title: Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins.
abstract: BACKGROUND
  Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used widely throughout the world in the production of many crops and is heavily used on soybeans, corn and cotton. Glyphosate is used in almost all agricultural areas of the United States, and the agricultural use of glyphosate has increased from less than 10 000 Mg in 1992 to more than 80 000 Mg in 2007. The greatest intensity of glyphosate use is in the midwestern United States, where applications are predominantly to genetically modified corn and soybeans. In spite of the increase in usage across the United States, the characterization of the transport of glyphosate and its degradate aminomethylphosphonic acid (AMPA) on a watershed scale is lacking.
  
  
  RESULTS
  Glyphosate and AMPA were frequently detected in the surface waters of four agricultural basins. The frequency and magnitude of detections varied across basins, and the load, as a percentage of use, ranged from 0.009 to 0.86% and could be related to three general characteristics: source strength, rainfall runoff and flow route.
  
  
  CONCLUSIONS
  Glyphosate use in a watershed results in some occurrence in surface water; however, the watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff and a flow route that does not include transport through the soil.
authors.affiliation: US Geological Survey, Pearl, MS, USA. rhcoupe@usgs.gov
authors.forename: Richard H
authors.initials: RH
authors.lastname: Coupe
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kalkhoff
authors.forename: Paul D
authors.initials: PD
authors.lastname: Capel
authors.forename: Caroline
authors.initials: C
authors.lastname: Gregoire
mesh_terms: D004784:Environmental Monitoring; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis; D006540:Herbicides / Q000032:analysis*; D007555:Isoxazoles; D063065:Organophosphonates / Q000032:analysis*; D013777:Tetrazoles; D014481:United States; D014874:Water Pollutants, Chemical / Q000032:analysis*; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D007555:Isoxazoles; D063065:Organophosphonates; D013777:Tetrazoles; D014874:Water Pollutants, Chemical; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid