Alachlor pesticide-contaminated

The documented occurrence of pesticides in surface water is indicative that mnoff is an important pathway for transport of pesticide away from the site of appHcation. An estimated 160 t of atra2ine, 71 t of sima2ine, 56 t of metolachlor, and 18 t of alachlor enter the Gulf of Mexico from the Mississippi River annually as the result of mnoff (47). Field appHcation of pesticides inevitably leads to pesticide contamination of surface mnoff water unless mnoff does not occur while pesticide residues remain on the surface of the soil. The amount of pesticides transported in a field in mnoff varies from site to site. It is controUed by the timing of mnoff events, pesticide formulation, physical—chemical properties of the pesticide, and properties of the soil surface (48). Under worst-case conditions, 10% or more of the appHed pesticide can leave the edge of the field where it was appHed. 

Most of the common pesticides used now and in the past have also been found in the atmosphere, including DDT, toxaphene, dieldrin, heptachlor, organophosphorous insecticides, triazine herbicides, alachlor and metolachlor. These airborne pesticides return to the earth with rainfall to further contribute to water contamination. A recent... 

Synthetic organic contaminants including pesticides and herbicides such as the following 2,4-D, 2,4,5-TP (Silvex), acrylamide, Alachlor, atrazine, benzoapyrene, carbofuran, Chlordane, dalapon, di-2-ethylhexyl adipate, di-2-ethylhexyl phtha-late, dibromochloropropane, Dinoseb, dioxin (2,3,7,8-TCDD), Diquat, Endothall, Endrin, epic-hlorohydrin, ethylene dibromide, glyphosate, He-ptachlor, Heptachlor epoxide, hexachlorobenzene. 

Laboratory standards were obtained for these new compoundsand the sampling area was expanded. By March 21, 1984, six private wells were found to be contaminated, two with PCBs and four with pesticides. By the middle of May, 15 wells had been found to be contaminated with pesticides, six with PCBs and/or chlorinated hydrocarbon solvents and one with both pesticides and PCBs. In addition to drinking water wells, springs in the areas were found to be contaminated. The highest levels found for the pesticides were 260 ug/1 for atrazine and 660 ug/1 for alachlor. 

GC-MS total ion chromatograms obtained under xSIS acquisition after SPME extraction of a 0.1 (xg/L spiked sample (above) and a contaminated groundwater sample (below) containing the following pesticide concentrations atrazine 0.043 pg/L, lindane 0.006 xg/L, alachlor 0.020 M-g/L, procymidone 0.068 xg/L, endosulfan I 0.115 (xg/L, dieldrin not quantitated, endosulfan II 0.108 (xg/L, and endosulfan sulfate 0.597 xg/L. (Reprinted from Congalves, C. and Alpendurada, M.F., /. Chromatogr. A, 1026,239,2004. With permission.)... 

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