PROGRAMS AND PROCEEDINGS OF SYMPOSIUM
ON AGRICULTURAL NONPOINT SOURCES OF
CONTAMINANTS: A FOCUS ON HERBICIDES
Sponsored by
U.S. ENVIRONMENTAL PROTECTION AGENCY, REGION VII
U.S. GEOLOGICAL SURVEY, WRD
I
I
a
September 28-29, 1993
Lawrence, Kansas
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PROGRAMS AND PROCEEDINGS OF SYMPOSIUM
ON AGRICULTURAL NONPOINT SOURCES OF
CONTAMINANTS: A FOCUS ON HERBICIDES
Sponsored by
U.S. ENVIRONMENTAL PROTECTION AGENCY, REGION VII
U.S. GEOLOGICAL SURVEY, WRD
s
I
CO
September 28-29, 1993
Lawrence, Kansas
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CONTENTS
PAGE
Agenda .............................. . [[[ 1
Introduction, Moderator: Barb Ryan, U.S. Geological Survey
Organonitrogen Herbicides in Unregulated and Regulated Streams in the Lower
Kansas River Basin, Kansas and Nebraska
By John K. Stamer, U.S. Geological 'Survey.. ;.......: ......... ..... . ............ . .............. .'..6
Impact of the Drinking Water Program on Nonpoint-Soiirce Activities,
By Ralph Langemeier, U.S. Environmental Protection Agency ............................ 7
Basic Principles of Pesticide Runoff
By John Hickman, Kansas State University [[[ 8
Occurrence in Surface Water and Ground Water, Moderator: Ronald F.
Hammerschmidt, Kansas Department of Health and Environment
Occurrence and Transport of Pesticides in the Mississippi River Basin
By Donald Goolsby and W.A. Battaglin, U.S. Geological Survey ......................... 9
Missouri River Monitoring for Pesticides
By Terry L. Gloriod and Paul W. Keck, St. Louis County Water Company ........ 10
Occurrence of Herbicides in Water from Rural Domestic Wells, Northwest and
Northeast Missouri, July 1991 and July 1992
By Donald H. Wilkison, U.S. Geological Survey, and Randall D. Maley,
University of Nebraska - Lincoln [[[ 11
Pesticide Persistence in Two Impoundments in Northeastern Nebraska
By Daniel D. Snow and Roy F. Spalding, University of Nebraska - Lincoln ....... 12
Determining the Age, Transport, and 3-Dimensional Distribution of Atrazine in a
Reservoir by Immunoassay
By James D. Fallen and E.M. Thurmah, U.S. Geological Survey ............ .. ..... '... 13
Occurrence and Control of Atrazine and its Degradation Products in Public Drinking
Water Supplies
By Stephen J. Randtke, University of Kansas .................................................. 14
Herbicide Distribution Beneath Nebraska MSEA Blocks
By Roy F. Spalding and Thomas D. Papiemik, University of Nebraska -
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CONTENTS-Continued
PAGE
Fate and Transport, Moderator: U. Gale Hutton, Nebraska Department of
Environmental Quality
17
Herbicide Transport and Degradation in a Pristine Watershed: The Fate of Herbicides
Deposited By Precipitation
ByAron E. Cromwell and E. Michael Thurman, U.S. Geplogical Survey ...........
A Comparison of Atrazine and Metolachlor. Biological Assessment Data to
Concentrations Reported in Precipitation Monitoring Studies
By Philip Banks, MARATHON, and Dennis P. Tierney, Ciba Plant Protection .. 18
Chemistry, Degradation, and Transport of Triazine Metabolites in Surface Water
By E.M. Thurman, U.S. Geological Survey
19
Nonequilibrium Adsorption and Degradation of Atrazine and Alachlor in Soil
By Gerard J. Kluitenberg, Leticia S. Sonon, and A. Paul Schwab, Kansas State
University ..................................... - [[[ 20
Cyanazine Metabolites in Surface Water: The Transport and Degradation of Labile
Herbicides
By M.T. Meyer and E.M. Thurman, U.S. Geological Survey .............................. 21
Biodegradation of Pesticides in Subsurface Samples from Three Midcontinent Sites
By James L. Sinclair, and Tony R. Lee, ManTech Environmental Technology,
Inc., Robert S. Kerr Environmental Research Laboratory ................................. 22
Health and Ecological Effects, Moderator: Darrell McAllister,
Iowa Department of Natural Resources
Incidence of Certain Cancers and Exposure to Agricultural Herbicides: Measures
to Reduce Risk
By Robert J. Robel, Kansas State University, Frederick F. Holmes and
-. Cathy. D. Boysen, University of Kansas Medical Center ...................................
23
Hazard Assessment of Atrazine
By Darrell D. Sumner, Charles B. Breckenridge, and James T. Stevens, Ciba
Plant Protection ......... , ....... [[[ ............. 24
Ecological Impacts of Herbicides-A Review
by Donald Huggins, Kansas Biological Survey
25
Management Options, Moderator: Nicholas A. Di Pasquale, Missouri
Department of Natural Resources and Dale Lambley,
Kansas State Board of Agriculture
Weed Control Options for Reducing Atrazine Impact
By David L. Regehr, Kansas State University [[[ 26
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CONTENTS-Continued
PAGE
Pesticide Incorporation and Tillage Affects Atrazine and Alachlor Losses
By James Steichen, Philip Barnes, and Hirozumi Watanabe, Kansas State
University, and Elbert Dickey, David Shelton, Paul Jasa, and Nathan
Watermeier, University of Nebraska - Lincoln 28
Impact of Conservation Practices on Agricultural Nonpoint Contamination
By Philip Barnes, Kansas State University, Mike Pope and Andy Foster,
U.S. Geological Survey '.: .: 29
Federal, State, and Local Cooperation to Improve Surface-Water and Ground-Water
Quality: A Case Study from Recharge Lake in York County, Nebraska
By Robert A. Dunlevy, U.S. Environmental Protection Agency 30
Management of Herbicides in the Delaware River Basin
By Jane Nieuhues, Steering Committee for the Non Point Pollution Plan for the
Delaware River Basin 31
West Lake Water Quality Project
By Alan Teel, Iowa State University of Science and Technology 32
Influence of Management Practices on Water Quality in Walnut Creek Watershed
By J.L. Hatfield, R.C. Buchmiller, P.J. Soenksen, and D.B. Jaynes,
U.S. Department of Agriculture and U.S. Geological Survey 33
Utilizing Fertilizer and Chemical Dealers to Manage Pesticides
By Duane Sand, Long Range Planning and Research, Iowa Natural Heritage
Foundation 34
Posters
Water-Quality Characteristics of Stormwater Runoff in Davenport, Iowa
By Bryan D. Schaap and Keith J. Lucey, U.S. Geological Survey 36
Isocratic Separation of Alachlor Ethane and Sulfonic Acid, Alachlor Oxacetic Acid, and
Hydroxyatrazine by Reversed-P.hase Liquid Chromatography
By M. L. Pomes, D. F. Holub, and E.M. Thurman, U.S. Geological Survey 37
Chromatographic Applications of Solid-Phase Extraction in Developing Immunoassay
Methods for Herbicides and Their Metabolites: An Example for Alachlor and
Alachlor-Ethanesulfonic Acid
By D.S. Aga and E.M. Thurman, U.S. Geological Survey 38
Use of Geographic Information System Procedure to Estimate Atrazine Impact
By John S. Hickman, Ray E. McDonald, H.L. Seyler, and Michel D. Ransom,
Kansas State University 39
Estimating Pollutant Soil Ratings
By John S. Hickman, Paul R. Finnell, and Richard L. Schlepp, Kansas State
University and U.S. Soil Conservation Service 40
ill
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CONTENTS-Continued
PAGE
Reconnaissance of Data for Herbicides and Their Metabolites in Surface Water of the
Midwestern United States: Immunoassay and Gas Chromatography/Mass
Spectrometry
By Elisabeth A. Scribner, E. Michael Thurman, and Donald A. Goolsby,
U.S. Geological Survey .::. - 41
Atrazine Management to Meet Water-Quality Criteria
By David L. Regehr, Dallas E. Peterson, and John S. Hickman, Kansas State
University » '' ^ ' 42
Effects of Pore-Size Distribution and Saturation Cycles on Atrazine and Bromide
Transport Through Soil
By E.A. Smith, P.J. Shea, W.L. Powers, and D.R. Tupy, University of Nebraska
-Lincoln , 43
Selected Herbicides in Bottom Sediments and Water of Water-Supply Lakes in Iowa,
By S.J. Kalkhoff, J. Kennedy, U. Agena, and G. Breuer, U.S. Geological Survey,
University of Iowa Hygenic Laboratory, and Iowa Department of Natural
Resources 44
The Comprehensive Environmental Economic Policy Evaluation System: An
Application to Atrazine and Water Quality
By Aziz Bouzaher, Center for Agricultural Rural Development and Andrew
Manale, U.S. Environmental Protection Agency 45
Presenter addresses 46
iv
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AGENDA
SYMPOSIUM ON AGRICULTURAL NONPOINT
SOURCES OF CONTAMINANTS:
A FOCUS ON HERBICIDES
Holiday Inn -
2OO McDonald Drive
Lawrence, Kansas
September 28-29, 1993
September 28, 1993
11:00 AM Registration
12:30 PM Introductions - Barb Ryan, U.S. Geological Survey
12:40 Organonitrogen Herbicides in Unregulated and Regulated Streams, in
the Lower Kansas River Basin, Kansas and Nebraska
John Stamer, U.S. Geological Survey
1:20
1:40
Impact of the Drinking Water Program on Nonpoint Source Activities
Ralph Langemeier, U.S. Environmental Protection Agency, Region
VII
Basic Principles of Pesticide Runoff
John Hickman, Kansas State University
OCCURRENCE IN SURFACE WATER AND GROUND WATER
Moderator: Ronald F. Hammerschmidt
Division of Environment
Kansas Department of Health and Environment
2:00
2:20
2:40
Occurrence and Transport of Pesticides in the Mississippi River Basin
Donald A. Goolsby and W.A. Battaglin, U.S. Geological Survey
Missouri River Monitoring for Pesticides
Terry L. Gloriod and Paul W. Keck, St. Louis County Water Com-
pany
BREAK
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3:00
3:20
3:40
4:00
4:20
4:40
5:00
5:15
7:00
Occurrence of Herbicides in Water from Rural Domestic Wells,
Northwest and Northeast Missouri, July 1991 and July 1992
Donald H. Wilkison, U.S. Geological Survey, Randall D. Maley,
Missouri Department of Health
Pesticide Persistence in Two Impoundments in Northeastern
Nebraska
Daniel D. Snow and Roy F. Spalding, University of Nebraska-
Lincoln .
Determining the Age, Transport, and 3-Dimensional Distribution of
Atrazine in a Reservoir by Immunoassay
James D. Fallon and E.M. Thurman, U.S. Geological Survey
Occurrence and Control of Atrazine and its Degradation Products in
Public Drinking Water Supplies
Stephen J. Randtke, University of Kansas
Herbicide Distribution Beneath Nebraska MSEA Blocks
Roy F. Spalding and Thomas D. Papiernik, University of Nebraska-
Lincoln
A Natural Gradient Transport Study of Selected Herbicides
Sharon K. Widmer and R.F. Spalding, University of Nebraska-
Lincoln
BREAK
Poster Session and Cash Bar
Adjourn
September 29, 1993
FATE AND TRANSPORT
Moderator: U. Gale Hutton
Water Quality Division
Nebraska Department of Environmental Quality
8:00 AM Herbicide Transport and Degradation in a Pristine Watershed: The
Fate of Herbicides Deposited by Precipitation
Aron E. Cromwell and E. Michael Thurman, U.S. Geological Survey
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8:20
8:40
9:00
9:20
9:40
10:00
A Comparison of Atrazine and Metolachlor Biological Assessment
Data to Concentrations Reported in Precipitation Monitoring Studies
Philip A. Banks, MARATHON-Agricultural and Environmental
Consulting, Inc., and Dennis P. Tierney, Ciba-Geigy Corporation
Chemistry, Degradation, and Transport of Triazine Metabolites in
Surface Water
E.M. Thurman, U.S. Geological Survey
Nonequilibrium Adsorption and Degradation of Atrazine and Alachlor
in Soil
Gerard J. Kluitenberg, Leticia S. Sonon, and A. Paul Schwab,
Kansas State University
Cyanazine Metabolites in Surface Water: The Transport and
Degradation of Labile Herbicides
M.T. Meyer and E.M. Thurman, U.S. Geological Survey
Biodegradation of Pesticides in Subsurface Samples from Three
Midcontinent sites
James L. Sinclair and Tony R. Lee, Robert S. Kerr Environmental
Research Laboratory
BREAK
HEALTH AND ECOLOGICAL EFFECTS
Moderator: Darrell McAllister
Surface and Groundwater Protection Bureau
Iowa Department of Natural Resources
10:30 Incidence of Certain Cancers and Exposure to Agricultural
Herbicides: Measures to Reduce the Risk
Robert J. Robel, Kansas State University, Frederick F. Holmes and
Cathy D. Boysen, University of Kansas Medical Center
10:50 Hazard Assessment of Atrazine
Darrell D. Sumner, Charles B. Breckenridge, and James T. Stevens,
Ciba-Geigy Corporation
11:10 Ecological Impacts of Herbicides-A Review
Don Huggins, Director, Aquatic Ecotoxicology Program,
Kansas Biological Survey
11:30 LUNCH
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1:00 PM
1:20
1:40
2:00
2:20
2:40
MANAGEMENT OPTIONS
Moderator: Nicholas A. Di Pasquale
Water Pollution Control Program
Missouri Department of Natural Resources
Weed Control Options for Reducing Atrazine Impact
David L. Regehr, Kansas State University
Impact of Conservation Tillage Systems on Agricultural Runoff
Douglas W. Rushing, Monsanto Agricultural Company
Pesticide Incorporation and. Tillage Affects Atrazine and Alachlor
Losses
James Steichen, Hirozumi Watanabe, Kansas State University,
Elbert Dickey, David Shelton, Paul Jasa, and Nathan Watermeier,
University of Nebraska-Lincoln
Impact of Conservation Practices on Agricultural Nonpotnt
Contamination
Philip L. Barnes, Kansas State University, Mike Pope and Andy
Foster, U.S. Geological Survey
Federal State, and Local Cooperation to Improve Surface Water and
Groundwater Quality: The York Ground Water Recharge Project
Robert A. Dunlevy, U.S. Environmental Protection Agency, Region
VII
BREAK
Moderator: Dale Lambley
Kansas State Board of Agriculture
3:00
3:20
3:40
.Management of Herbicides in the Delaware River Basin
Jane Nieuhues, Non Point Source Pollution Plan for the Delaware
River Basin
West Lake Water Quality Project
Alan Teel, ICM Coordinator, Iowa State University Extension
Service, Osceola, Iowa
Influence of Management Practices on Water Quality in Walnut Creek
Watershed
J.L. Hatfield and D.B. Jaynes, U.S. Department of Agriculture,
R.C. Buchmiller, P.J. Soenksen, U.S.Geological Survey
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4:00
4:20
5:00
Utilizing Fertilizer and Chemical Dealers to Manage Pesticides
Duane Sand, Director, Long Range Planning and Research,
Iowa Natural Heritage Foundation
Open discussion, wrapup
Larry Ferguson and Richard Herbert
Adjourn
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ORGANONITROGEN HERBICIDES IN UNREGULATED AND
REGULATED STREAMS IN THE LOWER KANSAS RIVER BASIN,
KANSAS AND NEBRASKA
John K. Stamer, U.S. Geological Survey, Lawrence, Kansas
Atrazine has been the most extensively applied herbicide in the lower Kansas River Basin, which
drains 39,627 square kilometers of predominantly agricultural land in northeast Kansas and
southeast Nebraska. As part of the U.S. Geological Survey's National Water-Quality Assessment
(NAWQA) Program, the spatial and temporal distributions of organonitrogen herbicides in surface
water were denned. Results indicated that, in principal streams of the basin, atrazine was the most
frequently detected organonitrogen herbicide and occurred in the largest concentrations. The
larger atrazine concentrations were measured in parts of the basin where the larger amounts of
atrazine had been applied. Atrazine concentrations varied seasonally; the larger concentrations
occurred in the spring and summer and the smaller in the fall and winter. Reservoirs decreased
the seasonal variability of atrazine concentrations from that of inflowing streams.
Atrazine poses a problem for public-water supplies because it is water soluble, relatively persistent
in the hydrologic system, and not effectively removed by conventional water-treatment practices.
The U.S. Environmental Protection Agency has established a Maximum Contaminant Level (MCL)
for atrazine 3.0 (ig/L in finished public drinking-water supplies. The 1989 mean concentration of
atrazine in the outflow of Perry Lake exceeded the MCL even though streamflows in the Delaware
River during 1989 were only about 20% of the long-term mean. Results of the NAWQA study were
used by the Kansas State Board of Agriculture as a basis for designating the Delaware River Basin
as the Nation's first inland surface-water pesticide management area (PMA).
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IMPACT OF THE DRINKING WATER PROGRAM ON NONPOINT-
SOURCE ACTIVITIES
Ralph N. Langemeier, U.S. Environmental Protection Agency, Kansas City, Kansas
Phase n Rule - On January 30, 1991, EPA.promulgated regulations that established Maximum
Contaminant Levels (MCLs) for a variety of pesticides and other contaminants, including a level of
3 |ig/L for atrazine. This regulation went into effect in. July of 1992. Public water systems are to
conduct quarterly monitoring for atrazine and the other contaminants between January 1993 and
December 1995. Systems are in compliance .with these regulations if the annual average
concentration is below the MCL.
Based on studies conducted by various water suppliers, State and Federal agencies prior to the
start of the official monitoring, it is anticipated that many surface-water systems in the Midwest
will have difficulty meeting the atrazine MCL without treatment. Public water supplies that rely on
reservoirs are likely to have more problems meeting the atrazine MCL than those that take water
directly from rivers. There are approximately 150 surface-water systems in EPA Region VII that
use reservoirs.
Phase V Rule - The Phase V regulations promulgated on July 17, 1992, added 5 inorganic
chemicals and 18 synthetic organic chemicals (SOCs) to the list of regulated contaminants. The
list of 18 SOCs include such chemicals as Dinoseb, Diquat, Endothall, Glyphospate and Simazine.
The Phase V monitoring coincides with the Phase II rule.
Surface Water Treatment Rule - The Surface Water Treatment Rule will also have an impact on
nonpoint-source activities. It requires, among other things, that State primacy agencies determine
if public water systems that are using ground water, e.g. wells and springs, are under the direct
influence of surface water. For instance, does nearby surface water affect the quality of the well
water? The State has until June of 1994 to make those decisions on community water systems. It
is anticipated that many public water systems that use alluvial aquifer wells may be affected.
If a ground water source is determined to be under the influence of surface water, the public water
system must provide the same level of treatment as traditional surface-water systems, which may
include filtration and disinfection. Treatment must be in place within 18 months from the time the
public water system is notified of the decision. Systems wishing to avoid expensive treatment may
be required to implement watershed protection programs.
The secondary impact of these decisions is that a State may revise it's ambient water-quality
standards water-body designation for those surface waters that are influencing wells to include a
public drinking-water supply use. This, in turn, could have a significant effect on the nonpoint-
source program. For instance, the priorities for the State and Federally funded nonpoint-source
projects could be altered, and the level and type of prevention/control activities could be affected.
Future Surface Water Treatment regulations being considered by EPA may require public water
systems to do extensive evaluations of their source water, including the watershed, to identify and
address potential sources of contamination. Of particular concern are microbiological
contaminants, such as Giardia, Cryptosporidium, and E. Coli bacteria; all have links to
agricultural activities.
The EPA Region VII office is involved in various activities to inform those involved with nonpoint-
source pollution prevention and control activities about the drinking-water regulations and their
impact. These outreach efforts will help States establish priorities in their nonpoint-source
management programs.
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BASIC PRINCIPLES OF PESTICIDE RUNOFF
John S. Hickman, Kansas State University, Manhattan, Kansas
Understanding basic principles of pesticide runoff is key to designing and implementing
management practices to reduce surface loss of pesticides. There are a variety of practices that can
be used to reduce pesticide runoff; however, the effectiveness of these factors will vary from one
site to another.
The amount of pesticides lost in surface rtinoff will vary depending on three-key factors. The first
factor is that most pesticides are partitioned into the adsorbed (sediment) and/or the solution
(water) phase of runoff. Pesticides with a solubility of greater than 2 ppm are typically lost with the
water leaving the field. Some exceptions to this rule are pesticides with both a high solubility and
adsorption coefficient such as paraquat or Roundup. An even better rule of thumb is that
pesticides with an adsorption coefficient (Koc) less than 1,000 are typically lost in the solution or
water phase. Atrazine has a solubility of 33 ppm and Koc of 100 and thus is lost in the water that
leaves the field. In some recent modelling using the GLEAMS model, about 90 percent of 232
pesticides modelled were lost primarily in the solution phase of runoff. For most pesticides,
controlling runoff that leaves the field is more important than sediment control for reducing loss in
overland flow. Fortunately, some of the soil-erosion control practices used today also reduce runoff
and thus are somewhat effective in reducing pesticide losses.
The second key factor is the concept of a "mixing zone," a zone where pesticide, soil, overland flow,
and precipitation intermix to create runoff. This zone is at the soil surface and is very narrow,
often less than one-third of an inch in thickness. The concentration of pesticide in the mixing zone
often controls the amount lost in overland flow. Once the product moves below this depth, there is
a much smaller chance for the pesticide to be lost in overland flow. Soils that are coarse-textured
and/or have low amounts of organic matter often have lower pesticide concentrations in the
mixing zone. Incorporation and reducing application rates will also reduce the pesticide
concentration in the mixing zone. Incorporation will result in a 50 to 70% reduction in pesticide
surface loss as compared to a surface application.
The third factor affecting pesticide runoff loss is the characteristic of the first precipitation/runoff
event after application. Critical storms that have historically proven to have the largest pesticide
runoff, losses are those that occur within 2 weeks of application, have at least half an inch of rain,
arid have 50% runoff or greater. Storm patterns differ across the country. In Kansas, such storms
are more likely to occur in May or June as compared to March or early April. Timing of application,
therefore, can have a large effect on pesticide surface losses. Another important runoff-related
factor is the time to runoff after rainfall begins. Any factor or practice that delays the time to runoff
will help move the pesticide below the mixing zone and reduce runoff losses. Conservation tillage
and contouring are examples of conservation practices which delay the time to runoff and reduce
overland flow losses.
In summary, properties of the soil, pesticides, site, and climate as well as conservation and
management practices will affect the amount of pesticide runoff. Management plans to reduce
pesticide surface loss will vary from one site to another. Management practices, such as changing
rate of application, timing, and placement, and conservation practices, such as conservation
tillage and contouring, can all reduce pesticide surface loss.
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OCCURRENCE AND TRANSPORT OF PESTICIDES IN THE
MISSISSIPPI RIVER BASIN
D.A. Goolsby and W.A. Battaglin, U.S. Geological Survey, Lakewood, Colorado
The Mississippi River Basin contains the largest and most intensive agricultural region in the
Nation. Large amounts of pesticides (herbicides, insecticides, and fungicides) are used in order to
increase yields from the major crops grown.in the basin (corn, soybeans, sorghum, wheat). About
two-thirds of all pesticides used annually for agriculture in the United States are applied to
cropland and pastureland .in the Mississippi .River Basin. Herbicides, account for about three-
fourths of the annual pesticide use and are the most frequently detected pesticides in streams
throughout the basin.
Recent regional-scale studies by the U.S. Geological Survey have shown that significant amounts
of herbicides are flushed into streams by late spring and summer rainfall following application of
herbicides to cropland. These amounts are large enough to produce high concentrations of several
herbicides in streams for a few weeks to several months during periods of storm runoff.
Concentrations of herbicides in some small streams may briefly exceed 50 ng/L, and annual
average concentrations may exceed drinking-water standards established under the Safe Drinking
Act. Flow from these small streams, in turn, transports significant amounts of pesticides into large
rivers such as the Missouri, Ohio, and Mississippi, and eventually to the Gulf of Mexico. During
1991 and 1992, more than 40 pesticides and pesticide degradation products were detected in the
main stem of the Mississippi River, although most of these were detected in very low
concentrations (less than 0.5 (ig/L). Maximum concentrations of the most extensively used
herbicides such as alachlor, atrazine, cyanazine, and metolachlor, in the Missouri, Ohio, and
Mississippi Rivers ranged from 3 to 10 ng/L and exceeded health-based limits for drinking water
for periods as long as one month at some locations. However, the annual average herbicide
concentrations in these large rivers were far below health-based limits, and concentrations did not
violate the Safe Drinking Water Act. Low concentrations (0.005 to 0.2 ng/L) of atrazine, cyanazine,
and metolachlor were detected throughout the year in the Mississippi River due, in part, to storage
and subsequent discharge of these compounds from lakes, reservoirs, and aquifers.
The total mass of pesticides discharged annually from the Mississippi River represents a small
fraction of the total amounts applied to cropland in the basin. The atrazine and cyanazine
discharged to the Gulf of Mexico 'during April 1991 through March 1992 was equivalent to about
1:6%'of the .amounts applied annually in the basin. The quantities of several other'herbicides
discharged annually from the basin, expressed as a percentage of the amount applied, were:
metolachlor, 0.8%; alachlor. 0.2%: and simazine, 2.7%. Most of the herbicide transport occurs
during May, June, and July. More than one-half of the total quantity of pesticides transported
annually by the Mississippi River originates in small streams draining Iowa, Illinois, and parts of
Missouri and Minnesota, an area that constitutes only about 22% of the Mississippi River drainage
basin.
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MISSOURI RIVER MONITORING FOR PESTICIDES
T.L. Gloriod and P.W. Keck, St. Louis County Water Company, St. Louis, Missouri
During the 1980's, laboratory improvements in instrumentation and methods provided the means
for reliable measurement of many pesticides/herbicides in water. Subsequent monitoring by water
utilities on the Missouri River during spring and summer runoff periods identified four commonly
occurring compounds; atrazine, alachlor, metolachlor, and cyanazine. A 1990 study by the St.
Louis County Water Company analyzed atrazine levels each day during May, June, and July at a
single location on the Missouri River. . , ,
In January 1991, the USEPA finalized drinking-water standards for atrazine and alachlor. During
the spring and summer of that year, the Missouri River Public Water Supplies Association
(MRPWSA) conducted a comprehensive monitoring study on the Missouri River to determine the
occurrence, range of concentrations, and regional contribution of these two pesticides. Atrazine
and alachlor concentrations were measured in daily samples from seven sites that were near
Corps of Engineers gaging stations. The study report presents the occurrence pattern at each site,
and the mass of pesticide contributed by major tributary regions. The study was repeated in 1992,
using fewer sampling sites.
While the concentration of atrazine can vary widely from day to day, the total amount of atrazine
discharged from the Missouri River did not change dramatically during the 3 years of study.
During 1990, 118,456 pounds of atrazine were discharged from the Missouri; during 1991,
106,230 pounds; and in 1992, 88,363 pounds.
The occurrence data collected by the MRPWSA members are important in assessing the potential
impact on water systems who must comply with the drinking-water standards that have been
established.
Conventional water-treatment plants on the Missouri River are only marginally effective in
reducing pesticide levels in river water. Drinking-water compliance monitoring using quarterly
samples, has a high probability of producing average levels that exceed the drinking-water
standards especially in lower volume tributaries. Granular activated carbon, if required for
treatment of pesticides, will dramatically increase water pricing for consumers.
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OCCURRENCE OF HERBICIDES IN WATER FROM RURAL
DOMESTIC WELLS, NORTHWEST AND NORTHEAST MISSOURI,
JULY 1991 AND JULY 1992
Donald H. Wilkison, U.S. Geological Survey, Independence, Missouri, and
Randall D. Maley, Missouri Department of Health, Jefferson City, Missouri
In July 1991, the U.S. Geological Survey and the Missouri Department of Health sampled water
from 130 rural .domestic wells in Caldwell, Clinton, Daviess, Gentry, and Nodaway Counties in
northwest 'Missouri. These water samples were analyzed for the-'presence of trlazine- and Cl-
acetamide herbicides using enzyme-linked immunosorbent assays. Triazine or Cl-acetamide
herbicides were detected at concentrations higher than 0.05 \ig/L in one-third of all samples.
Samples from 79 wells were analyzed using gas-chromatograph/mass spectrometry methods. One
or more of the herbicides alachlor, atrazine, cyanazine, metribuzin, metolachlor, and trifluralin
were detected at concentrations greater than or equal to 0.05 |ig/L in samples from 19 of the 79
wells. Atrazine was detected in samples from 16 of the wells in concentrations that ranged from
0.05 to 9.6 n.g/L. Atrazine concentrations exceeded 3.0 \ig/L in only one sample.
In July 1992, water samples were collected from 147 wells in Audrain, Clark, Lewis, Monroe,
Scotland, and Shelby Counties in northeast Missouri. Alachlor, atrazine, cyanazine, metribuzin,
and metolachlor were detected at concentrations greater than 0.10 ng/L in water samples from 19
of the 147 wells sampled. Atrazine was detected in water from 18 of the 19 wells with detectable
herbicide concentrations. Atrazine concentrations exceeded 3.0 ^g/L in two of the samples.
Well depth, well diameter, and geology were significant factors in the occurrence of herbicides in
water from wells sampled in northeast Missouri. For wells with detectable concentrations of
herbicides in the water samples, well depths ranged from 12 to 220 feet, and averaged 58.9 feet.
For wells with no detectable concentrations of herbicides, well depths ranged from 15 to 740 feet,
and averaged 211 feet. The diameter of wells with detectable concentrations of herbicides in the
water samples ranged from 1.5 to 144 inches, and averaged 33.2 inches. For wells with no
detectable herbicide concentrations in the water samples, the well diameter ranged from 1.5 to 72
inches, and averaged 14.7 inches. Although only 21% of the 147 wells sampled during July 1992
were screened in rocks of Pennsylvanian age of the Cherokee Group, these wells accounted for
60% of the wells with detectable concentrations of herbicides in the water samples. The rest of the
wells sampled were screened in Ordovician- or Mississippian-age rocks, alluvium of the Des
Mpines or Mississippi Rivers, or glacial till.
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PESTICIDE PERSISTENCE IN TWO IMPOUNDMENTS IN
NORTHEAST NEBRASKA
Daniel D. Snow and Roy F. Spalding, University of Nebraska-Lincoln, Lincoln, Nebraska
Dissolved pesticide concentrations in 108 water samples collected from two closely spaced lakes
between early May 1990 and mid-June 1991 indicated large differences in impacts from watershed
nonpoint-source inputs. Pesticide levels in Maskenthine Lake, a small impoundment of only 34
hectares, increased dramatically in response to- spring and early summer runoff .events. Fifteen
pesticides (atrazine, alachlor, metolachlor, cyanazine, EPTC, butylate, propachlor, trifluralin,
simazine, prometon, propazine, fonofos, disulfoton, metribuzin, and terbufos) and two atrazine
metabolites, deethylatrazine (DEA) and deisopropylatrazine (DIA), were detected. Atrazine,
cyanazine, DEA, and DIA levels were greater than 1 (ig/L"1. Atrazine remained above the Maximum
Contaminant Level for potable water of 3 |ig L"1 throughout the period of investigation. The
pesticide response to spring and summer runoff events was much less dramatic at Willow Lake, a
284-hectare impoundment. All of the 15 pesticides and two metabolites detected in Maskenthine
Lake, except terbufos and disulfoton, were detected in Willow Lake. However, the concentrations
were lower and did not .exceed 1 |ig L"1. In months following the maximum flush of pesticides in
May and June there was a significant decrease in pesticide residues that appeared to follow first-
order kinetics. Apparent half-lives were calculated from the observed decrease. Atrazine was the
most persistent agrichemical (t1'/2 = 133, t1/2 = 148) introduced in the spring runoff events.
Extracted pesticide levels were also higher in bottom cores from Maskenthine Lake. Differences in
pesticide levels in the two lakes were related to watershed slope, soil-drainage capacity, land use,
and rainfall.
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DETERMINING THE AGE, TRANSPORT, AND 3-DIMENSIONAL
DISTRIBUTION OF ATRAZINE IN A RESERVOIR BY
IMMUNOASSAY
James D. Fallen and E.M. Thurman, U.S. Geological Survey, Lawrence, Kansas
The age, transport, and distribution of atrazine in a reservoir were determined using enzyme-
linked immunosorbent assay. A pulse-of stormwater runoff containing atrazine concentrations as
much as nine times larger than .the U.S. Environmental Protection Agency Maximum Contaminant
Level (MCL) for drinking water (the MCL for atrazine is based on an annual average concentration
of 3.0 ng/L was monitored as it moved through Perry Lake, northeastern Kansas, during the 1992
growing season. The drainage basin of Perry Lake is the first Pesticide Management Area
designated by the State of Kansas. The leading edge of the pulse marked the boundary and mixing
zone between old atrazine applied in previous years and freshly applied atrazine. Deethylatrazine-
to-atrazine ratios (DAR) further denned the age of atrazine in the reservoir. Runoff entering the
reservoir immediately after herbicide application was identified by its small DAR values (0.09 to
0.13). Water with increasing DAR values (0.14 to 0.25) entered the reservoir as the year progressed
and gradually displaced 'water with smaller DAR values. Four hundred and twenty (420) samples
from four detailed reservoir surveys (pre-application, post-application, summer, and autumn) were
analyzed by immunoassay to determine the distribution of herbicide concentrations in the
reservoir. Also, weekly samples were collected from four fixed sites located upstream, within, and
downstream of the reservoir. One hundred (100) of these samples were analyzed by gas
chromatography/mass spectrometry to confirm immunoassay results and to determine
deethylatrazine and deisopropylatrazine concentrations: A combination of immunoassay and DAR
values could prove useful in developing reservoir-release strategies to mitigate atrazine
concentrations in reservoirs and their outflows.
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OCCURRENCE AND CONTROL OF ATRAZINE AND ITS
DEGRADATION PRODUCTS IN PUBLIC DRINKING
WATER SUPPLIES
Stephen J. Randtke, University of Kansas, Lawrence, Kansas
Atrazine is frequently detected in municipal water supplies, at times above the Maximum
Contaminant Level (MCL) of 3 Mg/L promulgated by the U.S. EPA. Atrazine's, degradation products
have toxicological properties similar to those of atrazine and may eventually be regulated. Little is
known regarding the occurrence of these compounds in drinking water, the possibility of their
formation during treatment, or methods for their removal.
This presentation will summarize the results of a 2-year study that focused on the types and
concentrations of atrazine degradation products present in raw and treated drinking-water
samples collected from seven treatment facilities located in the midwestem United States
Treatment processes studied included adsorption on powdered and granular activated carbon
(PAC and GAC), oxidation (using ozone, potassium permanganate, chlorine, or chlorine dioxide),
and ion exchange. Point-of-use activated carbon filters were also evaluated. Atrazine and its major
degradation products were determined using solid-phase extraction and high-pressure liquid
chromatography.
Atrazine concentrations in water supplies drawn from streams peaked in late spring to early
summer; those in supplies drawn from lakes or reservoirs were relatively constant. The
concentrations of degradation products in streams were less variable and significantly lower than
those of the parent compound. Hydroxyatrazine was the most abundant degradation product
detected, averaging about 1 ng/L (versus about 3 |ig/L for atrazine). Deethylatrazine and
deisopropylatrazine were routinely detected, but at concentrations averaging only 0.7 and 0.3
Mg/L, respectively. Didealkyatrazine and the deethylated hydroxanalogues were not detected.
Conventional treatment processes did not achieve substantial removal or alteration of atrazine or
its degradation products. PAC addition resulted in substantial removal of atrazine and its
degradation products; i.e., about 30 to 90%, depending on the dosage applied. At the Rathbun,
Iowa, treatment facility, a 2-foot cap of GAC removed 24% of the influent atrazine and between 9
and 31% of the atrazine degradation products. At Perry Lake, Kansas, a GAC system installed by
the tiJ.S:- Army Corps of Engineers achieved complete removal of atrazine and its degradation
products during April through September of its first year in service. Some point-of-use GAC
systems effectively removed atrazine and its degradation products from tap water throughout the
stated life of the unit; others experienced premature breakthrough, and breakthrough of atrazine
correlated with breakthrough of residual chlorine.
Potassium permanganate reacts too slowly with atrazine and its major degradation products to
cause a significant change in their concentration under typical water-treatment conditions.
Atrazine and its major degradation products were adsorbed by a strong-acid cation-exchange
resin, but they were chromatographically displaced by calcium.
The concentrations of atrazine and its degradation products in surface-water supplies are variable,
which has significant implications for both monitoring and control. Fortunately, it appears that
the degradation products occur at lower concentrations than the parent compound and that their
removal by most non-oxidative processes is similar to that of atrazine. However, oxidative
processes tend to convert atrazine to uncleaved degradation products that may be no less toxic to
humans. Adsorption, especially on PAC, appears to be the best means of control based on the
information now available.
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HERBICIDE DISTRIBUTION BENEATH NEBRASKA
MSEA BLOCKS
Roy F. Spalding and Thomas D. Papiernik, University of Nebraska-Lincoln,
Lincoln, Nebraska
Sampling of 41 multilevel sampler installations occurred in early spring, summer, and fall and
represents times of maximum and minimum water levels, from July 1991 to October 1992, a total
of 2,200 discrete samplings for nitrate and atrazine and its. degradates were, used to calculate
average concentrations at each depth.. Initially, nitrate-N concentrations in pore water beneath the
root zone (unsaturated zone) to the bottom of the primary aquifer were invariant with depth.
