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Richard Coupe: Today we’re going to talk
about the National Water-Quality Assessment

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program and part of a component of that is
our Agricultural Chemical Transport study.

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This is a study looking at the effects of
agriculture on water quality at seven different

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sites across the country.

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And today specifically though we’re going
to being talking about an area in Northwest

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Mississippi, our Mississippi Alluvial Plain
commonly referred to as the Delta.

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And we’re going to talk to some farmers,
were going to talk to some scientists and

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we’re going to take a little bit of a tour
of the Delta.

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So Richard what have you been working on as
far as the NAWQA Program?

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Richard Rebich: Well, for the last couple
of years I helped out with sparrow modeling

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that the NWQA Program is doing.

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The team that I worked with help to develop
a SPARROW model for total nitrogen and total

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phosphorous in the south central United States.

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Richard Coupe: So what does a SPARROW model
do?

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Richard Rebich: It relates water-Quality information
that we collect in the field to landscape

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characteristics, sources of a particular pollutant,
and it also relates it to those things that

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deliver those pollutants to a receiving stream.

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Richard Coupe: So what would be the most important
results or the most significant results that

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you found from this study?

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Richard Rebich: The one thing that I thought
was really interesting was how much of the

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nitrogen load was contributed by atmospheric
deposition.

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It was greater than 40 percent.

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So with the other sources of nitrogen and
phosphorous the higher sources came from the

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agricultural industry from fertilizer and
manure inputs.

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Richard Coupe: Does this relate to the Gulf
hypoxia zone at all?

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Richard Rebich: Yes, it would have a pretty
good affect there.

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The hypoxia zone-- recent studies are pointing
towards nutrients as the reasons, and so we're

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in the southern part of the United States
or areas that contribute to the hypoxia zone,

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and we're able to see this as we map the loads
for our particular study area, so that was

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the other thing that we did.

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Richard Coupe: Great.

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Thanks.

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Richard Coupe: Heather, what part of the Agricultural
Chemical Transport study have you really found

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to be interesting?

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Heather Welch: I think it was more of a spinoff
from that project.

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We started looking or we were asked to see
if we could use the data that we had collected

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to see if the biofuels initiative had any
impact on water quality and quantity in the

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Mississippi Delta.

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Richard Coupe: What was the biofuels initiative?

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Heather Welch: Well, it was implemented by
Congress in 2006, and it was to push to make

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gasoline used-- up to 15 percent of it needed
to be ethanol, and in America it's corn-based

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ethanol.

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So we were able to see that between 2006 and
2007 there was a large conversion from cotton

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in the Delta over 450,000 acres were converted
from cotton to corn the following year in

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2007.

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Richard Coupe: So what were the significant
results from this study?

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Heather Welch: So the results were we found
that in that switch from 2006 to 2007 we increased

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I guess the loss of storage in the aquifer,
and in the year 2007 we used more water than

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we would have used had it been in cotton like
the year before.

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Also using the SPARROW model saw that we could
be increasing the amount of nitrogen yield

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leaving from the Yazoo River Basin into the
Mississippi River and then on down to the

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Gulf of Mexico.

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Richard Coupe: Thanks.

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Heather Welch: So what is the most interesting
thing that you've worked on in the Delta as

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a part of ACT study?

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Richard Coupe: I've been working on fate and
transport of glyphosate.

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Glyphosate is a nonselective herbicide used
in the United States for crop production.

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It's been used in the 1970s, but it really
took off in the early 1990s when genetically-modified

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crops specifically corn, cotton and soybean
were modified so that you could use glyphosate

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for weed control.

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And then the amount glyphosate being used
has just jumped up enormously.

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There hasn't been a lot of work on the fate
and transport of glyphosate because it's very

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difficult to analyze for, very expensive.

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But we were able to do a two-year study at
to different locations one in Iowa and one

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in Mississippi looking at multiple-sized basins,
looking at how the fate and transport of glyphosate

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changed as you moved in different agricultural
and climatic areas.

