Glyphosate in the atmosphere and in rivers and streams
Note from GM-Free Cymru: We have a tendency to think that glyphosate is a problem just in the immediate areas where it is being applied, with dramatic consequences for human and animal health and for non-target organisms. However, evidence is accumulating that Roundup formulations and glyphosate do a great deal of harm to the environment and to ecological health well away from the immediate impact areas -- through transport in the atmosphere and through surface runoff into streams and rivers. Spray drift in the wind and the washing off of glyphosate from plant leaves during periods of rain are major factors. These two papers from 2011 give a timely reminder of the scale of the problem and of how the "chemical load" in the environment is becoming greater and greater in areas where RR crops are grown on an industrial scale.
OCCURRENCE AND FATE OF THE HERBICIDE GLYPHOSATE AND ITS DEGRADATE AMINOMETHYLPHOSPHONIC ACID IN THE ATMOSPHERE
FENG-CHIH CHANG, MATT F. SIMCIK, and PAUL D. CAPEL
Environmental Toxicology and Chemistry, Vol. 30, No. 3, pp. 548–555, 2011
Accepted 16 September 2010
Abstract
This is the first report on the ambient levels of glyphosate, the most widely used herbicide in the United States, and its major degradation product, aminomethylphosphonic acid (AMPA), in air and rain. Concurrent, weekly integrated air particle and rain samples were collected during two growing seasons in agricultural areas in Mississippi and Iowa. Rain was also collected in Indiana in a preliminary phase of the study. The frequency of glyphosate detection ranged from 60 to 100% in both air and rain. The concentrations of glyphosate ranged from <0.01 to 9.1 ng/m3 and from <0.1 to 2.5mg/L in air and rain samples, respectively. The frequency of detection and median and maximum concentrations of glyphosate in air were similar or greater to those of the other high-use herbicides observed in the Mississippi River basin, whereas its concentration in rain was greater than the other herbicides. It is not known what percentage of the applied glyphosate is introduced into the air, but it was estimated that up to 0.7% of application is removed from the air in rainfall. Glyphosate is efficiently removed from the air; it is estimated that an average of 97% of the glyphosate in the air is removed by a weekly rainfall 30 mm. Environ. Toxicol. Chem. 2011;30:548–555.
Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins
Richard H Coupe, Stephen J Kalkhoff, Paul D Capel and Caroline Gregoire
Accepted: 26 April 2011 Pest Manag Sci (2011) www.soci.org Published online inWiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/ps.2212
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.