Atrazine concentrations were stratified with average concentrations of -3 ng/L in the shallow
water and ~1 ng/L at depth. Both deethyl- and deisopropylatrazine decrease at almost the same
rates as the parent compound, suggesting that hydrolysis is the primary process controlling
atrazine concentrations. Deethylatrazine concentrations are about 30% higher than atrazine
concentrations throughout the profiles. 3H/3He dates suggest that the ground water at the bottom
of the primary aquifer to be from 10-20 years old. Irrigation water is drawn primarily from the
lower part of the primary aquifer because the irrigation wells are screened in the lower one-third of
the aquifer. Through the October 1992 sampling, water-table fluctuations of 1.5 meters (5 feet)
occurred annually, and declines from irrigation were normally compensated by recharge in the
winter and spring. A decrease in aquifer NO3-N concentration was not noted until the spring 1993
sampling. High recharge rates during a very wet spring and early summer of 1993 have aided the
remediation of the upper portions of the primary aquifer.
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A NATURAL GRADIENT TRANSPORT STUDY OF SELECTED
HERBICIDES
S.K. Widmer and R.F. Spalding, Water Center, University of Nebraska, Lincoln
An investigation of the behavior of commonly detected herbicides and herbicide degradates under
aquifer conditions was conducted in a shallow sand and gravel aquifer near Fremont, Nebraska.
Approximately 950 liters (250 gallons) of 3 ppb atrazine, 2 ppb alachlor, 10 ppb cyanazine, 10 ppb
metolachlor, 1 ppb butachlor, 3 ppb deethylatrazine (DEA), and 3 ppb deisopropylatrazine (DIA)
and a conservative tracer (sodium bromide) were injected into the aquifer in two experiments. The
plumes were monitored over several months. A system of multilevel samplers (MLS) was used to
delineate the solute plume. Fences of MLSs were arranged in arcs, such that eight arcs were
longitudinally located within the 7.3 meters (24 feet) monitored. The measured average rate of
ground-water flow at the study site was 15 cm day'1 (0.5 feet day'1). Samples were collected at
0.30-meter (1-foot) depth intervals.
A retardation factor (R) was determined for each pesticide by comparing its concentration profile to
that of the conservation tracer at a given distance. The triazines (atrazine and cyanazine, R=1.2)
were slightly less mobine than the acetanilides (alachlor and metolachlor, R=l. 1). DEA (R=l.l) was
more mobile than the atrazine, while DIA (R=1.3) was less mobile. Persistence of atrazine,
cyanazine, metolachlor, DEA, and DIA was verified by lack of loss of parent compounds and, in the
case of atrazine, static levels of the degradates. Alachlor and butachlor exhibited losses of
approximately 30 and 60%, respectively, while the conservative tracer showed a decrease of less
than 15%.
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HERBICIDE TRANSPORT AND DEGRADATION IN A PRISTINE
WATERSHED: THE FATE OF HERBICIDES DEPOSITED BY
PRECIPITATION
Aron E. Cromwell and E. Michael Thurman, U.S. Geological Survey, Lawrence, Kansas
Herbicides used in agricultural areas are being transported atmospherically and deposited by
precipitation onto pristine watersheds. The fate of these herbicides was studied at Isle Royale
National Park, an island park located in Lake Superior on the United States-Canadian border.
Rainfall, soil water, surface water, and soils were analyzed by combining solid-phase extraction
(SPE) with enzyme-linked immunosorbent assay (ELISA). This combination enabled the onsite
analysis of samples in which the concentrations of herbicides were as little as 5 ng/L. The SPE-
ELISA results were confirmed using gas chromatography/mass spectrometry (GC/MS) with
isotope dilution. Herbicides detected at Isle Royale included the triazine herbicides atrazine and
cyanazine, as well as two triazine metabolites, deethylatrazine and deisopropylatrazine. Maximum
atrazine and cyanazine concentrations in rainfall occurred in late spring, approaching or
exceeding the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) of 3.0
|ig/L for atrazine, and the health advisory (HA) of 1.0 ng/L for cyanazine. By mid-summer, rainfall
concentrations of the herbicides decreased to less than detection levels. Atrazine was detected in
small concentrations in water from all lakes that were sampled. Field data and soil-column and
lake-water degradation experiments indicate that atrazine degrades rapidly in soil environments,
but more slowly in aquatic environments. This slow degradation rate in water has important
implications for the quality of lakes in pristine areas receiving herbicide-contaminated rainfall
because the potential exists for the accumulation of herbicides to levels harmful to aquatic life.
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A COMPARISON OF ATRAZINE AND METOLACHLOR
BIOLOGICAL ASSESSMENT DATA TO CONCENTRATIONS
REPORTED IN PRECIPITATION MONITORING STUDIES
Philip A. Banks, MARATHON-Agricultural and Environmental Consulting, Inc., Las Graces,
New Mexico, and Dennis P. Tierney, Ciba Plant Protection, Greensboro, North Carolina
Several pesticides have recently been reported in precipitation, including the herbicides atrazine
and metolachlor. While data are limited on how these herbicides get into the atmosphere, it
appears that volatilization and particle erosion following application are the primary contributors.
Atrazine and metolachlor presence in precipitation is seasonal with the highest concentrations and
most detections occurring during and shortly after the peak application period in the spring. From
published reports, five for atrazine and three for metolachlor, atrazine was detected in
approximately 50% of the samples collected and metolachlor in approximately 20% of the samples.
For both herbicides, over 90% of the precipitation samples contained concentrations of less than 1
ppb (atrazine = 94% and metolachlor = 97%).
A biological risk assessment evaluated the significance of atrazine and metolachlor concentrations
in rainfall on various terrestrial and aquatic plants and animals. For atrazine, various algae
species were reported to have lowest observable response levels (LOEL) that ranged from 10 to 565
ppb in a variety of aquatic studies. Most terrestrial plants were more tolerant of atrazine, with
cucumber and cabbage having no observable effect levels (NOEL) of 12 and 6 ppb, respectively. In
general, aquatic and terrestrial plants were more tolerant of metolachlor than atrazine. Based
upon measured concentrations of each herbicide in rainfall, atrazine and metolachlor do not pose
an ecological risk.
Additionally, a human exposure assessment evaluated the potential health effects of atrazine and
metolachlor in rainfall relative to the Federal Safe Drinking Water Act and the Environmental
Protection Agency Health Advisory criteria. A dermal risk assessment is also provided. No adverse
health effects are expected due to drinking water or dermal exposure routes.
While historical data on atrazine and metolachlor presence in precipitation is limited to only five
published reports, two were in the atrazine and metolachlor high-use areas of the Midwest. Data
from these areas can be used to provide perspective on data from future studies.
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CHEMISTRY, DEGRADATION, AND TRANSPORT OF TRIAZINE
METABOLITES IN SURFACE WATER
E.M. Thunnan, U.S. Geological Survey, Lawrence, Kansas
Atrazine, one of the most extensively used herbicides in the midwestem United States, degrades in
soil to several important metabolites (principally deethylatrazine and deisopropylatrazine).
Atrazine field-dissipation studies show.that.only deethylatrazine persists in soil and is transported
to ground water through the unsaturated zone. In soil, deisopropylatrazine rapidly degrades
further to didealkylatrazine; consequently, deisopropylatrazine is found in.only trace amounts
relative to atrazine and deethylatrazine (approximately one-tenth the concentration or less).
Alternatively, deisopropylatrazine is more stable in surface water and is present at concentrations
equal to one-third the concentration of deethylatrazine. In areas where atrazine is the only parent
compound for these metabolites, the dichotomy in degradation rates makes the two atrazine
metabolites suitable indicators of surface- and ground-water interactions in the Corn Belt (a 12-
state region in the midwestern United States). The ratio of concentrations of each degradation
product to the parent compound may be used to distinguish ground-water flow paths, such as
streambank infiltration into ground water, ground-water contribution to streams during base flow,
and point-source contamination of an aquifer (such as a spill at a poorly constructed well). Other
herbicides that commonly occur with atrazine use also may be indicators of flow path. These
herbicides include cyanazine, propazine, and simazine. They degrade in soil to metabolites that
may be identical to atrazine metabolites and also may be indicators of surface- and ground-water
interactions in the Corn Belt.
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NONEQUILIBRIUM ADSORPTION AND DEGRADATION OF
ATRAZINE AND ALACHLOR IN SOIL
Gerard J. Kluitenberg, Leticia S. Sonon, and A. Paul Schwab, Department of Agronomy,
Kansas State University, Manhattan Kansas
___ ;^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^i
Atrazine and alachlor are chemically and biologically degraded during transport through soil.
Degradation of.atrazine produces daughter products such as hydroxyatrazine, deethylatrazine,
and deisopropylatrazine. Both herbicides..are also sorbed to soil particles during transport. This
research was conducted to provide insight into the mechanisms of airazine and alachlor
adsorption and degradation.
Laboratory leaching experiments were conducted by using 1.1 meter-long undisturbed soil
columns from four soils varying in texture, pH, and organic carbon content. Atrazine, alachlor, and
bromide were added at the soil surface at a rate similar to recommended rates. Solute application
was followed by steady-state water applications of 2.6 and 0.2 inches per day. respectively, for the
saturated and unsaturated flow conditions. Soil-water potential was set to approximately -0.3 bar
at the bottom of the unsaturated columns. Column effluent was collected at regular time intervals
and used to plot effluent breakthrough curves (BTC's).
Results from experiments with Pratt loamy fine sand will be presented. This soil was collected at
the Sandyland Experiment Field near St. John, Kansas, which overlies the Great Bend aquifer.
Mass recovery of atrazine at the conclusion of the experiments was 50 and 9%, respectively, for the
saturated and unsaturated leaching experiments. Greater degradation in the uns,aturated flow
experiement was mainly a result of the greater solute residence time within the soil. Under
saturated conditions, deisopropylatrazine and deethylatrazine were present in the column
effluents at or below detection limits; however, effluents collected from the unsaturated
experiments contained relatively high concentrations of the degradation products. Mass recovery
of alachlor was 10% for the saturated leaching experiemtns, and alachlor was not detected in the
effluent from the unsaturated flow experiments. Thus, degradation rates for alachlor were
significantly higher than atrazine degradation rates.
The results of batch adsorption experiments were used to calculate atrazine retardation factors of
7.7 and 12.5 for the saturated and unsaturated flow regimes, respectively. Atrazine BTC's would
be center-ed at 7.7 and 12.5 pore volumes if equilibrium adsorption prevailed during transport.
Measured centers of mass of the atrazine BTC's were located between 2 and 3 pore volumes. The
leftward shift of the BTCs indicates that nqnequilibrium adsorption significantly enhanced the
mobility of atrazine under both saturated and unsaturated flow conditions. Atrazine and its
degradation products ranked in order of decreasing mobility: deethylatrazine > atrazine >
deisopropylatrazine. Alachlor was found to be less mobile than atrazine, a result opposite from
that expected based on batch adsorption data. Thus, nonequilibrium adsorption also enhanced
alachlor movement but to a lesser extent. Modeling of the bromide BTC's with the advection-
dispersion equation yielded dispersivities of 1-2 centimeters. This indicates that nonequilibrium
due to the chemical kinetics of adsorption was more important than physical causes of
nonequilibrium.
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CYANAZINE METABOLITES IN SURFACE WATER: THE
TRANSPORT AND DEGRADATION OF LABILE HERBICIDES
M.T. Meyer and E.M. Thunnan, U.S. Geological Survey, Lawrence, Kansas
Gyanazine (2-chloro-4-(ethylamino)-6-(l-cyano-l-methylainino)-S-triazlne) is one of the five most
extensively used herbicides in the United States and is more labile than atrazine; however, there
are few studies of the fate and transport of cyanazine metabolites in surface water. A field-
dissipation study showed that cyanazine degrades to., a common atrazine metabolite,
deisopropylatrazine. Analysis of samples collected from several stream, sites during storm runoff
throughout the spring and early summer demonstrates that the ratio of deisopropylatrazine to
deethylatrazine (D2R) is an indicator of the quantity of cyanazine relative to atrazine. Cyanazine
was detected in 73%, cyanazine amide in 63%, deethylcyanazine in 36%, and deisopropylatrazine
in 52% of the samples collected during the first storm runoff after herbicide application in a
reconnaissance study of stream water from 150 sites in the midwestern United States. Except for
deisopropylatrazine, these compounds were detected in 5 to 30% of the samples collected in the
spring before planting and in the fall during low streamflow. In addition, both the storm-runoff
and herbicide reconnaissance studies show that the cyanazine amide-to-cyanazine ratio (CA/CR)
increased throughout the summer, indicating that the cyanazine amide is more stable than
cyanazine. Finally, the CA/CR may be an indicator of the length of time cyanazine resided in the
soil relative to its application in the spring.
