43.930 align:middle line:90% OK. 01:21:43.930 --> 01:21:44.677 align:middle line:90% All right. 01:21:44.677 --> 01:21:46.510 align:middle line:84% AUDIENCE: How not to obey the copyright law. 01:21:46.510 --> 01:21:47.710 align:middle line:90% MARGARET TIVEY: Exactly. 01:21:47.710 --> 01:21:48.930 align:middle line:90% That's the next problem. 01:21:48.930 --> 01:21:49.440 align:middle line:90% OK. 01:21:49.440 --> 01:21:52.092 align:middle line:84% So-- well, for-- it's fine as long as you're lecturing. 01:21:52.092 --> 01:21:54.550 align:middle line:84% AUDIENCE: No, I mean these, since we don't have the paper-- 01:21:54.550 --> 01:21:54.960 align:middle line:90% MARGARET TIVEY: Right. 01:21:54.960 --> 01:21:56.090 align:middle line:90% That's right, yeah. 01:21:56.090 --> 01:21:57.530 align:middle line:90% OK. 01:21:57.530 --> 01:21:58.210 align:middle line:90% All right. 01:21:58.210 --> 01:22:00.770 align:middle line:90% So, groundwater. 01:22:00.770 --> 01:22:01.690 align:middle line:90% AUDIENCE: Question. 01:22:01.690 --> 01:22:04.313 align:middle line:90% MARGARET TIVEY: Yeah. 01:22:04.313 --> 01:22:06.730 align:middle line:84% AUDIENCE: I'm a little confused by this term that you said 01:22:06.730 --> 01:22:09.745 align:middle line:84% growth in, that radium-224 has a-- 01:22:09.745 --> 01:22:12.370 align:middle line:84% MARGARET TIVEY: Do you remember Bill Martin had a whole lecture 01:22:12.370 --> 01:22:15.570 align:middle line:90% on radium and thorium isotopes? 01:22:15.570 --> 01:22:17.090 align:middle line:84% AUDIENCE: Are you saying that it's 01:22:17.090 --> 01:22:19.670 align:middle line:84% how fast it is derived from its parent isotopes? 01:22:19.670 --> 01:22:20.787 align:middle line:90% Is that what you mean by-- 01:22:20.787 --> 01:22:21.620 align:middle line:90% MARGARET TIVEY: Yes. 01:22:21.620 --> 01:22:23.960 align:middle line:84% So radium-224, you're basically producing 01:22:23.960 --> 01:22:27.080 align:middle line:84% much-- radium-224 is being produced much more 01:22:27.080 --> 01:22:28.760 align:middle line:90% rapidly than radium-226. 01:22:28.760 --> 01:22:30.820 align:middle line:84% It's growing in-- it's called growing in-- 01:22:30.820 --> 01:22:32.320 align:middle line:84% AUDIENCE: Another way of saying that 01:22:32.320 --> 01:22:35.760 align:middle line:84% is because radium-224 has a shorter half-life, 01:22:35.760 --> 01:22:39.360 align:middle line:84% when you have a perturbation, it will reach secular equilibrium 01:22:39.360 --> 01:22:43.400 align:middle line:84% with its parent more rapidly than a longer-lived radium 01:22:43.400 --> 01:22:44.960 align:middle line:90% isotope. 01:22:44.960 --> 01:22:46.980 align:middle line:84% And we went through that a little bit, 01:22:46.980 --> 01:22:50.400 align:middle line:84% how long something takes after perturbation to get back 01:22:50.400 --> 01:22:52.200 align:middle line:90% to secular equilibrium. 01:22:52.200 --> 01:22:54.000 align:middle line:84% And that depends upon the half-life 01:22:54.000 --> 01:22:55.460 align:middle line:90% of the daughter isotope. 01:22:55.460 --> 01:23:00.720 align:middle line:90% 01:23:00.720 --> 01:23:03.006 align:middle line:90% MARGARET TIVEY: OK. 01:23:03.006 --> 01:23:07.627 align:middle line:84% And again, it's described fairly well in the lecture notes, 01:23:07.627 --> 01:23:09.960 align:middle line:84% but then you'd also want to go back to the lecture notes 01:23:09.960 --> 01:23:11.800 align:middle line:84% or actually do a problem where you're 01:23:11.800 --> 01:23:13.760 align:middle line:84% using radium isotopes so that you really 01:23:13.760 --> 01:23:14.980 align:middle line:90% understand how it works. 01:23:14.980 --> 01:23:16.730 align:middle line:84% It's tough to understand it the first time 01:23:16.730 --> 01:23:18.860 align:middle line:90% you go through a lecture. 01:23:18.860 --> 01:23:22.540 align:middle line:84% AUDIENCE: How do you distinguish from a radioactive process 01:23:22.540 --> 01:23:26.820 align:middle line:84% versus a kinetic fractionation of different isotopes? 01:23:26.820 --> 01:23:29.380 align:middle line:90% Like, if you're-- 01:23:29.380 --> 01:23:32.403 align:middle line:84% AUDIENCE: But what's the mass difference between radium? 01:23:32.403 --> 01:23:34.820 align:middle line:84% AUDIENCE: Well, sure, it's relatively small, but, I mean-- 01:23:34.820 --> 01:23:36.900 align:middle line:90% AUDIENCE: Very small. 01:23:36.900 --> 01:23:40.060 align:middle line:84% AUDIENCE: But you could presumably measure very small. 01:23:40.060 --> 01:23:41.940 align:middle line:84% AUDIENCE: Well-- well, OK, but the signals 01:23:41.940 --> 01:23:43.440 align:middle line:90% you're seeing are much larger. 01:23:43.440 --> 01:23:43.700 align:middle line:90% AUDIENCE: OK. 01:23:43.700 --> 01:23:43.860 align:middle line:90% MARGARET TIVEY: Right. 01:23:43.860 --> 01:23:45.777 align:middle line:84% AUDIENCE: --can expect by mass fractionation-- 01:23:45.777 --> 01:23:47.500 align:middle line:84% MARGARET TIVEY: And I'm going to-- 01:23:47.500 --> 01:23:49.460 align:middle line:84% AUDIENCE: --in context of what you see? 01:23:49.460 --> 01:23:51.060 align:middle line:84% MARGARET TIVEY: And I'm going to be talking about radioisotopes 01:23:51.060 --> 01:23:52.435 align:middle line:84% a little more in the groundwater, 01:23:52.435 --> 01:23:54.457 align:middle line:84% so let's answer those questions once we've 01:23:54.457 --> 01:23:55.540 align:middle line:90% gone through all of this-- 01:23:55.540 --> 01:23:57.180 align:middle line:84% AUDIENCE: And we'll talk about it more in my section. 01:23:57.180 --> 01:23:57.680 align:middle line:90% MARGARET TIVEY: Oh, you will? 01:23:57.680 --> 01:24:00.300 align:middle line:84% OK, good, because otherwise I won't get to vent fluids. 01:24:00.300 --> 01:24:02.700 align:middle line:90% OK, groundwater. 01:24:02.700 --> 01:24:07.000 align:middle line:84% Groundwater is fairly-- well, it was overlooked for many years. 01:24:07.000 --> 01:24:10.880 align:middle line:84% Basically you have a continent, you have-- just as you-- you 01:24:10.880 --> 01:24:12.620 align:middle line:90% have the oceans here. 01:24:12.620 --> 01:24:14.260 align:middle line:90% You have a continental system. 01:24:14.260 --> 01:24:18.250 align:middle line:90% And you've got some kind of--