Soil microorganisms colonizing soil water sampling devices (lysimeters) reduced concentrations of biodegradable organic chemicals, including 2,4-dichlorophenoxyacetic acid methyl ester, alachlor, methyl m-chlorobenzoate, and metolachlor as water entered through porous ceramic cups. In some cases, losses exceeded 99%. Additions of either a biocide (sodium hypochlorite) or a bacteriostat (copper salt) prevented microbial activity so that concentrations of test chemicals inside lysimeters equaled those outside. Field studies further indicated that treating lysimeters with a copper salt effectively prevented microbial activity. Thus, chemically treating soil water samplers could improve the accuracy of soil water data for a wide variety of analytes, including environmentally important organics, such as pesticides and industrial wastes, and inorganics, such as ammonia and nitrate.
Cohen et al, 1986 reported alachlor detections in four states (Iowa, Nebraska, Pennsylvania, and Maryland) at concentrations between 1 and 10 µg/L (parts per billion). Alachlor is a herbicide used in corn, soybean, and peanut production. 2.4 million acres were treated in 1994 with alachlor and 6.6 million pounds were used (The Ground Water Gazet). Alachlor(2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide is a herbicide widely used in the United States Both has been determined in the ground water (Aga et a1.,1994). Alachlor has been classified as human carcinogen and its maximum contaminant level (MCL) was established at 2 µg/L by the United States Protection Agency (USEPA) in 1992. An evaluation of rural drinking water sources in the United States indicated that 97% is derived from underground sources, along with 55 % of all livestock water and 40 % of all irrigation water (Pepperman and Kuan, 1994). Ground water studies in Virginia by Gallagher et al (1996) indicated the presence of alachlor in 18 percent of the samples at levels mostly < 1 µg/L. Richards et al (1995) sampled nearly 35,000 wells in Ohio, Indiana, Illinois, West Virginia, and Kentucky. 1.1 percent of the wells were above 2 µg/L for alachlor in this survey. No information was given on the persistence of alachlor in well water that can be expected once contamination has been detected. The following observations are therefore being reported. Over 200 wells were sampled in Florida and 16 wells containing alachlor at levels near or over 2 µg/L were sampled since 1989 to present. Alachlor concentrations remained > 2 µg/L in all but four wells. One well which was initially < 2 µg/L went over that level in 1994. The mean of alachlor in all wells was 13 µg/L and 9 µg/L, in 1994 and 1995, respectively. All alachlor use in Florida was canceled before the 1991 use season but sampling periods did not indicate a discernable trend. As a group, the concentrations of the alachlor were not significantly different with time no matter how sampling intervals were analyzed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.