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BIODEGRADATION OF PESTICIDES IN SUBSURFACE SAMPLES
FROM THREE MTOCONTINENT SITES
James L. Sinclair and Tony R. Lee, ManTech Environmental Technology, Inc.,
Robert S. Kerr Environmental Research Laboratory, Ada, Oklahoma
Little information is currently available concerning the biodegradability of pesticide contaminants
in the subsurface. Pesticide contamination of ground water .is. a particular problem in the
midcontinent region of the United States. To investigate pesticide biodegradatton in soil and
sediments from this region, subsurface drill core-samples were obtained from agricultural fields
which had received applications of pesticides near Iowa City, Iowa, Princeton, Minnesota, and
south-central Ohio. Cores were handled with aseptic technique to minimize microbial
contamination. Samples were taken from the surface to slightly below the water table from the
Iowa and Minnesota sites, and only from below the water table from the Iowa and Minnesota sites,
and only from below the water table at the Ohio site. Microcosms were made from the sediments
and spiked with 100 ppb 14C-ring labeled atrazine, alachlor, carbofuran or 2,4-D. Experiments
were run on the mineralization of the four pesticides and on the breakdown of atrazine and
formation of atrazine breakdown products.
Preliminary results indicate that the rate of mineralization of pesticides followed patterns based on
the type of pesticide, the nature of the soil or sediment used, and the different sites that sediments
were obtained from. Generally, 2,4-D was mineralized much more readily than the other pesticides
with 25 to 50% of the amount added being mineralized after 146 days of incubation. More 2,4-D
was mineralized in the saturated zone sediment microcosms from both the Iowa and Minnesota
sites than was mineralized in the surface soil or the unsaturated zone sediments. Usually about 10
to 15% of added carbofuran was mineralized in most sediments by day 146 of the experiment. The
greatest amount of carbofuran mineralization occurred in the Iowa surface soil, and slightly more
mineralisation occurred in the saturated zone than in the unsaturated zone sediments. For most
samples, about 5 to slightly more than 10% of added alachlor was mineralized by 146 days. The
largest amount of alachlor mineralization observed in this experiment, 21.8% of the added
alachlor, occurred in the saturated zone sediments from the Iowa site. More alachlor
mineralization occurred in the saturated zone sediments of the Iowa and Minnesota sites than in
the unsaturated zone sediments or even the surface soil. Atrazine was mineralized the least of any
of the four pesticides tested. About 4 to 15% of the amount of added atrazine was mineralized in
the different soils or sediments tested by 146 days of incubation. As with the other pesticides,
more atrazine mineralization occurred in the saturated zone sediments than in the unsaturated
zone sediments. Slightly more atrazine was mineralized in the surface soil than in the saturated
zone sediments of the Iowa site, but more atrazine was mineralized in the saturated zone
sediments than in the surface soil of the Minnesota site.
The distribution of 14C activity between water soluble, chloroform extractable, and bound residue
fractions varied with the chemical nature of the different pesticides. Generally, the largest amount
of 14C activity occurred in the soil bound fraction. Most sediment types yielded a mass balance of
C activity added to the
the total of all 14C activity from all fractions of 70% or more of the
microcosms.
14,
This work demonstrated that significant biodegradation of pesticides can occur in subsurface
sediments. It also showed that differences occur between subsurface sediment types and between
sites at different geographical locations.
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INCIDENCE OF CERTAIN CANCERS AND EXPOSURE TO
AGRICULTURAL HERBICIDES: MEASURES TO REDUCE
THE RISK
Robert J. Robel, Kansas State University Division of Biology, Manhattan, Kansas,
Frederick F. Holmes and Cathy D. Boysen, University of Kansas Medical Center,
Kansas City, Kansas
A case-control study in Kansas of soft-tissue sarcoma, Hodgkin's disease, and non-Hodgkin's
lymphoma found farm herbicide use associated with the incidence of non-Hodgkin's lymphoma,
but not soft-tissue sarcoma or Hodgkin's disease. Cases were newly diagnosed white males over 20
years of age with soft-tissue sarcoma, Hodgkin's disease, or non-Hodgkin's lymphoma, whereas
controls were white males from the general Kansas population matched to each case by age and
vital status. The incidence of non-Hodgkin's lymphoma increased significantly with days of
reported herbicide exposure per year and years of exposure. Male farmers exposed to herbicides
more than 20 days per year had a sixfold increase in the risk of non-Hodgkin's lymphoma
compared to nonfarmers. Farmers who used herbicides frequently and mixed or applied the
herbicides themselves had an eightfold increased risk compared to nonfarmers. Exposure data
were more abundant for phenoxyacetic acids (2,4-D, and 2,4,5-T), triazines (atrazine, cyanazine,
propazine, etc.), and uracils than for amides, benzoics, carbamates, and trifluralin. All herbicides
showed significant increased risk of non-Hodgkin's lymphoma except the uracils; however, the
assessments of risk were stronger for the phenoxyacetic acids and triazines because of the number
of cases involved. Farmers using protective equipment (rubber gloves, masks, etc.) had a lower risk
than those who did not.
A follow-up case-control study in eastern Nebraska looked at additional types of cancer (multiple
myeloma and chronic lymphocyte leukemia) and included women as well. Cases were white males
and females over 20 years old with various cancers, whereas control subjects were, residents of the
same area matched to the cases by age, sex, and vital statistics. As in the Kansas study, the
Nebraska study also showed increased risk of non-Hodgkin's lymphoma associated with 2,4-D
exposure for males aged 20 years or older. Men who mixed or applied 2,4-D had an additional
increased risk of non-Hodgkin's lymphoma, and that risk increased further with time spent in
contaminated clothing.
Results from these two studies provide justification for reducing human exposure to agricultural
herbicides and suggest possible ways of doing so.
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HAZARD ASSESSMENT OF ATRAZINE
Darrell D. Sumner, Charles B. Breckenridge, and James T. Stevens, Ciba Plant Protection,
Greensboro, North Carolina
Atrazine is a chloro-s-triazine herbicide that has been used for weed control in corn for over three
decades. It exerts herbicidal activity by inhibition of photosynthesis. It is not particularly toxic in
acute administration to animals (LD50 in rats about 3,000 mg/kg). Atrazine is not a reproductive
toxin, not a teratogen, not a mutagen (evaluated in over 50 tests), and probably not a carcinogenic
in humans. Evidence indicates that a carcinogenic response in female Sprague-Dawley rats is a
strain and species specific response. Therefore, low-level exposures do not constitute
unreasonable risk to humans.
Atrazine was not carcinogenic to three strains of mice in three different studies, not carcinogenic
in Fischer-344 rats, and not carcinogenic to male Sprague-Dawley rats. But, female Sprague-
Dawley rats fed atrazine in their diet showed an increased incidence and/or earlier onset of
mammary tumors, this was the only tumor response observed in these studies. This response was
manifest as an increase in the incidence of mammary tumors, which is highly spontaneous in this
strain of rat (incidence ranging to as high as 70% of aged females). Female Sprague-Dawley rats
have an estrogen-dependent hormone cycle that is progressively unstable with age. Increased
estrogen is thought to lead to the biological processes that produce tumors in these animals.
Ciba has conducted numerous special studies with atrazine. These studies have confirmed that
large doses atrazine (100 mg/kg) administered for short intervals (2 weeks) or lower feeding levels
(400 ppm or about 20 mg/kg/day) for a period of several months results in a prolongation of the
duration of estrous cycle in the female Sprague-Dawley rat. This response is accompanied by more
days in estrus (tissue under estrogen influence) as well as an elevation of circulatory estrogen
levels. This enhanced exposure to estrogen establishes an environment for appearance of these
already highly spontaneous mammary tumors in this strain of rat.
The mechanism by which atrazine affects the estrus cycle in Sprague-Dawley rats is thought to be
. .associated with its ability to interfere with estrogen binding and to exert an anti-estrogenic
response. This effect interferes with the normal control mechanisms for the estrus cycle. Receptor
binding studies, in vivo and in vitro, have revealed that the overwhelming concentrations of
triazine must be available at unoccupied estrogen receptor sites before the interferences can occur.
Binding .constants indicate that the concentration of atrazine required to interfere with the
estrogen receptor is 10;000 - 100,000 times more than that ofestrogen. Analysis of the mammary
tumor responses for the six studies conducted in female Sprague-Dawley rats suggests that
lifetime exposure to feeding levels in excess of 400 ppm would be required for tumor production. In
addition, the mechanism by which this highly varied strain and species-specific response is
produced has a receptor-mediated threshold; therefore; risk assessment for this tumor should be
conducted using the traditionally safety factor approach.
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ECOLOGICAL IMPACTS OF HERBICIDES--A REVIEW
Donald Huggins, Aquatic Ecotoxicology Program, Kansas Biological Survey,
Lawrence, Kansas
(Abstract not received in time for publication)
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WEED-CONTROL OPTIONS FOR REDUCING ATRAZINE IMPACT
David L. Regehr, Kansas State University, Manhattan, Kansas
Atrazine herbicide remains an important component of weed management in Kansas, where it is
applied to 71 and 74% of sorghum and corn acres, respectively. This widespread use reflects the
efficacy, favorable economics, and risk avoidance that com and sorghum producers seek for weed
management.
Vulnerability of atrazine to field loss via" surface-water runoff is a function of the .field's erosion
potential and plant-residue cover. In environmentally vulnerable areas, we recommend switching
from higher rates of soil-applied atrazine, to rates of 1 Ib/acre or less soil-applied, followed by
foliar-applied herbicides that contain about 0.5 Ib/acre atrazine. This atrazine use provides
superior control of tough broadleaf weeds like velvetleaf, cocklebur, and sunflower and has been
adopted by many corn and sorghum producers. It does require field scouting to determine weed
pressure and size, and additional application and herbicide costs.
Recent changes in the atrazine label prohibit application in certain "set-back" areas where field-
surface runoff enters streams, ponds, and tile-outlet terraces. Crop producers who want to
continue atrazine use near those areas are encouraged to establish vegetated buffer zones that
delay entry of field runoff into drainage ways. Or, producers may choose to rely more heavily on
alternatives to atrazine for weed control.
Dicamba and 2,4-D have limited potential as substitutes for atrazine because of their potential for
sorghum and corn injury. Several new herbicide alternatives to atrazine are being developed by the
agrichemical industry. These compounds appear to be environmentally benign but are based on a
mode of action that appears highly vulnerable to selection of resistant weed biotypes.
A key to reducing dependence on atrazine is integrated weed management where crop rotation,
highly competitive crops, and a vigorous weed-management effort, including tillage and herbicides,
combine to reduce weed pressure. Once weed pressure is reduced, low rates of foliar-applied
atrazine and band-applying herbicides at planting and cultivation become more attractive options.
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IMPACT OF CONSERVATION TILLAGE SYSTEMS ON
AGRICULTURAL RUNOFF
D.W. Rushing, Monsanto Agricultural Company, Des Moines, Iowa
During the past several years, ground water has received most of the attention when the issue of
water quality has been discussed. However, surface water is actually far more vulnerable and often
more contaminated. More than half of the .U.S. population drinks surface water, including many
larger cities. Wells contaminated by herbicides have often been traced to point, sources at mixing
and disposal sites or from accidental spills. But contamination of .surface, water is largely a
nonpoint-source problem. As soil erodes and water runs off fields, herbicides are carried with it,
either adsorbed to the soil particles or dissolved in the water. Some commonly used soil-applied
herbicides runoff with water rather than attaching to soil sediment. Reducing soil erosion alone
will not entirely solve the problem of surface-water contamination. Most soil conservation practices
slow or reduce water runoff, explaining why herbicide detections are reduced by practices such as
conservation tillage, filter strips, and waterways.
Midwestern university results Indicate conservation tillage significantly reduces herbicide runoff.
Long-term no-tillage sometimes totally eliminated water and herbicide runoff by allowing greater
water infiltration. Averaging all natural rainfall studies, no-till reduced herbicide runoff by 70%.
Ridge till and chisel plowing also reduced runoff. Reducing soil erosion will often protect surface-
water supplies from herbicide runoff. A 15-foot wide grass filter strip reduced atrazine runoff from
a conventionally tilled field by 78% compared to a tilled field without a filter strip. Other best-
management practices currently in place should also aid in protecting water supplies. These
include "no spray zones" around points of entry into water bodies and tile inlet drains, limits on
early preplant applications, application restrictions near lakes and reservoirs, and herbicide rate
reductions.
There are a number of Federal, State, and industry supported programs that encourage farmer
adoption of best-management practices. One such program is Monsanto's Operation Green Stripe,
which, along with local FFA chapters, provides incentives for farmers to establish vegetative filter
strips along streams, rivers, lakes, and around sinkholes. The project will involve over 500 farmers
in seven states in 1993.