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And we were able to sort of relate the occurrence
of glyphosate to three different factors one

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being use, which makes sense if you use it.

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If you use more of it you're going to see
more of it, and of course in Mississippi because

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of our warmer climate and our heartier weeds
we probably used more than they did in Iowa

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so we saw more.

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Additionally, we saw it was related to hydrology
or precipitation rainfall you need water to

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move agricultural chemicals off the fields.

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So in areas where they have more runoff you'll
see more glyphosate, and the third factor

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was sort of the flow path or the route of
the water as it moves off the field and into

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the stream-- does it go through the ground?
or does it go through over the top of the

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landscape.

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This makes a difference because landscape
has a high affinity to adsorption to soil

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particles, and if it goes through the ground
it has a tendency to adsorb and you'll see

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less glyphosate in your stream if the water
gets there through the soil.

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That's been a very interesting study and it's
been quite well received.

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Richard Coupe: So Jeannie tell us a little
bit about what you've been doing for the Agricultural

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Chemical Transport Study.

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Jeannie Barlow: So I've been working on the
role of groundwater / surface-water exchange

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on the transport of agricultural chemicals
in the Bogue Phalia basin.

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Richard Coupe: And why is this important to
study?

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Jeannie Barlow: Actually at first we thought
it wasn't important to study.

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We've sampled the groundwater in the Delta
and have never found much of any agricultural

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chemicals in the groundwater.

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So the assumption was that there was very
little interaction between the surface water

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and the groundwater since the surface water
always had agricultural chemicals in it of

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some form.

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But what we found is that actually it's not
the hydrology that's preventing the exchange

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of groundwater/ surface water.

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It's the chemistry of our groundwater system.

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So for example in our study area found that
we actually were in connection with the aquifer,

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and we were generally gaining and losing some
movement of water both ways.

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But it was the chemistry within the stream
bed and the aquifer that was actually causing

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nitrogen this example to be reduced in two.

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Richard Coupe: So what are the major conclusions
you found from this study?

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Jeannie Barlow: We find that we have huge
swings in both the direction of the movement

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of water between the groundwater and surface
water, and also that this has a fairly large

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impact on the chemistry of surface water and
could have impact on what we're finding in

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the ground.

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Richard Coupe: Okay, thanks.

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Jeannie Barlow: Thank you.

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Richard Coupe: Claire, what have you been
working on as far as part of the Agricultural

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Chemical Transport Study?

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Claire Rose: I've been working on a paper
regarding metolachlor movement throughout

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the environment.

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Metolachlor is an organic chemical that's
applied as an herbicide, so it's usually applied

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before they plant- it’s pre emergent.

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Richard Coupe: And where is the study area
that you're looking at for this?

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Claire Rose: So you have pretty good coverage
of the United States.

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You have the Mississippi, California in the
San Joaquin Valley, we have study in Maryland

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and a couple in the Midwest.

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We have Indiana and Nebraska, and all these
areas that we were studying are agricultural

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areas.

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So we wanted to understand how the agricultural
chemicals that are applied to increase the

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productivity of crops move throughout the
environment after they're applied, where they

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go and basically have a good idea of what's
going on across the U.S.

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Richard Coupe: So what would be the most significant
results you've found so far?

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Claire Rose: I've found that it's really interesting
that a lot of the areas have similar allocations

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of metolachlor and its degradates throughout
the seven environmental compartments.

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But where you apply metolachlor, where it's
used, you are going to find it or its degradates

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and you're going to find them in every single
environmental compartment through which water

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flows.

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So that's an important thing to keep in mind
about chemicals in the environment.

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Richard Coupe: That's great.

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Thank you.

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Claire Rose: Thank you.

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[End of Audio]

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Duration: 11 minutes

00:10:00.920 --> 00:10:07.449
scientist interviews 2
Richard Coupe, Richard Rebich, Heather Welch,

00:10:07.449 --> 00:10:10.349
Jeannie Barlow, Claire Rose