HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (63) Citing Articles via Google Scholar Google Scholar Articles by Barbash, J. E. Articles by Gilliom, R. J. Search for Related Content PubMed PubMed Citation Articles by Barbash, J. E. Articles by Gilliom, R. J. GeoRef GeoRef Citation Agricola Articles by Barbash, J. E. Articles by Gilliom, R. J. Related Collections Ground Water Quality Agricultural Pesticides Water Pollution

Major Herbicides in Ground Water

Results from the National Water-Quality Assessment

^a U.S. Geological Survey (USGS), 1201 Pacific Ave., Suite 600, Tacoma, WA 98402
^b USGS, Placer Hall, 6000 J Street, Sacramento, CA 95819-6129
^c USGS, 400 S. Clinton St., Box 1230, Iowa City, IA 52244

View larger version (48K): [in a new window]   Fig. 1. Concentrations of herbicides measured in ground water at individual sites during the NAWQA investigation, in relation to drinking-water quality criteria (USEPA, 2000). Lifetime health advisory level (HAL) shown for herbicides for which no maximum contaminant level (MCL) has been established. (Neither criterion has yet been established for acetochlor.) Overall percentage of sites with no detections given above the not detected symbols for each herbicide. Number of sites sampled for each study component given in Fig. 2. LUSs, land-use studies; SUSs, subunit surveys.

View larger version (49K): [in a new window]   Fig. 2. Frequencies of herbicide detection in ground water from 1993 to 1995, by study component, during the NAWQA investigation. Numbers of sites sampled for acetochlor given in brackets. LUSs, land-use studies; SUSs, subunit surveys.

View larger version (47K): [in a new window]   Fig. 3. Agricultural and nonagricultural use of the seven herbicides of interest. Estimates of nationwide rates of agricultural use per year are from 1991 to 1995 (Gianessi and Anderson, 1996); estimates for rates of nonagricultural use per year are from 1987 to 1990 (Gianessi and Puffer, 1990). Information on application settings was obtained from Gianessi and Puffer (1990) for agricultural use, and from a variety of sources for nonagricultural use. a.i., active ingredient.

View larger version (25K): [in a new window]   Fig. 4. Frequencies of herbicide detection in ground water for the multistate studies in relation to reporting limits for (a) atrazine, and (b) metolachlor. CGAS, Ciba-Geigy Atrazine Study (Balu et al., 1998); LUSs, land-use studies; MMS, Metolachlor Monitoring Study (Roux et al., 1991); MWPS, Midwest Pesticide Study (Kolpin et al., 1995); NAWWS, National Alachlor Well-Water Survey (Holden et al., 1992); NPS, National Pesticide Survey (USEPA, 1990, 1992a); SUSs, subunit surveys; t1/2, half-life for transformation in aerobic soil.

View larger version (40K): [in a new window]   Fig. 5. Frequencies of herbicide detection in shallow ground water for NAWQA land-use studies conducted in agricultural areas, in relation to total agricultural use within a 1-km radius of all sites sampled for each study. Studies with zero use assigned a value of 0.001 kg a.i. per square kilometer to accomodate log scale (see text). a.i., active ingredient; R2, coefficient of determination for linear correlation; , Spearman's rank correlation coefficient; t1/2, half-life for herbicide transformation in aerobic soil. *, ** Statistically significant at the 0.05 and 0.001 probability levels, respectively.

View larger version (54K): [in a new window]   Fig. 6. Frequencies of herbicide detection in ground water for the NAWQA study in relation to agricultural use (Gianessi and Anderson, 1996); (a) atrazine, (b) metolachlor. LUSs, land-use studies; SUSs, subunit surveys.