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PESTICIDE INCORPORATION AND TILLAGE AFFECTS
ATRAZINE AND ALACHLOR LOSSES
James Steichen, Philip Barnes, Hirozumi Watanabe, Kansas State University, Manhattan,
Kansas, Elbert Dickey, David Shelton, Paul Jasa, and Nathan Watermeier, University of
Nebraska-Lincoln, Lincoln, Nebraska
The effect of tillage practice and the method of chemical application on atrazine and alachlor losses
through runoff and erosion were evaluated on five treatmentsno-till and pre-emergent (N.P), disk
and pre-emergent (D.P), plow and pre-emergent (P.P), disk and pre-plant incorporated (D.I), and
plow and pre-plant incorporated (P.I) treatments. A rainfall simulator was used to create 63.5
mmhr'1 for 15 minutes. Rainfall simulation occurred 24-36 hours after chemical application. The
concentration of herbicides in the water decreased with time. No-till treatments had the highest
concentration, and disk treatments were higher than plow treatments. The pre-emergent
treatment showed higher concentration than incorporated. Total herbicide loss of atrazine ranged
from 0.08 kg ha'1 (5.2% of applied mass for N.P treatment) to 0.007 kg ha'1 (0.4% of applied mass
for P.I treatment) and that of alachlor ranged from 0.14 kg ha"1 (6.1% of applied mass for N.P
treatment) to 0.01 kg ha'1 (0.4% of applied mass for D.I treatment). No-till, pre-emergent
treatments had the highest loss. For no-till, 98% of atrazine loss and 97% of alachlor loss occurred
in the runoff water. Reducing both runoff and erosion contributes to reducing herbicide losses.
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IMPACT OF CONSERVATION PRACTICES ON AGRICULTURAL
NONPOINT CONTAMINATION
Philip L. Barnes, Kansas State University, Topeka, Kansas Mike Pope, and Andy Foster,
U.S. Geological Survey, Lawrence, Kansas
The U.S. Department of Agriculture has developed conservation practices to reduce soil loss to
surface runpff. The practices include terracing, crop-residue management, and contour fanning.
During the development and testing of terrace designs, the water that was caught by the terrace
was moved off the field by grassed waterways. It was felt that .if erosion could be reduced that
nutrient and pesticide losses would also be reduced. Recent government programs have allowed
the grass waterways used to channel water away from terraces to be replaced by tile outlets. These
tile outlets hold the water in the terrace channel long enough to deposit sediments and then the
water is rapidly transported off the field through the tile.
A majority of the herbicides used today are relatively soluble in water. When rainfall causes
surface runoff from fields, it is carrying both sediments and herbicides. In the past, terraces
drained into grass waterways that filtered the herbicides in the runoff water. Research would
indicate that the tile-outlet terrace system may be a new source of nonpoint contamination.
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FEDERAL, STATE, AND LOCAL COOPERATION TO IMPROVE
SURFACE-WATER AND GROUND-WATER QUALITY: A CASE
STUDY FROM RECHARGE LAKE IN YORK COUNTY, NEBRASKA
Robert A. Dunlevy, U.S. Environmental Protection Agency,
Kansas City, Kansas
Several Federal, State, and substate water-resource agencies are working together to reduce the
impact of pesticide residue on ground-water quality at the York Groundwater Recharge
Demonstration Project near York, Nebraska. This work is being .performed while continuing to
demonstrate the feasibility of recharging the ground water. The York Project is one of the Bureau of
Reclamation's original 21 projects in the High Plains States Groundwater Recharge Demonstration
Program.
Recharge Lake, a reservoir constructed to provided a supply of active and passive recharge water,
is surrounded by ground-water monitoring wells. The monitoring wells are used to evaluate the
success of the ground-water recharge efforts through the measurement of the ground-water
elevations and to sample the ground-water quality.
Sampling of the lake water following 1991 and 1992 spring storm-runoff events indicated several
pesticides, particularly atrazine, exceeded their Maximum Contaminant Level (MCL) in the
reservoir. Samples from the ground-water monitoring wells also indicated higher pesticides levels,
several above their MCL. Currently, there are no recharge activities at the project; any pesticides
entering the ground water is from the seepage through the lake bottom.
The concern is that the lake is recharging the ground water with pesticides, and this process may
be occurring in other impoundments throughout the Midwest and could affect the beneficial uses
of ground water. Federal, State, and substate agencies along with private industry are combining
their efforts and resources to study the surface and subsurface hydrodynamics. The information
gathered will be used to develop a plan to reduce the pesticides in the surface runoff and
subsequently the ground water.
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MANAGEMENT OF HERBICIDES IN THE DELAWARE
RIVER BASIN
Jane Niehues, Steering Committee for the Non Point Pollution Plan for the Delaware River
Basin, Goff, Kansas
Atrazine concentrations in Perry Lake, a reservoir within the Delaware River drainage basin, have
become a concern to farmers, water suppliers, and regulators. As a result, a Pesticide Management
Area was formed and a Non Point Source Pollution Plan has been developed. The committee that
developed the plan consists of one member of each Conservation District Board from Nemaha,
Brown, Atchison, Jefferson, and Jackson Counties, and a representative from the Kansas Rural
Center. The effort is being coordinated by the Glacial Hills RC&D.
This presentation will describe the atrazine problem within the Delaware Drainage Area, the
formation of the Pesticide Management Area, and discuss the Non Point Source Pollution Plan. The
discussion will include proposed methods to decrease atrazine runoff, such as: terraces,
waterways, contouring farming, conservation tillage, integrated crop management, watershed
dams, and application methods. A monitoring program is now in place and development of a
proposed geographic information system also will be discussed.
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WEST LAKE WATER QUALITY PROJECT
Alan Teel, Iowa State University of Science and Technology, Osceola, Iowa
The West Lake Water Quality Protection Project began in November of 1990 and will continue until
the fall of 1995. Planning for the project started in 1988. Funding for the project is through the
U.S. Environmental Protection Agency section 319 funding. Cooperating agencies are the Iowa
Department of Agriculture and Land Stewardship, Division of Soil Conservation; the U.S.
Environmental Protection Agency; the Clark County Soil and Water Conservation District; and the
Iowa State University Extension Service.
The West Lake Water Quality Project's primary objective is to preserve, protect, and improve the
West Lake reservoir for use as a municipal, industrial, and rural water supply, and as a fish,
wildlife, and recreational resource. Additionally, we want to achieve a level of project participation
and practice adoption that will result in significant water-quality protection within the 5-year
project period and to demonstrate the technical and economic feasibility and the effectiveness of
the resource management practices being used as part of this project in hope that these practices
will be adopted as permanent practices in the cooperator's farming operation.
The project will market pre-packaged basic conservation systems that reduce soil loss to T."
Financial incentives paid up-front to producers who enter into a 5-year compliance agreement will
help to secure producer participation. An integrated crop-management program will be provided
for each cooperating producer. Additionally, an informational program will be put in place to
include field days and educational meetings.
Eleven hundred and thirty-six (1,136) acres are now under contract agreement, and an additional
575 acres have been designated as "volunteer compliance" acres. These volunteer compliance
acres are being managed in compliance with project guidelines but are not under an agreement
and are not receiving any payments. Thirteen educational classes have been conducted, 1 field
day, 7 news articles, 1 television interview, and 15 radio programs have been generated via this
project.
Providing "up front" funding for producers appears to be a viable way to attract the participation of
producers in the West Lake watershed in soil conserving practices. The inclusion of Integrated
Crop Management practices has helped in facilitating the soil conserving practices. Active
ififorniatibnal and educational programs have increased the public's awareness of the project and
have helped to support producers in the decision-making process.
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INFLUENCE OF MANAGEMENT PRACTICES ON WATER QUALITY
IN WALNUT CREEK WATERSHED
J.L. Hatfield1, R.C. Buchmiller2, P.J. Soenksen2, and D.B. Jaynes1
1USDA - Agricultural Research Service, National Soil Tilth Laboratory, Ames, Iowa.
2U.S. Geological Survey, Iowa City, Iowa.
Influence of farming practices on both surface- and ground-water quality is difficult to quantify on
a field and watershed scale; however, it is apparent that a linkage exists between different fanning
practices and their potential effect on water quality. To evaluate the impact of different farming
practices, a study was designed in a large agricultural watershed to investigate the seasonal and
positional variations in water quality.
Walnut Creek watershed is a 5,400-hectare watershed located south of Ames, Iowa, on the Des
Moines landform region. This region is characterized by a relatively level surface with poorly-
defined surface-runoff features and an extensive number of prairie potholes. These potholes are
poorly drained, and to remove the water from the soil profile, tile drain lines are placed throughout
the watershed in a network. These drain lines remove water from, the fields and route it to the
stream. Walnut Creek as a stream empties into the Skunk River. There are a wide range of soils
within the watershed ranging from moderately well-drained to poorly drained soils and a
topography that varies from nearly level, e.g., less than 2% slope, to 5-7% slope in the lower
reaches of the watershed.
The watershed.is extensively farmed as a corn-soybean rotation system with field sizes that range
from 20 to 150 hectares. Nearly 90% of the land area within the watershed is cultivated as a row
crop. The inputs of chemical fertilizers and herbicides within the watershed are typical of the Corn
Belt.
In 1991 a study began within the watershed to evaluate the current farming practices on water
quality. Three stream-monitoring stations where installed to measure the stream discharge, water
quality, and sediment load. Eight tile-monitoring locations were installed to measure both the
discharge and the water quality. Surface-runoff flumes were installed in three fields. Over 40 well
nests were placed around individual fields and subbasins to measure the quality of the ground
water .at depths from 2.5 to. 15 meters. The agricultural chemicals being measured within the
watershed include: atrazine, alachlor. cyanazine. metribuzin, metolachlor, and nitrate-nitrogen.
These analytes are measured in stream, tile, well samples, and rainfall, as well as soil samples
collected from individual fields.
There is a large seasonal variation in the concentrations of herbicides detected in the stream and
tile drainage. This variation is related to the occurrence of surface runoff from the edge of fields or
entry of surface water into the tile inlets. Base-flow concentrations in the tile and stream for the
herbicides did not exceed the EPA limits. Nitrate-nitrogen values, however, ranged from 10 to 20
ppm throughout the year in the tile and surface water but did not exceed 5 ppm at well depths
below 2.5 m. The seasonal variation in the nitrate-nitrogen concentrations is related to the rate of
mineralization within these organically rich soils and has not shown an effect of the fertilizer
application times. The different farming practices that are being examined will provide an insight
into the loadings that are resulting from current practices and will be used to determine the extent
to which improvements in water quality can be achieved.
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UTILIZING FERTILIZER AND CHEMICAL DEALERS
TO MANAGE PESTICIDES
Duane Sand, Director, Long Range Planning and Research, Iowa Natural Heritage
Foundation
(Abstract not received in time for publication)
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Posters on Display during Tuesday Social Hour
Coordinator: Hyde Jacobs, Kansas State University
Water-Quality Characteristics of Stormwater Runoff in Davenport, Iowa
Bryan Schaap and Keith J. Lucey, U.S. Geological Survey
Isocratic Separation ofAlachlor Ethane Sutfonic Acid, Alachlor Oxacetic Acid, and
Hydroxatrazine by Reversed-Phase Liquid. Chmmatography
Michael L. Pomes and E.M. Thurman, U.S. Geological Survey
Chromatographic Applications of Solid-Phase Extraction in Developing
Immunoassay Methods for Herbicides and their Metabolites: An Example for
Alachlor and Atachlor-EthanesuJfonic Acid
Diana S. Aga and E.M. Thurman, U.S. Geological Survey
Use of a Geographic Information System Procedure to Estimate Atrazine Impact
John Hickman, Ray E. McDonald, H.L. Seyler, and Michel D. Ransom, Kansas
State University
Estimating Pollutant Soil Ratings
John Hickman, P.R. Finnell, and R.L. Schlepp, Kansas State University and
U.S. Soil Conservation Service
Reconnaissance Data for Herbicides and their Metabolites in Surface Water of the
Midwestern United States: Immunoassay and Gas Chjomatography/Mass
Spectrbmetry
Elisabeth A. Scribner, E.M. Thurman, and Donald A. Goolsby, U.S. Geological
Survey
Atrazine Management to Meet Water-Quality Criteria
David L. Regehr, Dallas E. Peterson, and John S. Hickman, Kansas State
University . .- .
Effects of Pore-Size Distribution and Saturation Cycles on Atrazine and Bromide
Transport through Soil
E.A. Smith, P.J. Shea, W.L. Powers, and D.R. Tupy, University of Nebraska-
Lincoln
Selected Herbicides in Bottom Sediments of Water-Supply Reservoirs in Iowa
Stephen J. Kalkhoff, U.S. Geological Survey; Jack Kennedy, University of Iowa
Hygenic Laboratory; Ubbo Agena, Iowa Dept. of Natural Resources; George
Breuer, University of Iowa Hygenic Laboratory
The Comprehensive Environmental Economic Policy Evaluation System: An
Application to Atrazine and Water Quality
Aziz Bouzaher, Center for Agricultural and Rural Development and Andrew
Manale, U.S. Environmental Protection Agency
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WATER-QUALITY CHARACTERISTICS OF STORMWATER
RUNOFF IN DAVENPORT, IOWA
Bryan D. Schaap and Keith J. Lucey, U.S. Geological Survey, Iowa City, Iowa
To comply .with U.S. Environmental Protection Agency (EPA) regulations to obtain a permit for
stormwater discharges, the City of Davenport, Iowa, conducted an urban stormwater-runoff study
in cooperation with the U.S. Geological Survey during the summer and fall of 1992. Five
monitoring sites were selected to characterize the water quality of storm runoff from the following
land-use types: agricultural, residential, commercial, industrial, and undeveloped areas. Three
sets of stormwater-runoff samples were collected at each of the open-channel monitoring sites.
