Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins.
TL;DR: 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.
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 10000 Mg in 1992 to more than 80000 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 aminomethylphosphonicacid (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 andflow 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. c � 2011 Society of Chemical Industry
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TL;DR: G glyphosate is a transitional herbicide; therefore, its leaching potential in the soil is low, despite the addition of cow dung or rice husk ash, which could be beneficial in increasing adsorption and enhancing degradation of these compounds.
Abstract: This study investigates adsorption-desorption and the leaching potential of glyphosate and aminomethylphosphonic acid (AMPA) in control and amended—addition of cow dung or rice husk ash—acidic Malaysian soil with high oxide mineral content. The addition of cow dung or rice husk ash increased the adsorptive removal of AMPA. The isotherm data of glyphosate and AMPA best fitted the Freundlich model. The constant Kf for glyphosate was high in the control soil (544.873 mg g−1) followed by soil with cow dung (482.451 mg g−1) then soil with rice husk ash (418.539 mg g−1). However, for AMPA, soil with cow dung was high (166.636 mg g−1) followed by soil with rice husk ash (137.570 mg g−1) then the control soil (48.446 mg g−1). The 1/n values for both glyphosate and AMPA adsorptions were < 1 indicating their strong affinity for adsorbents. Desorption of both glyphosate and AMPA occurred only in the control soil. The compounds were not detected in soils with added cow dung or rice husk ash. The addition of cow dung or rice husk ash increased glyphosate mobility. However, ground water ubiquity scores for both control and amended soils were < 2.8. This indicated glyphosate is a transitional herbicide; therefore, its leaching potential in the soil is low, despite the addition of cow dung or rice husk ash. Addition of these wastes decreased the mobility and leaching potential of AMPA. The addition of cow dung or rice husk ash could be beneficial in increasing adsorption and enhancing degradation of these compounds.
13 citations
01 Apr 2019
13 citations
Cites background from "Fate and transport of glyphosate an..."
...%) planted in 2007 were glyphosate tolerant (Coupe et al. 2012)....
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...Coupe et al. (2012) studied the glyphosate levels at three locations located in the United States (South Fork River Basin, Iowa; Sugar Creek River Basin, Indiana; and Bogue Phalia Basin, Mississippi)....
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TL;DR: The present study does constitute the first extended soil monitoring survey of glyphosate and AMPA with samples derived during the years 2013–2015, from the highest extent of the Greek territory, and can constitute a basis for the determination of the background concentration levels of Monsanto's glyphosate and its metabolite in theGreek territory.
Abstract: Glyphosate is a broad-spectrum, non-selective, post-emergence herbicide that controls weeds by inhibiting their ability to synthesize amino acids. It is characterized by high persistence and adsorption to soil, with its dissipation to be highly correlated to the climatic conditions. After its degradation in soil, aminomethylphosphonic acid (AMPA) is the sole and major metabolite produced, characterized also by high persistence and adsorption. Both substances have the potential to remain in soil rather than move to other environmental compartments. Considering the recent intense debate during the EU renewal of glyphosate along with its wide use, it is apparent that both glyphosate and AMPA require further attention and information on their occurrence and distribution in EU soils. The present study does constitute the first extended soil monitoring survey of glyphosate and AMPA with samples derived during the years 2013–2015, from the highest extent of the Greek territory. Specific attention was given to areas of high agricultural production as well as to urban areas, since glyphosate-containing products are also registered for non-professional uses. The positive samples represented the 36.7% for glyphosate and 44.9% for AMPA, while the detected residues fluctuated from 0.026 to 40.6 μg g−1 and from 0.01 to 2.5 μg g−1 for glyphosate and AMPA, respectively. Our findings can constitute a basis for the determination of the background concentration levels of glyphosate and its metabolite in the Greek territory. As such, apart from being the first study for glyphosate monitoring in Greece, the most significant highlights recognized in the present work are the following:
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TL;DR: The most frequently used pesticides were organophosphates (28.87%), pyrethroids (12.89%), and the herbicide paraquat (31.95%), while the prevalent pesticides were glyphosate (56.96-510.46 and malathion (311.76-863.49) as discussed by the authors.
