Major Herbicides in Ground Water: Results from the National Water‐Quality Assessment

Abstract

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2,227 sites (wells and springs) sampled in 20 major hydrologic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides--atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis-[ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N-[methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxylethyl]acetamide)--as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 microg L(-1) at 98% of the sites with detections, but exceeded drinking-water criteria (for atrazine) at two sites. In urban areas, frequencies of detection (at or above 0.01 microg L(-1)) of atrazine, cyanazine, simazine, alachlor, and metolachlor in shallow ground water were positively correlated with their nonagricultural use nationwide (P < 0.05). Among different agricultural areas, frequencies of detection were positively correlated with nearby agricultural use for atrazine, cyanazine, alachlor, and metolachlor, but not simazine. Multivariate analysis demonstrated that for these five herbicides, frequencies of detection beneath agricultural areas were positively correlated with their agricultural use and persistence in aerobic soil. Acetochlor, an agricultural herbicide first registered in 1994 for use in the USA, was detected in shallow ground water by 1995, consistent with previous field-scale studies indicating that some pesticides may be detected in ground water within 1 yr following application. The NAWQA results agreed closely with those from other multistate studies with similar designs.

Anodic oxidation of mecoprop herbicide at lead dioxide

“…However, the extensive use of these substances has contributed to pollution of the environment, so residual herbicides along with their degradation byproducts have been found in surface waters, wastewaters and even in drinking waters [1]. Therefore, there is an increasing interest in reliable technologies for their removal.…”

Sorption of the Herbicide Dichlobenil and the Metabolite 2,6-Dichlorobenzamide on Soils and Aquifer Sediments

“…In recent years, herbicides and their degradation products have been detected in an increasing number of aquifers all over the world, including Europe (1) and the United States (2). One of the problematic compounds is the herbicide dichlobenil (2,6-dichlorobenzonitrile), since its discharge into groundwater can result in widespread presence of its metabolite 2,6-dichlorobenzamide (BAM) ( Table 1).…”

“…Furthermore, the main purpose is to improve the understanding of controlling parameters for sorption of both polar (BAM) and nonpolar (dichlobenil) nonionic compounds by (1) determining the contribution to sorption from common aquifer minerals by investigating sorption to quartz, calcite, clay minerals (kaolinite, montmorillonite), and iron oxides (goethite, lepidocrocite); (2) determining the contribution to sorption from organic carbon by correlating sorption and content of organic carbon in the sediments and by investigating the effect on sorption by removing organic carbon from reduced clayey till sediments by hydrogen peroxide treatment; and (3) determining the influence of redox status on sorption by investigating sediment samples from both oxidized and reduced clayey till aquitards.…”

Assessing Exposure to Atrazine and Its Metabolites Using Biomonitoring

“…ATZ and its degradates are the most commonly detected pesticide(s) in ground and surface waters (Aaronson et al 1980; Appel and Hudak 2001; Barbash et al 2001; Barnes and Kalita 2001; Battaglin et al 2000; Bushway et al 1992; Clark and Clay et al 2000; Goolsby 2000; Gaynor et al 2002). It has been the subject of multiple monitoring programs conducted by various industry and government agencies, especially the U.S. Geological Survey (USGS) (Barbash et al 2001).…”