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Distribution of Major Herbicides in Ground Water of the United States

By Jack E. Barbash, Gail P. Thelin, Dana W. Kolpin, and Robert J. Gilliom

U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 98-4245
Sacramento, California, 1999



Text Only version (137K)
Download PDF Formats:
Entire Report (64 pages, 3.4M)
Contents, Pages 1-31 (380K), Pages 32-43 (1.2M), Pages 44-47 (1M), Pages 48-57

CONTENTS

Abstract
Introduction
Factors That Influence Pesticide Occurrence in Ground Water
History and Patterns of Use
Physical and Chemical Properties
Hydrogeologic Setting
Study Designs
Overview of Non-USGS Regional and National Studies of Pesticides in Ground Water
General Features
Analytical Coverage of the Subject Compounds
Spatial Scope
Spatial Bias Toward Potentially Contaminated Areas
Comparisons Between Agricultural and Nonagricultural Areas
National Water-Quality Assessment (NAWQA)
Midwest Pesticide Study (MWPS)
Adjustment of Detection Frequencies to a Common Reporting Limit
Comparisons of NAWQA and MWPS Results
Occurrence of Major Herbicides and their Degradates in Ground Water
Co-occurrence
Concentrations
Degradates
Factors Affecting Herbicide Occurrence
Geographic Relations Between Occurrence and Use of Herbicides
Atrazine
Prometon
Simazine
Metolachlor
Alachlor
Cyanazine
Acetochlor
Comparisons of Observed Concentrations with Drinking-Water Criteria
Limitations of Existing Drinking-Water Criteria for Assessing Overall Health Risks
Summary and Concluding Remarks
Acknowledgments
References Cited

FIGURES

   1. Graph showing total nationwide agricultural use of the seven herbicides of interest 
      from 1964 to 1994
 2-5. Maps showing:
        2. Study units of the NAWQA Program
        3. Areas sampled for the NAWQA land-use studies discussed in this report
        4. Areas sampled for the NAWQA subunit surveys discussed in this report 
        5. Hydrogeologic settings tapped by the 94 wells sampled in 1992 for the MWPS
6-13. Graphs showing:
        6. Pesticide compounds detected most frequently in ground water for the NAWQA study 	
        7. Frequencies of herbicide detection in ground water during the NAWQA (1993-1995) and 
           MWPS (1992) investigations
        8. Frequencies of herbicide detection for individual ground-water studies of NAWQA,
           relative to land-use setting and well depth 	
        9. Percentages of sampled sites with multiple herbicide detections, on the basis of their original 
           reporting limits, for the NAWQA and MWPS investigations 
       10. Frequencies of PMP herbicide detection in shallow ground water beneath urban areas for the
           NAWQA study in relation to nationwide nonagricultural use 
       11. Frequencies of PMP herbicide detection in shallow ground water for the 39 NAWQA studies 
           undertaken in agricultural areas in relation to agricultural use within a 1-kilometer radius 
           surrounding all sites sampled for each study
       12. Ratio of the frequency of detection of any degradate of a given herbicide to the frequency of  
           detection of the parent compound in 88 municipal wells in Iowa in relation to the transformation  
           half-life of the parent compound in aerobic soil 	
       13. Frequencies of herbicide detection in ground water for the various stages of the MWPS
       14. Map showing physical divisions of the United States	
       15. Graph showing frequencies of atrazine detection in ground water for the multistate studies in 
           relation to reporting limits
16-17. Maps showing
       16. Atrazine occurrence in ground water for the NAWQA study in relation to agricultural use 
           (A) Frequencies of detection. (B) Upper 90th-percentile concentrations
       17. Concentrations of atrazine in near-surface aquifers of the northern midcontinent for the 1992 
           sampling of the MWPS in relation to agricultural use 		
       18. Graph showing frequencies of prometon detection in ground water for the multistate studies in 
           relation to reporting limits 				
19-20. Maps showing:
       19. Prometon occurrence in ground water for the NAWQA study  (A) Frequencies of detection. 
           (B) Upper 90th-percentile concentrations	
       20. Prometon concentrations measured in near-surface aquifers of the northern midcontinent for the 
           1992 sampling of the MWPS 
   21. Graph showing frequencies of simazine detection in ground water for the multistate studies in 
       relation to reporting limits 
22-23. Maps showing:
       22. Simazine occurrence in ground water for the NAWQA study in relation to agricultural use 
           (A) Frequencies of detection. (B) Upper 90th-percentile concentrations	
       23. Concentrations of simazine in near-surface aquifers of the northern midcontinent for the 
           1992 sampling of the MWPS in relation to agricultural use 
   24. Graph showing frequencies of metolachlor detection in ground water for the multistate studies in 
	   relation to reporting limits	
25-26. Maps showing:
       25. Metolachlor occurrence in ground water for the NAWQA study in relation to agricultural use
           (A) Frequencies of detection. (B) Upper 90th-percentile concentrations	
       26. Concentrations of metolachlor in near-surface aquifers of the northern midcontinent for the 
           1992 sampling of the MWPS in relation to agricultural use 
   27. Graph showing frequencies of alachlor detection in ground water for the multistate studies 
	   in relation to reporting limits 			
28-29. Maps showing:
       28. Alachlor occurrence in ground water for the NAWQA study in relation to agricultural use
           (A) Frequencies of detection. (B) Upper 90th-percentile concentrations	
       29. Concentrations of alachlor in near-surface aquifers of the northern midcontinent for the 1992 
           sampling of the MWPS in relation to agricultural use 
   30. Graph showing frequencies of cyanazine detection in ground water for the multistate studies 
	   in relation to reporting limits 				
31-32. Maps showing:
       31. Cyanazine occurrence in ground water for the NAWQA study in relation to agricultural use 
           (A) Frequencies of detection. (B) Upper 90th-percentile concentrations	
       32. Concentrations of cyanazine in near-surface aquifers of the northern midcontinent for the 1992 
           sampling of the MWPS in relation to agricultural use 
       33. Graph showing concentrations of herbicides measured in ground water at individual sites during 
           the NAWQA and MWPS investigations in relation to drinking-water criteria

