Small-Scale Retrospective Ground Water Monitoring Study for Simazine in Different Hydrogeological Settings |
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| Authors: | Paul H. Roux Robert L. Hall Richard H. Ross Jr. |
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| Affiliation: | Paul Roux is president of Roux Associates Inc. (775 Park Ave., Suite 255, Huntington, NY 11743), a consulting ground water firm that specializes in pesticide monitoring studies and hazardous waste investigations. Previous to founding the firm, he was a senior hydrogeologist with Stauffer Chemical Co. and with Geraghty &Miller Inc. He has 18 years of experience in the field of hydrogeology. He holds a B.S. in engineering science from C. W. Post College and an M.S. in geology from Queens College of the City University of New York.;Robert L. Hall is a senior geochemist with Roux Associates Inc. (775 Park Ave., Suite 255, Huntington, NY 11743). He has 11 years of experience in environmental chemistry, including three years with the Environmental Protection Agency. He holds a B.A. in chemistry from Swarthmore College and a Ph.D. in biochemistry from The University of Chicago.;Richard H. Ross Jr. is manager of Environment and Contract Studies in the Agricultural Division of CIBA-GEIGY in Greensboro, North Carolina (P.O. Box 18300, 410 Swing Rd., Greensboro, NC 27419). He has 17 years of experience in biological and environmental research, and holds a Ph.D. in insect biochemistry from Michigan State University. |
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| Abstract: | A ground water monitoring study was conducted for the triazine herbicide simazine at 11 sites in the United States. The study used carefully selected, small-scale sites (average size: about 33 acres) with documented product use and sensitive hydrogeological settings. The sites selected were Tulare County, California (two sites); Fresno County, California; Sussex County, Delaware; Hardee and Palm Beach counties, Florida; Winnebago County, Illinois; Jackson County, Indiana; Van Buren and Berrien counties, Michigan; and Jefferson County, West Virginia. These sites satisfied the following criteria: a history of simazine use, including the year prior to the start of the study; permeable soil and vadose zone; shallow depth to water; no restrictive soil layers above the water table; and gentle slopes not exceeding 2 percent. A variety of crop types, climates, and irrigation practices were included. Monitoring well clusters (shallow and deep) were installed at each site except in California and West Virginia, where only shallow wells were installed. Simazine was monitored at these sites at quarterly intervals for a two-year period during 1986–1988.
The results of the study showed that out of 153 samples analyzed, 45 samples showed simazine detections. A substantial majority of the detections (32 out of 45) occurred in Tulare, Fresno, and Jefferson counties. The detections in these areas were attributed to mechanisms other than leaching, such as drainage wells, karst areas, surface water recharge, or point source problems. An additional 11 detections in Van Buren County were apparently due to an unknown upgradient source. Only one detection (in Palm Beach County, Florida) near the screening level of 0.1 ppb was attributed to possible leaching. The results of this investigation support the hypothesis that simazine does not leach significantly under field use conditions. |
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