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This article in JEQ

  1. Vol. 34 No. 3, p. 793-803
     
    Received: Nov 24, 2003
    Published: May, 2005


    * Corresponding author(s): noel.deguzman@lfr.com
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doi:10.2134/jeq2003.0412

The Acetochlor Registration Partnership State Ground Water Monitoring Program

  1. Noel P. de Guzman *a,
  2. Paul Hendleyb,
  3. David I. Gustafsonc,
  4. Ian van Wesenbeeckd,
  5. Andrew J. Kleine,
  6. John D. Fuhrmanc,
  7. Kim Travisf,
  8. Nick D. Simmonsd,
  9. Wendy E. Teskeyg and
  10. Roger B. Durhamh
  1. a LFR Levine·Fricke, 1900 Powell Street, 12th Floor, Emeryville, CA 94608
    b Syngenta Crop Protection, P.O. Box 18300, Greensboro, NC 27419
    c Monsanto Company, 800 North Lindbergh Boulevard, St. Louis, MO 63167
    d Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268
    e Klein & Associates, LLC, 12917 Topping Estates Drive, Town & Country, MO 63131
    f Syngenta Ltd., Jealott's Hill Research Station, Bracknell, Berkshire, England RG42 6ET
    g LFR Levine·Fricke, 630 Tollgate Road, Suite D, Elgin, IL 60123
    h LFR Levine·Fricke, 3382 Capital Circle NE, Tallahassee, FL 32308

Abstract

The Acetochlor Registration Partnership (ARP) conducted a 7-yr ground water monitoring program at a total of 175 sites in seven states: Illinois, Indiana, Iowa, Kansas, Minnesota, Nebraska, and Wisconsin. While acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide] was the primary focus, the analytical methods also quantified alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide], atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide], and two classes of soil degradates for acetochlor, alachlor, and metolachlor. Ground water samples were collected monthly for five years and quarterly for two additional years. All samples were analyzed for the presence of parent herbicides, and degradates were monitored during the last three years. Parent acetochlor was detected above 0.1 μg L−1 in three or more samples at just seven sites. Alachlor and metolachlor were also rarely detected, but atrazine was detected in 36% of all samples analyzed. Even more widespread were the tertiary amide sulfonic acid (ethanesulfonic acid, ESA) degradates of acetochlor, alachlor, and metolachlor, which were detected at 81, 76, and 106 sites, respectively. The other class of monitored soil degradates (oxanilic acid, OXA) was detected less frequently, at 26, 16, and 63 sites for acetochlor OXA, alachlor OXA, and metolachlor OXA, respectively. The geographic distribution of detections did not follow the pattern originally expected when the study began. Rather than being a function primarily of soil texture, the detection of these herbicides in shallow ground water was related to site-specific factors associated with local topography, the occurrence of surface water drainage features, irrigation practices, and the vertical positioning of the well screen.

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