Abstract: Sixty percent of global agricultural production depends on the use of pesticides, despite their adverse effects on human health and the ecosystem. In Mexico, the application of these products has been exacerbated, including pesticides already banned in other countries. The objective of this study was to determine pesticide concentrations in samples of water purification plants and surface water from the Cienega area of Jalisco, Mexico. A survey of 119 farmers with occupational exposure to pesticides was carried out in order to obtain information on the most frequently used pesticides. Subsequently, 51 samples taken at 7 different sites were analyzed using liquid chromatography and mass-mass spectrometry. The most frequently used pesticides were organophosphates (28.87%), pyrethroids (12.89%), and the herbicide paraquat (31.95%). In surface water, the prevalent pesticides were glyphosate (56.96–510.46 ppb) and malathion (311.76–863.49 ppb). Glyphosate levels were higher than the limits acceptable in daily water intake in Cumuato. Malathion levels exceeded the limits permissible by EPA in water purification plants in urban public establishments (100 ppb for children, and 200 ppb for adults). In addition, a multidimensional scaling analysis showed that the sampled sites could be grouped into 2 different bodies of water, based on similarities in their glyphosate concentrations (stress = 0.005), while the concentrations of malathion were heterogeneous (stress = 0.001).
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TL;DR: In this article, the concentration of glyphosate and its breakdown product, aminomethylphosphonic acid (AMPA), in Florida manatee plasma and assess their exposure to manatees seeking a warm-water refuge in Crystal River (west central Florida), and in South Florida.
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References
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TL;DR: Glyphosate-based weed control products are among the most widely used broad-spectrum herbicides in the world and have been extensively investigated for their potential to produce adverse effects in nontarget organisms as discussed by the authors.
Abstract: Glyphosate-based weed control products are among the most widely used broad-spectrum herbicides in the world. The herbicidal properties of glyphosate were discovered in 1970, and commercial formulations for nonselective weed control were first introduced in 1974 (Franz et al. 1997). Formulations of glyphosate, including Roundup® Herbicide (RU)1 (Monsanto Company, St. Louis, MO), have been extensively investigated for their potential to produce adverse effects in nontarget organisms. Governmental regulatory agencies, international organizations, and others have reviewed and assessed the available scientific data for glyphosate formulations and independently judged their safety. Conclusions from three major organizations are publicly available and indicate RU can be used with minimal risk to the environment (Agriculture Canada 1991; USEPA 1993a; WHO 1994). Several review publications are available on the fate and effects of RU or glyphosate in the environment (Carlisle and Trevors 1988;Smith and Oehme 1992 ; Malik et al. 1989;Rueppel et al. 1977; Sullivan and Sullivan 1997;Forestry Canada, 1989). In addition, several books have been published about the environmental and human health considerations of glyphosate and its formulations (Grossbard and Atkinson 1985; Franz et al. 1997). In addition, RU and other glyphosate formulations have been selected for use in a number of weed control programs for state and local jurisdictions in the United States. Many of these uses require that ecological risk assessments be conducted in the form of Environmental Impact Statements or Environmental Assessments. These documents are comprehensive and specific to local use situations. Documents are available for risk assessments in Texas, Washington, Oregon, Pennsylvania, New York, Virginia, and other states (USDA 1989;USDA 1992;USDA 1996;USDA 1997;USDI 1989; Washington State DOT 1993).
883 citations
TL;DR: The literature on pesticide losses in runoff waters from agricultural fields is reviewed in this paper, where the majority of commercial pesticides, total losses are 0.5%0 or less of the amounts applied, unless severe rainfall conditions occur within 1-2 weeks after application.
Abstract: The literature on pesticide losses in runoff waters from agricultural fields is reviewed. For the majority of commercial pesticides, total losses are 0.5%0 or less of the amounts applied, unless severe rainfall conditions occur within 1–2 weeks after application. Exceptions are the organochlorine insecticides, which may lose about 1% regardless of weather pattern because of their long persistence; and soil surface-applied, wettable-powder formulations of herbicides, which may lose up to 5%, depending on weather and slope, because of the ease of washoff of the powder.Pesticides with solubilities of 10 ppm or higher are lost mainly in the water phase of runoff, and erosion control practices will have little effect on such losses. Organochlorine pesticides, paraquat, and arsenical pesticides, however, are important cases of pesticides which are strongly adsorbed by sediments, and erosion control can be important in controlling losses of these compounds.The behavior and fate of pesticides in streams receiving runoff is generally not known. Information on such factors as time and distance of impact of a given runoff event, ability of local ecosystems to recover from transient pesticide concentrations, and dissipation or concentration processes in aquatic ecosystems will have to be obtained before “edge-of-field” pesticide losses can be related to water quality in receiving waters.
753 citations
TL;DR: Glyphosate [N-(phosphonomethyl)glycine] was readily bound to kaolinite, illite, and bentonite clay and to charcoal and muck but not to ethyl cellulose as mentioned in this paper.