Stormwater samples for a particular site were collected at least 30 days apart and after a 72-hour
period had elapsed with less than 0.1 inch of rain. Rainfall totals for the events sampled varied
from 0.09 to 0.48 inch from the beginning of the storm to the time the last sample was collected.
Each set of samples consisted of both grab and composite samples. Grab samples were collected
within the, first hour of the runoff event and were analyzed for oil and grease, cyanide, bacteria,
total phenols, and volatile organic carbons. Discrete samples, collected about every 15 minutes for
the first 3 hours of the event, were used to produce flow-weighted composites that were analyzed
for many constituents, including biochemical oxygen demand, chemical oxygen demand, total
organic carbon, major ions, metals, acid/base-neutral organics, polyaromatic hydrocarbons,
nutrients, and organo-chlorine pesticides.
Total nitrogen and nitrate concentrations were greatest at the agricultural site. Metal
concentrations (Ni, Pb, Zn) were greatest at. the industrial site. Pesticide concentrations were less
than the minimum reporting levels for single samples collected at the agricultural and residential
sites and for two samples collected at the industrial site.
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ISOCRATIC SEPARATION OF ALACHLOR ETHANE SULFONIC
ACID, ALACHLOR OXACETIC ACID, AND HYDROXYATRAZINE
BY REVERSED-PHASE LIQUID CHROMATOGRAPHY
MX. Pomes, D.F. Holub, and E.M. Thurman, U.S. Geological Survey, Lawrence, Kansas
The polar nature of two alachlor metabolites, alachlor ethane sulfonic acid and alachlor oxacetic
acid, makes their detection by gas chrbmatography/mass spectrometry impossible without
derivatization. Enzyme-linked irnmunosorbent-assay techniques cannot distinguish alachlor
metabolites from alachlor; thus, reversed-phase high-pressure liquid chromatography with
photodiod array detection is required for the separation and spectral detection of these analytes.
Use of an isocratic methanol/10 mM (millirnolar) Na2HPO4 buffer mixture as the mobile phase
with reversed-phase (C18) high-pressure liquid chromatography allows for the separation and
detection of alachlor ethane sulfonic acid, alachlor oxoacetic acid, and hydroxyatrazine at
concentrations greater to or equal to 0.1 (ig/L using 100-milliliter water samples. The buffer in the
methanol mixture provides cations that tori pair with the alachlor metabolite anions to decrease
polarity and promote nonpolar interactions between the analytes and the reversed-phase column.
Enhanced chromatographic resolution results from injecting samples in a matrix that contains
proportionally less methanol than the mobile phase. The disparity between methanol contents of
the sample matrix and mobile phase focuses the analytes at the head of the chromatographic
column to produce sharper peaks because the analytes are less soluble in the sample matrix than
in the mobile phase. Results by reversed-phase high-pressure liquid chromatography show that
alachlor ethane sulfonic acid is frequently found in surface water, with lesser concentrations of
alachlor oxoacetic acid and hydroxatrazine.
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CHROMATOGRAPHIC APPLICATIONS OF SOLID-PHASE
EXTRACTION IN DEVELOPING IMMUNOASSAY METHODS FOR
HERBICIDES AND THEIR METABOLITES: AN EXAMPLE FOR
ALACHLOR AND ALACHLOR-ETHANESULFONIC ACID
D.S. Aga and E.M. Thurman, U.S. Geological Survey, Lawrence, Kansas
The resolving property of solid-phase extraction (SPE) and the sensitivity of enzyme-linked
immunosorbent assay (ELISA) were combined to produce a highly selective and ultra-sensitive
analytical technique for the analysis of ultra-trace levels of the herbicide alachlor arid its
metabolite, alachlor-ethane sulfonic acid (ESA). The high cross reactivity of the anti-alachlor
antibody towards ESA was used as a positive feature, rather than a drawback, for developing a
method for both the parent compound and the metabolite. Alachlor and ESA were separated using
SPE by sequential elution with ethyl acetate followed by methanol. The ethyl acetate effectively
elutes the alachlor while leaving the ESA adsorbed in the C18 resin. The succeeding elution with
the more polar solvent methanol removes more than 95% of the ESA from the resin. The extracts
were evaporated to dryness and re-dissolved in water/methanol (80/20) for analysis by ELISA. The
method has a detection limit of 0.01 ng/L for alachlor and 0.05 \ig/L for alachlor-ESA, with a
precision of + 10%. Results obtained from the analysis of surface- and ground-water samples were
confirmed by high-performance liquid chromatography with photodiode array detection and gas
chromatography/mass spectrometry, and results agreed to within + 10%.
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USE OF GEOGRAPHIC INFORMATION SYSTEM PROCEDURE TO
ESTIMATE ATRAZINE IMPACT
John S. Hickman, Ray E. McDonald, H.L. Seyler, and Michel D. Ransom, Kansas State
University, Manhattan, Kansas
Kansas is the first State in the Nation to form a Pesticide Management Area to address elevated
pesticide concentrations in surface waters. A Pesticide Management Area was formed for atrazine
in the Delaware River watershed in northeast Kansas.. Atrazine management practices,
conservation practices, arid .riparian management are considered as pollutionrcontrol practices to
reduce atrazine runoff. A geographical information system procedure is being used to evaluate
data for atrazine impact analysis in the Delaware River watershed. Important data layers include
soils, land cover, and hydrology.
The study area consists of three subwatersheds within the Delaware River watershed
{Grasshopper Creek, Coal Creek, and Cedar Creek). Three digitized data layers and accompanying
data bases (soils, land cover, and hydrology) were combined using ARC/INFO. The soils data layer
is being digitized at the Kansas State University GISSAL (GIS Spatial Analysis Laboratory) at a
1:24,000 scale. Soil digitization is part of a separate project to complete digitization of soils in
Kansas. Atrazine loss potential was estimated using hydro-logic groups, with hydrologic group D
soils having the most severe solution-loss potential and hydrologic group A soils the least.
Hydrologic group has proven to be a good indicator of pesticide solution-loss potential. Highly
erodible land status was also determined for each soil mapping unit. It should be noted that
mapping highly erodible land status by soil mapping units is not representative since actual status
is determined on a field basis.
The land-cover data layer was digitized at the Kansas Applied Remote Sensing laboratory at the
University of Kansas. Land cover was determined from 30-meter LANDSAT images taken in 1988.
Five classes of land-cover data were considered: cropland, grassland, woodland, water, and other.
The hydrology data layer was traced from 7.5-minute U.S. Geological Survey quadrangles.
Information was scanned and imported into ARC/INFO. Twenty and four (24)-meter buffers were
created around hydrology features.
The geographic information system procedure proved valuable in estimating potential impact of
atrazine loss to surface water. There were some discrepancies between the soil, hydrology, and
land-cover data, especially relative to water features. Also, the digital land-cover data contained
some polygons that had too many arcs for PC ARC/INFO version 34d. This information had to be
read and clipped using a workstation version of ARC/INFO.
Digitized soil information enabled rapid display of atrazine loss potential. Addition of digitized
land-cover information identified cropland, the land cover most likely to receive applications of
atrazine. Soil credibility status provided information on practices that can be used to reduce
atrazine runoff. Highly erodible soils have conservation requirements needed to meet the
conservation compliance provision of the 1985 Farm Bill. Such soils rely on structural and residue
management practices to meet soil-erosion goals. Such practices also help reduce atrazine runoff
losses. There was some non-highly erodible cropland identified with a severe atrazine runoff loss
potential. Non-highly erodible soils have additional tillage and incorporation options to reduce
atrazine runoff losses. Buffering hydrologic features in a GIS format provided information on
atrazine loss potential in riparian areas. Ground truth has not been completed to determine
whether 30-meter LANDSAT images accurately reflect land cover in the riparian area.
This project was funded in part from a grant from the National Agricultural Pesticide Impact
Assessment Program (NAPIAP).
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ESTIMATING POLLUTANT SOIL RATINGS
John S. Hickman, Paul R. Finnell, and Richard L. Schlepp, Kansas State University and
U.S. Soil Conservation Service, Manhattan, Kansas
Estimating soil potential for pesticide loss is an important consideration in planning for nonpoint-
source pollution control. Several screening procedures have been developed by the USDA to group
soils into severe, moderate, or slight utensils for pesticide runoff and leaching. The objective of this
study was to evaluate soil-screening procedures for solution, adsorbed, and leaching loss of
pesticide using the GLEAMS model. .. . . ..
Pesticide loss was simulated for soil mapping units from five Kansas counties using the GLEAMS
model (version 1.8.55). The counties represent vastly different geographic and climatic regions.
Thirty-year simulations were completed for continuous grain sorghum under dryland and irrigated
conditions. The pesticides atrazine, glyphosate, and aldicarb were simulated to represent solution,
adsorbed, and leaching loss, respectively. Evaluation of screening procedures was completed by
comparing^to simulated pesticide loss values.
GLEAMS predicts runoff based on a curve-number approach, which Is significantly affected by
hydrologic soil group (HSG) but not by slope. An improved soil-screening procedure was developed
that uses HSG as an initial variable to group soils. Slight-rated soils are HSG A, moderate-rated
soils are HSG B, and severe-rated soils are HSG C and D. Differences in climate were considered
by lowering HSG C soils (dryland only) one class if in a Ustic moisture regime. Further
modifications for flooding were added to reflect soils in an occasional or frequent flooding class.
None of the existing screening procedures did a good job of grouping soils for adsorbed loss. These
procedures did not account for important factors such as slope, slope length, soil credibility, and
climate. The improved soil-screening procedure uses the RKLS factor in Universe Soil Loss
Equation to group soils for adsorbed loss. Values of RKLS of 20 and 40 were chosen to group soils
into rating classes. All soils with a RKLS > 40 are considered highly erodible due to sheet and rill
erosion for the conservation compliance provision of the 1985 Farm Bill and are rated severe for
pesticide absorbed loss. Soils with an RKLS factor between 20 and 40 are rated moderate, while
those below 20 are rated slight. As in solution-loss ratings, further modifications for flooding were
considered.
Existing pesticicie-leaching screening procedures use HSG, surface-horizon depth, and surface
organic-matter content to initially categorize soils for leaching loss. Further modifications are
made for climate, slope, water table, depth to highly permeable material, and bedrock. The
GLEAMS model did not predict lower amounts of percolation or leaching on highly sloping soils.
An improved soil-screening procedure was developed that did not consider slope and only
considered apparent water tables not perched water tables. Type of water table and permeability of
bedrock are important variables and need careful evaluation in the soil data base.
This project was funded in part from grants received from the U.S. Environmental Protection
Agency, the Kansas Department of Health and Environment, and the State Conservation
Commission.
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RECONNAISSANCE DATA FOR HERBICIDES AND THEIR
METABOLITES IN SURFACE WATER OF THE MIDWESTERN
UNITED STATES: IMMUNOASSAY AND GAS
CHROMATOGRAPHY/MASS SPECTROMETRY
Elisabeth A. Scribner, E. Michael Thunnan, and Donald A. Goolsby, U.S. Geological
Survey, Lawrence, Kansas, and Lakewood, Colorado
Chemical data were collected during 1989-90 for an assessment of. preemergent herbicides and
their metabolites from 147 rivers and streams located in 10 states in the midwestem United
States. All water samples were collected using depth-integrating techniques at three to five
locations across each stream. Sites were sampled three times in 1989before application of
herbicides, during the first runoff event after application of herbicides, and in the fall during a
base-flow period when most of the streamflow was derived from ground water. Fifty sites were
resampled with a stratified random procedure for both pre- and post-application in 1990 to verify
the 1989 results. Samples were analyzed by enzyme-linked immunosorbent assay (ELISA) and
confirmed by gas chromatography/mass spectrometry (GC/MS). The results proved useful in
studying herbicide transport, comparing the spatial distribution of the concentrations of 10
herbicides and 2 metabolites (deethylatrazine and deisopropylatrazine) in streams and rivers after
their application on a regional scale, examination of the persistence of herbicides and their
metabolites in surface water, and usefulness of atrazine metabolites as indicators of surface- and
ground-water interaction.
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ATRAZINE MANAGEMENT TO MEET WATER-QUALITY CRITERIA
David L. Regehr, Dallas E. Peterson, and John S. Hickman, Kansas State University,
Manhattan, Kansas
Atrazine is the pesticide most frequently exceeding the Environmental Protection Agency's
proposed Maximum Contaminant Level (MCL) in Kansas surface waters. Northeast Kansas, a
region that .depends heavily on surface waters for public water supplies, is the most severely
impacted. Atrazine concentrations above the 3 ppm MCL are common in many streams during the
summer months and may occur year around below major reservoirs.