TABLES

 1. Factors associated with pesticide detections in ground water and the nature of supporting evidence 
    in the literature 
 2. Annual nationwide agricultural and nonagricultural use of the herbicides of interest to this report 		
 3. Selected physical and chemical properties of the seven parent compounds of interest to this report and 
    their degradates examined in ground water 
 4. Principal characteristics of multistate studies 
 5. Comparison of principal design features of the multistate investigations of pesticides in ground water 		
 6. Degradates examined by the multistate studies for the seven herbicides 
 7. Criteria used by multistate studies for selection of sampling sites 	
 8. Principal characteristics of the NAWQA land-use studies and subunit surveys discussed in this report						
 9. Co-occurrence of herbicide compounds at sites with two or more of the compounds detected at or above
    their original reporting limits during the NAWQA and MWPS investigations 	
10. Upper 90th-percentile concentrations of the seven herbicides of interest measured in ground water by the 
    NAWQA and MWPS investigations 	
11. Frequencies of detection of herbicide degradates in comparison with those for the corresponding 
    parent compounds 
12. Frequencies of detection of the herbicides of interest and selected degradates during the 1996 statewide 
    sampling of 88 municipal wells in Iowa 
13. Frequencies of detection of the seven herbicides of interest at or above 0.05 microgram per liter
    during the NAWQA and MWPS investigations 


CONVERSION FACTORS, WATER QUALITY UNITS, AND ABBREVIATIONS AND ACRONYMS

Conversion Factors

----------------------------------------------------------------------    
                   Multiply       By        To obtain
----------------------------------------------------------------------
                  foot (ft)     0.3048      meter (m)
                  mile (mi)     1.609       kilometer (km)
    pound, avoirdupois (lb)     0.45359     kilogram (kg)
----------------------------------------------------------------------

Temperature is given in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by the following equation:

                          °F=1.8(°C)+32.

Abbreviations and Acronyms
(Additional information noted in parentheses)

kg/km2, kilogram per square kilometer
km, kilometer
lb a.i., pound active ingredient
m, meter
µg/L, microgram per liter
mg/L, milligram per liter
mL/g, milliliter per gram

a.i., active ingredient
CDP, construction data preferred
CDR, construction data required
CGAS, Ciba-Geigy atrazine study
CPWTP, Cooperative Private Well Testing Program
CWSW, community water-supply wells
DEA, deethylatrazine
DIA, deisopropylatrazine
DRASTIC, scoring system for predicting the vulnerability of ground water to contamination
DWA, drinking-water aquifer
ESA, ethanesulfonic acid
GC/MS, gas chromatography/mass spectrometry
H, HenryUs law constant
HAL, health advisory level
Koc, soil organic carbon partition coefficient
LUS, land-use study (NAWQA)
MCL, maximum contaminant level
MDL, method detection limit
MMS, Metolachlor Monitoring Study
MWPS, Midwest Pesticide Study
NAWQA, National Water-Quality Assessment (Program)
NAWWS, National Alachlor Well-Water Survey
NPS, National Pesticide Survey
OA, oxanilic acid
PMP, Pesticide Management Plan
RDW, rural domestic wells
SGW, shallow ground water
SUS, subunit survey (NAWQA)
Sw, water solubility
USDA-ARS, U.S. Department of Agriculture-Agricultural Research Service
USEPA, U.S. Environmental Protection Agency
USGS, U.S. Geological Survey

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