Abstract: Glyphosate [N-(phosphonomethyl)glycine] was readily bound to kaolinite, illite, and bentonite clay and to charcoal and muck but not to ethyl cellulose. Fe+++ and Al+++-saturated clays and organic matter adsorbed more glyphosate than Na+ or Ca+-saturated clays and organic matter. Glyphosate appears to be bound to the soil through the phosphonic acid moiety as phosphate in the soil competed with 14C-glyphosate for adsorption sites. Glyphosate mobility in the soil was very limited and was affected by pH, phosphate level, and soil type. The 14C-glyphosate was biodegraded in soil to 14CO2 possibly by co-metabolism. Potentiometric titrations of the compound gave pKa values of 2, 2.6, 5.6, and 10.6.
444 citations
TL;DR: Glyphosate-resistant crops have promoted the adoption of reduced- or no-tillage agriculture in the USA and Argentina, providing a substantial environmental benefit and the development and use of failsafe introgression barriers in crops with such linked genes is needed.
Abstract: Glyphosate [N-(phosphonomethyl) glycine]-resistant crops (GRCs), canola (Brassica napus L.), cotton (Gossypium hirsutum L.), maize (Zea mays L.), and soybean [Glycine max (L.) Merr.] have been commercialized and grown extensively in the Western Hemisphere and, to a lesser extent, elsewhere. Glyphosate-resistant cotton and soybean have become dominant in those countries where their planting is permitted. Effects of glyphosate on contamination of soil, water, and air are minimal, compared to some of the herbicides that they replace. No risks have been found with food or feed safety or nutritional value in products from currently available GRCs. Glyphosate-resistant crops have promoted the adoption of reduced- or no-tillage agriculture in the USA and Argentina, providing a substantial environmental benefit. Weed species in GRC fields have shifted to those that can more successfully withstand glyphosate and to those that avoid the time of its application. Three weed species have evolved resistance to glyphosate in GRCs. Glyphosate-resistant crops have greater potential to become problems as volunteer crops than do conventional crops. Glyphosate resistance transgenes have been found in fields of canola that are supposed to be non-transgenic. Under some circumstances, the largest risk of GRCs may be transgene flow (introgression) from GRCs to related species that might become problems in natural ecosystems. Glyphosate resistance transgenes themselves are highly unlikely to be a risk in wild plant populations, but when linked to transgenes that may impart fitness benefits outside of agriculture (e.g., insect resistance), natural ecosystems could be affected. The development and use of failsafe introgression barriers in crops with such linked genes is needed.
387 citations
TL;DR: In this paper, the Soil and Water Assessment Tool (SWAT) water quality model is designed to assess nonpoint and point source pollution and was recently modified for tile drainage.
Abstract: The presence of subsurface tile drainage systems can facilitate nutrient and pesticide transport, thereby contributing to environmental pollution. The Soil and Water Assessment Tool (SWAT) water quality model is designed to assess nonpoint and point source pollution and was recently modified for tile drainage. Over 25% of the nation's cropland required improved drainage. In this study, the model's ability to validate the tile drainage component is evaluated with nine years of hydrologic monitoring data collected from the South Fork watershed in Iowa, since about 80% of this watershed is tile drained. This watershed is a Conservation Effects Assessment Program benchmark watershed and typifies one of the more intensively managed agricultural areas in the Midwest. Comparison of measured and predicted values demonstrated that inclusion of the tile drainage system is imperative for obtaining a realistic watershed water balance. Two calibration/validation scenarios tested if the results differed in how the data set was divided. The optimum scenario results for the simulated monthly and daily flows had Nash-Sutcliffe efficiency (ENS) values during the calibration/validation (1995-1998/1999-2004) periods of 0.9/0.7 and 0.5/0.4, respectively. The second scenario results for the simulated monthly and daily flows had ENS values during the calibration/validation (1995-2000/2001-2004) periods of 0.8/0.5 and 0.7/0.2, respectively. The optimum scenario reflects the distribution of peak rainfall events represented in both the calibration and validation periods. The year 2000, being extremely dry, negatively impacted both the calibration and validation results. Each water budget component of the model gave reasonable output, which reveals that this model can be used for the assessment of tile drainage with its associated practices. Water yield results were significantly different for the simulations with and without the tile flow component (25.1% and 16.9%, expressed as a percent of precipitation). The results suggest that the SWAT2005 version modified for tile drainage is a promising tool to evaluate streamflow in tile-drained regions when the calibration period contains streamflows representing a wide range of rainfall events.
209 citations