Occurrence of Selected Pesticides and Their Metabolites in Near-Surface Aquifers of the Midwestern United States

Abstract

The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to be found more frequently in groundwater than its parent compound. The metabolite alachlor ethanesulfonic acid (alachlor-ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid) was detected almost 10 times as frequently and at much higher concentrations than its parent compound alachlor (2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetamide). The median detectable atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) concentration was almost half that of atrazine residue (atrazine plus the two atrazine metabolites analyzed). Cyanazine amide [2-chloro-4-(1-carbamoyl-1-methylethylamino)-6-ethylamino-s-triazine] was detected almost twice as frequently as cyanazine (2-chloro-4-ethylamino-6-methylpropionitrileamino-s-triazine). Results show that information on pesticide metabolites is necessary to understand the environmental fate of pesticides. Consequently, if pesticide metabolites are not quantified, the effects of chemical use on groundwater quality would be substantially underestimated. Thus, continued research is needed to identify major degradation pathways for all pesticides and to develop analytical methods to determine their concentrations in water and other environmental media.

Occurrence of Cyanazine Compounds in Groundwater: Degradates More Prevalent Than the Parent Compound

“…Only cyanazine however has such a criteria establishedshaving an unenforceable health advisory level set at 1.0 µg/L. Making the gross assumption that the chlorinated degradates may have similar toxicity as the parent compoundssimilar to what has been found with the The results of this study documented that data on the degradates for cyanazine are critical for understanding its fate and transport in the hydrologic system, similar to what has been found with acetochlor, alachlor, atrazine, and metolachlor (3,4,25,26). Furthermore, the prevalence of the chlorinated degradates of cyanazine found in groundwater suggests that to accurately determine the overall effect of cyanazine on human health and the environment its degradates should also be considered.…”

“…Indeed, research has documented the presence of CAM and DIA in groundwater (3,4). Little data have been obtained on the environmental occurrence of other cyanazine degradates due to the inherent difficulty in measuring these compounds (15).…”

A field study to assess the degradation and transport of diuron and its metabolites in a calcareous soil

“…In the United States, a considerable body of work exists relating to the occurrence of both parent compound pesticides and their metabolites in aquifers (Thurman et al, 1992;Baker et al, 1993;Lawrence et al, 1993;Kolpin et al, 1996;Kolpin et al, 1998;Kolpin et al, 2000a;Kolpin et al, 2000b). In the UK the number of field studies has been limited (Clark et al, 1991;Gooddy et al, 2001;Johnson et al, 2001) with researchers often concentrating on laboratory studies of transport and degradation potential (Johnson et al, 1998;Besien et al, 2000;.…”

Peer Reviewed: When Synthetic Chemicals Degrade in the Environment

“…Specifically, research on pesticides has found degradates in surface water (5)(6)(7)(8)(9)(10), groundwater (11)(12)(13), precipitation (14)(15)(16), air (17,18), and sediment (19,20).…”