Article

Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins

US Geological Survey, Pearl, MS, USA.
Pest Management Science (Impact Factor: 2.74). 01/2012; 68(1):16-30. DOI: 10.1002/ps.2212
Source: PubMed

ABSTRACT 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.
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.
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.

4 Followers
 · 
299 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Organic phosphorus can be one of the major fractions of phosphorus in many aquatic ecosystems. Unfortunately, in many studies the ‘organic’ P fraction is operationally defined. In solution, organic P is often defined simply as the difference between reactive P and total P; in sediments it has been defined as the P remaining at the end of a sequential extraction scheme. However, there are an increasing number of studies where the organic P species have been structurally characterised – in part because of the adoption of 31P nuclear magnetic resonance spectroscopic techniques. There are five classes of organic P species that have been relatively well characterised in the aquatic environment – nucleic acids, other nucleotides, inositol phosphates, phospholipids and phosphonates. This paper explores the identification, quantification, biogeochemical cycling and ecological significance of these five classes of organic P compounds. Based on what is known about these five classes of organic P compounds in the environment this paper sets out a number of principles which could guide the research of organic P into the future. There is an ongoing need to develop need to develop methods for quickly and accurately identifying and quantifying organic P species in the environment. The types of ecosystems in which organic P dynamics are studied needs to be expanded; flowing waters, floodplains and small wetlands are currently all under-represented in the literature. While enzymatic hydrolysis is an important transformation pathway for the breakdown of organic P, more effort needs to be directed towards studying other potential transformation pathways. Similarly effort should be directed to estimating the rates of transformations, not simply reporting on the concentrations. And finally, further work is needed in elucidating other roles of organic P in the environment other than simply a source of P to aquatic organisms.
    Environmental Chemistry 01/2013; 10(6):439-454. DOI:10.1071/EN13151 · 3.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An enzyme-linked immunosorbent assay (ELISA) for the detection of glyphosate was investigated for assay performance characteristics and was applied for determination of glyphosate contamination levels in selected surface and ground water resources in Hungary in 2010 and 2011. Advantages of the method include its simplicity (no laborious extraction) and specificity (cross-reactivity is below 0.1% for related compounds, e.g. aminomethyl-phosphonic acid, glufosinate). On the basis of our experiments, the practical limit of detection (LOD) ranged between 0.05 and 0.12 ng/ml. The standard curve was of sigmoid (logistic) characteristics, and it co-occurred with curves obtained for spiked surface water samples. Matrix effects were observed in tap water, possibly due to chlorination and/or heavy metal ions, e.g. copper and zinc. The method was applied for the analysis of 42 surface and ground water samples collected from Békés county in Hungary at 14 sampling sites in 2010 and 18 surface water samples collected from the Danube River and Lake Velencei in Hungary at 12 sampling sites in 2011. Exceedingly high glyphosate levels (nearly 1 ng/ml) were measured in 5 samples, and significant concentrations were determined in 16 cases (0.54–0.76 ng/ml) in 2010, while practically no contamination was found in 2011. The great contrast between the two sampling regimes is explained by differing agricultural locations, natural precipitation and, to a greater extent, catchment area characteristics, resulting in varying leaching or run-off of glyphosate to surface waters.
    Microchemical Journal 03/2013; 107:143-151. DOI:10.1016/j.microc.2012.05.021 · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Repeated applications of glyphosate may contaminate the soil and water and threaten their quality both within the environmental system and beyond it through water erosion related processes and leaching. In this study, we focused on the transport of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) related to soil erosion at two slope gradients (10 and 20°), two rates of pesticide with a formulation of glyphosate (Roundup®) application (360 and 720 mg m− 2), and a rain intensity of 1.0 mm min− 1 for 1 h on bare soil in hydraulic flumes. Runoff and erosion rate were significantly different within slope gradients (p < 0.05) while suspended load concentration was relatively constant after 15 min of rainfall. The glyphosate and AMPA concentration in the runoff and suspended load gradually decreased. Significant power and exponent function relationship were observed between rainfall duration and the concentration of glyphosate and AMPA (p < 0.01) in runoff and suspended load, respectively. Meanwhile, glyphosate and AMPA content in the eroded material depended more on the initial rate of application than on the slope gradients. The transport rate of glyphosate by runoff and suspended load was approximately 14% of the applied amount, and the chemicals were mainly transported in the suspended load. The glyphosate and AMPA content in the flume soil at the end of the experiment decreased significantly with depth (p < 0.05), and approximately 72, 2, and 3% of the applied glyphosate (including AMPA) remained in the 0–2, 2–5, and 5–10 cm soil layers, respectively. The risk of contamination in deep soil and the groundwater was thus low, but 5% of the initial application did reach the 2–10 cm soil layer. The risk of contamination of surface water through runoff and sedimentation, however, can be considerable, especially in regions where rain-induced soil erosion is common.
    Science of The Total Environment 04/2015; 512. DOI:10.1016/j.scitotenv.2015.01.071 · 3.16 Impact Factor

Preview

Download
23 Downloads
Available from