Pesticides in surface-water runoff are partitioned into either the adsorbed (sediment) or solution
(water) phase, depending on their solubility and partition coefficient. About 90% of atrazine lost in
surface runoff is in the solution phase. Atrazine loss is highest in the first runoff event after
application, with the first runoff having the highest atrazine concentrations. Most of the atrazine
lost in runoff comes from the "mixing zone," the top half inch of soil.
Thirty years of northeast Kansas weather data were used to predict atrazine losses associated with
different application practices. Atrazine applied in early April is less than half as susceptible to
runoff loss as that applied in late May and June, due to differences in rainfall amounts and
intensities. Soil incorporation of atrazine decreases runoff losses by about 65%, compared to
surface application. Reducing atrazine rates through banding or foliar applications decreases
runoff losses dramatically. These factors can be used to formulate atrazine-use programs with the
aim of reducing atrazine concentrations in surface waters by 50%.
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EFFECTS OF PORE-SIZE DISTRIBUTION AND SATURATION
CYCLES ON ATRAZINE AND BROMIDE TRANSPORT
THROUGH SOIL
EJL Smith, P. J. Shea, W.L. Powers, and D.R. Tupy, University of Nebraska-Lincoln,
Lincoln, Nebraska
Recent research in Nebraska revealed a relationship between soil pore-size distribution (PSD),
reflected in a PSD index, and atrazine transport through surface soil. Atrazine and bromide
transport through a Crete silt loam from a corn producing area was related .to PSD and bulk
density. Undisturbed soil cores were collected to a depth of 7 cm from wheel traffic and non-wheel
traffic locations and within rows in a conventionally tilled continuous com field. Atrazine and
bromide were applied at 4.9 kg a.i. ha"1 (approximately twice the field rate) and 66 kg ha"1,
respectively, to each core and allowed to equilibrate 72 h. Leachate was collected at increasing
water potentials between 10 and 1,000 cm during multiple desaturation cycles. The Brooks and
Corey equation was used to calculate PSD from relative soil-water content and matric tension. A
significant positive association between total bromide eluted and PSD index and a significant
negative association between total atrazine eluted and PSD index suggested more bromide
transport and less atrazine transport in soils with a larger fraction of larger sized pores.
Observations indicated that pore-size distribution may be a more sensitive indicator of atrazine
transport than bulk density. Relatively equal amounts of bromide eluted in the first three
desaturations, while decreasing amounts of atrazine eluted after each desaturation. First-order
degradation can explain the atrazine reduction after desaturation two, while the reduction in
atrazine eluted during the third desaturation may be due, in part, to other physical and chemical
processes.
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Selected Herbicides in Bottom Sediments and Water
of Water-Supply Lakes in Iowa
1S.J. Kalkhoff, 2J. Kennedy, ^V. Agena and 2G. Breuer
1 U.S. Geological Survey, Iowa City, Iowa
2 University of Iowa Hygenic Laboratory, Des Moines, Iowa
3 Iowa Department of Natural Resources, Des Moies, Iowa
A cooperative study to investigate the occurrence of several common herbicides in 15 water-supply
lakes in Iowa was conducted by the Iowa Department of Natural Resources, the University of Iowa
Hygienic Laboratory, and the U.S. Geological Survey. The study was conducted in February and
March 1993 when the lakes were ice covered to ensure minimal input of sediment from runoff and
minimal sediment resuspension due to wave action. The lakes sampled ranged from 12 to about
5,700 acres in size, with drainage areas of about 500 to 15,000 acres. Land use within the
watersheds is primarily row-crop agriculture. Samples were collected from 12 lakes in the
southern Iowa and three natural lakes in northwestern Iowa and analyzed for alachlor, atrazine,
butylate, cyanazine, metolachlor, metribuzin, and trifluralin. Bottom-sediment and water samples
were collected at a site in shallow water near the primary inflow and at a site in the deepest part of
the lake; on two lakes, samples were collected only from the inflow site.
Three of the seven herbicides were detected (detection limit varied from 3 to 5 ng/kg) in sediment
samples. Atrazine was detected in the sediment samples from eight lakes, cyanazine in two lakes,
and alachlor in two lakes. Atrazine was detected in 46% of all sediment samples, cyanazine in
14%, and alachlor in 14%. Metolachlor, metribuzin, butylate, and trifluralin were not detected.
Atrazine concentrations ranged from less than the detection limit to 16 ng/kg; cyanazine
concentrations ranged from less than the detection limit to 14 ng/kg; and alachlor concentrations
ranged from less than the detection limit to 90 |ig/kg. Atrazine concentrations in sediment
samples from the deep sites were not significantly different (p>0.05) at the 95% confidence level
than in sediment samples from the shallow sites, even though atrazine was detected more
frequently in sediment at the deep sites (62%) than at the shallow sites (33%).
Four of the seven herbicides were detected (detection limit 0.1 |ig/L) in water samples. Atrazine
was detected in the water samples from 14 lakes, cyanazine in 8 lakes, metolachlor in 3 lakes, and
trifluralin in 1 lake. Atrazine was detected in 89% of all water samples, cyanazine in 50%,
metolachlor in 14%, and trifluralin in 4%. Alachlor, metribuzin, and butylate were not detected.
The atrazine concentrations in water ranged from less than the detection limit to 2.3 pg/L;
cyanazine concentrations ranged from less than the detection limit to 1.2 fig/L; and metolachlor
.concentrations ranged from less than the detection limit to 0.19 |ig/L. Atrazine and cyanazine
concentrations in the water were not significantly different (p>.0.05) between the shallow and deep
sampling sites.
Atrazine concentrations in the bottom sediment were determined to have a weak but significant
relation (r^O.S?; p=0.0005) to the atrazine concentrations in the overlying water. This relation
could not be tested for the remaining herbicides studied because of the lack of detectable
concentrations in the sediment, water, or both.
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THE COMPREHENSIVE ENVIRONMENTAL ECONOMIC POLICY
EVALUATION SYSTEM: AN APPLICATION TO ATRAZINE AND
WATER QUALITY
Aziz Bouzaher, Center for Agricultural Rural Development, Ames, Iowa, and Andrew
Manale, U.S. Environmental Protection Agency, Washington, D.C.
The Comprehensive Environmental Economic Evaluation System (CEEPES) is an analytical
framework designed to generate trade-offs for regulating nonppint source reduction. Its current
configuration is set up to evaluate herbicide policies centered on the use., of atrazine and 15 other
chemicals in the midwestern region of the United States (Corn Belt, Lake States, Northern Plains,
Kansas).
CEEPES is a system of linked physical and economic models. The key components of the system are
(i) a mathematical programming model of agricultural decision making used to simulate producer
responses to alternative agricultural and environmental policies, (ii) physical process models used to
simulate weed competition, herbicide weather impact, and herbicide fate and transport in multiple
environmental media. The system is based on a novel approach of linking models and aggregating
their outcomes using response function methodology (metamodeling).
CEEPES evaluation includes (i) assessment of producers' substitution responses and their market
consequences, (ii) simulation of fate and transport processes which lead to herbicide concentrations
in environmental media, (iii) valuation of human risks and other damages caused by those
concentrations, and (iv) comparison of quantitative measures of the policies.
The economic indicators generated by CEEPES. for each policy option, at the producing area (PA),
state, and USDA region levels, include producer net return, cost of production, crop mix, tillage
practices, conservation practices, relations, weed control strategies, herbicide use, fertilizer use,
erosion, and commodity program participation.
The environmental indicators generated by CEEPES, for each policy option, by crop, tillage system,
soil series, county, P.A. state, and region, include groundwater concentrations at (1.2 meters, 7.0
meters, and 15 meters), surface water concentrations, air concentrations, and both surface water
and groundwater exposures (relative risk).
Atrazine is the most widely used herbicide for corn and sorghum, and one of the most commonly
encountered in surface and ground water. In addition to water quality problems, atrazine poses
hazards .through air transport, food residue, and the exposure of applicators, and wildlife. If atrazine
us'e is 'restricted, substitute herbicides will come into wider use, imposing different environmental
stress, cost or efficiency penalties, and shifts in production and resource use patterns.
The preliminary results generated are for .an atrazine ban and a triazine ban and for an atrazine post-
application (timing restriction).. We estimate that overall the benefits of an atrazine ban are
questionable since this option results in decreased producer and consumer surplus, increased risk
from other herbicides, and increased erosion. In addition, restricting application rates of atrazine to
1.5 pounds of active ingredients would not produce significant environmental benefits. A triazine ban
(atrazine, cimazine, and cyanazine) results in larger decreases in net return, increased soil erosion,
and increased risk from other herbicides, in particular the sulfonylureas. (under specific model
assumptions).
One of the most important aspects of CEEPES is a detailed characterization of weed control
technology which, in addition to standards of control measures like bans, rato restrictions, and
timing restrictions, can lend itself to the evaluation of incentive-based options such as best
management practices, and tax on chemical inputs.
Finally, we note that CEEPES framework has also been used in assessing the carbon sequestration
impacts of row crop agriculture and is being extended to produce nutrient loadings from agricultural
activity, including confined livestock operations.
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PRESENTER ADDRESSES
Diana S. Aga
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
Donald A, Goolsby
U.S. Geological Survey, WRD
MS 406, Box 25046
Bldg. 25, Denver Federal Center
Lakewood, CO 80225
Jane Nieuhues
NFS Pollution Plan for the
Delaware Drainage Area
RR 2, Box 55
Goff, KS 66428
Philip A. Banks
MARATHON-Agricultural and
Environmental Consulting,
Inc.
2649 Navajo Road
Las Cruces, NM 88005
Jerry Hatfield
U.S. Department of Agriculture
National Soil Tilth Laboratory
2150 Pammel Drive
Ames, IA50011
Michael L. Pomes
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
Philip L. Barnes
Kansas State University
6347 NW 17th
Topeka, KS 66618
John Hickman
Kansas State University
Department of Agronomy,
Crop, Soil, & Range Science
Throckmorton Hall
Manhattan, KS 66506
Stephen J. Randtke
Civil Engineering Department
University of Kansas
Lawrence, KS 66045
Aziz Bouzaher
Center for Agricultural and
Rural Development
Ames, IA 50011
Donald Huggins
Kansas Biological Survey
Nichols Hall
University of Kansas, Campus West
Lawrence, KS 66045
David Regehr
D.W. Rushing, Monsanto
Agricultural Company
Des Moines, IA
Aron Cromwell
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
Stephen Kalkhoff
U.S. Geological Survey, WRD
P.O. Box 1230
Iowa City. IA 52244
Robert J. Robel
Kansas State University
Division of Biology
Ackert Hall
Manhattan, KS 66506
Robert Dunlevy
' U.S.'Environmental Protection
Agency Region VII
726 Minnesota
Kansas City, KS 66101
Gerard J. Kluitenberg
Kansas State Department of Agronomy
Throckmorton Hall
Manhattan. KS 66506
Duane Sand
Iowa Natural Heritage
Foundation
James D. Fallon
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
Ralph Langemeier
U.S. Environmental Protection
Agency. Region VII
Drinking Water Division
726 Minnesota Ave.
Kansas City. KS 66101
Bryan Schaap
U.S. Geological Survey, WRD
P.O. Box 1230
Iowa City, IA 52244
Terry L. Gloriod
St. Louis County Water Co.
535 North New Ballas Road
St. Louis, MO 63141
Michael T. Meyer
U.S. Geological Survey. WRD
4821 Quail Crest Place
Lawrence. KS 66049-3839
Elisabeth A. Scribner
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
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J L. Sinclair
Robert S. Kerr Environmental
Research Laboratory
P.O. Box 1198
Ada, OK 74821
Sharon K. Widmer
University of Nebraska - Lincoln
Dept. of Agronomy
103 Natural Resources Hall
Lincoln, NE 68583-0844
Elizabeth Smith
364 Plant Science
University of Nebraska - Lincoln
Lincoln, NE 68583
Donald H. WilMson
U.S. Geological Survey, WRD
MS 200,
1400 Independence Road
Rolla, MO 65401
Daniel D. Snow
University of Nebraska - Lincoln
103 Natural Resources Hall
Lincoln, NE 68583-0844
Roy Spalding
University of Nebraska - Lincoln
103 Natural Resources Hall
Lincoln, NE 68583-0844
John K. Stamer
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
James Steichen
Kansas State University
Agricultural Engineering
Department
Manhattan, KS 66506
Darrell Sumner
Ciba-Geigy Corporation
P.O.'Box 18300
Greensboro, NC 27419-8300
Alan Teel
Iowa State University of
Science and Technology
117 1/2 S. Main
Oceola, IA55213
E. Michael Thurman
U.S. Geological Survey, WRD
4821 Quail Crest Place
Lawrence, KS 66049-3839
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