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: Investigation of the dissipation and transport of the herbicides, glyphosate and glufosinate, in soil used for the transgenic production of canola and a comparison was made with the herbicide, trifluralin, used in non-transgenic canola found it to be the least persistent herbicide.
10 citations
TL;DR: Persistent nonlethal doses of glyphosate in plant tissue may have implications for the edible and (or) medicinal use of native plants.
Abstract: Persistent nonlethal doses of glyphosate in plant tissue may have implications for the edible and (or) medicinal use of native plants. This study investigated native plants growing in northern Brit...
10 citations
TL;DR: In this paper, two simple and environmentally friendly methods based on enzymatic inhibition for the rapid determination of glyphosate in commercial formulations were compared, and the principle of the methods is bas...
Abstract: Two simple and environmentally friendly methods based on enzymatic inhibition for the rapid determination of glyphosate in commercial formulations were compared. The principle of the methods is bas...
10 citations
01 Mar 2021
TL;DR: In this paper, the authors evaluated types of herbicides used, assessed the perceptions of the effects of herbicide usage among farmers enrolled in a taungya (i.e. farm forestry programs) in the dry semi-deciduous ecological zone of Ghana, and determined the impact of socioeconomic factors that influence farmers decision to use herbicides on farms.
Abstract: Although herbicides have extensively been used in forest landscape restoration, its effects and opportunity costs have rarely been studied in Ghana. This study evaluated types of herbicides used, assessed the perceptions of the effects of herbicide usage among farmers enrolled in a taungya (i.e. farm forestry programs) in the dry semi-deciduous ecological zone of Ghana. The study also analyzed the challenges associated with the application of herbicides and determined the impact of socio-economic factors that influence farmers decision to use herbicides on farms. Data were collected from 300 taungya farmers and 20 herbicide traders in Offinso North, Offinso South, and Techiman South Municipal. Data collection was completed in December 2016. Data were analyzed descriptively and quantitatively. Results indicate that 100% of farmers perceived herbicides as having deleterious effects on flora (seedlings, under-storey wild foods, medicines) and fauna (soil micro-organisms, fish in rivers) as well as water quality, soil structure and human health. Nevertheless, 93% of them use herbicides to reduce labour costs and to establish larger acreages. Based on their functional properties, 85% of herbicides traded are non-selective for bush clearing and 15% are selective for weeding. Farmers use them indiscriminately due to poor knowledge on recommended practices and intensity of invasiveness of weed species. Education, residential status and age of respondents significantly predicted usage. The study recommends a review of Ghana's pesticide deployment strategies and herbicides guide book for use in farm forestry. Capacity of frontline forestry professionals, traders and farmer-based organizations must be enhanced to effectively advice and monitor safe application. Plant based herbicides must be promoted for safety and enhancement of biodiversity.
10 citations
TL;DR: The increased feeding activity when exposed to Roundup® in combination with an unchanged ETS activity suggests effects on the metabolic efficiency of G. fossarum, and it is argued that Roundup® enhances the anabolic activity (feeding activity) in order to maintain the catabolicactivity (ETS activity).
Abstract: Pesticides can easily reach surface waters via runoff and their potential to have detrimental impacts on freshwater organisms is high Not much is known about how macroinvertebrates react to glyphosate contamination In this study we investigated lethal and sublethal effects of the exposure of Gammarus fossarum to Roundup®, a glyphosate-based herbicide The LC10 and LC50 values after 96 h were determined to be 065 ml/L Roundup® (230 mg/L glyphosate) and 096 ml/L Roundup® (340 mg/L glyphosate), respectively As a sublethal measure of toxicity we conducted eight experiments with the feeding activity and the respiratory electron transport system (ETS) activity as endpoints All experiments lasted seven days Although the LC10 concentration of Roundup® was used for the feeding activity tests, 49% of the gammarids died before the end of the experiments, which is inconsistent with the calculated LC10-values The feeding activity was significantly higher in Roundup®-enriched water (mean = 018 mg/mg x d) in comparison to pure spring water (mean = 0079 mg/mg x d) No significant difference was observed between the ETS activity, which was determined after 24, 48 or 96 h after the start of the experiment, of the gammarids in Roundup® solution and in the control The LC-values determined here are rather high, and exceed background glyphosate concentrations in most anthropogenically influenced surface waters The increased feeding activity when exposed to Roundup® in combination with an unchanged ETS activity suggests effects on the metabolic efficiency of G fossarum We argue that Roundup® enhances the anabolic activity (feeding activity) in order to maintain the catabolic activity (ETS activity)
9 citations
Cites background from "Fate and transport of glyphosate an..."
...Coupe et al. (2012) sampled streams during a storm event and measured glyphosate concentrations of 430 μg/L glyphosate....
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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