The acetochlor registration partnership state ground water monitoring program.
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 microg 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.
de Guzman
Noel P
NP
LFR Levine Fricke, 1900 Powell Street, Emeryville, CA 94608, USA. noel.deguzman@lfr.com
Hendley
Paul
P
Gustafson
David I
DI
van Wesenbeeck
Ian
I
Klein
Andrew J
AJ
Fuhrman
John D
JD
Travis
Kim
K
Simmons
Nick D
ND
Teskey
Wendy E
WE
Durham
Roger B
RB
D000383:Agriculture; D004784:Environmental Monitoring; D006540:Herbicides / Q000032:analysis*; D012987:Soil; D014052:Toluidines / Q000032:analysis*; D014481:United States; D014873:Water Pollutants / Q000032:analysis*
D006540:Herbicides; D012987:Soil; D014052:Toluidines; D014873:Water Pollutants; C043377:acetochlor