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In the present study, we evaluated the spatial and temporal trends of current-use pesticides in surface water and sediments as well as their relationship with hydrological stream dynamics within the agricultural watershed of El Crespo stream (Buenos Aires Province, Argentina). We sampled 2 contrasting sites: site 1 (upstream), surrounded by agricultural lands, and site 2 (downstream), surrounded by natural grasslands. Most of the applied pesticides (glyphosate, 2,4-D, atrazine, tebuconazole, and imidacloprid) were detected at high frequencies in surface water samples at both sites. However, only glyphosate and aminomethylphosphonic acid (AMPA) were present at high concentrations and had a significant spatial-temporal trend. The highest concentrations were found during spring 2014 at site 1, in association with the intense rains that occurred in that season. The fact that glyphosate and AMPA concentrations were higher than the rest of the studied compounds is closely related to the land use within the watershed, as glyphosate was the most applied herbicide during the fallow period of glyphosate-resistant crops (soybean, maize). The pesticide mixture had a significant spatial-temporal trend, reaching the highest levels during storm flow events in spring 2014. The intensive rains in spring 2014 could be the main factor influencing stream hydrology and pesticide behavior at El Crespo watershed. The estimated annual pesticide losses were 3.11 g/ha at site 1 and 0.72 g/ha at site 2. This result indicates that an attenuation process could be decreasing pesticide loads during downstream transport from site 1 to site 2. Environ Toxicol Chem 2017;36:3206-3216. © 2017 SETAC., (© 2017 SETAC.)

Argentina has 31 million hectares given over to agriculture comprising 2.2% of the world's total area under cultivation (Stock Exchange of Rosario, Argentina). Despite the intensity of this agricultural activity, data on pesticide pollution in surface water are rather scarce. In this sense, the aim of this work is to determine the presence of pesticides in surface water of four agricultural sub-basins of Argentine. An environmental monitoring was carried out to determine the impact of twenty-nine pesticides used in agricultural activities on the surface water quality of agricultural areas within the San Vicente, Azul, Buenos Aires southeast and Mista stream sub-basins. The samples were analyzed by solid-phase extraction (SPE) using OASIS HLB 60 mg cartridges and ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC/MSMS) that provided good analytical quality parameters. The southeast of Buenos Aires was the site with the highest frequency of pesticides detection, followed by Azul and San Vicente microbasins. The most detected pesticides, considering all surface water samples, were atrazine, tebuconazole and diethyltoluamide with maximum concentration levels of 1.4, 0.035, and 0.701 μg L(-1), respectively. The results obtained for all basins studied show the presence of residual pesticides in surface waters according the different agricultural activities developed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Retention is one of the processes controlling the behavior and fate of pesticides in soil. The objective of this work was to evaluate the adsorption and desorption of glyphosate, AMPA, and metsulfuron-methyl in the main horizons of a Typic Argiudoll destined for agricultural use. For this purpose, the batch equilibrium method was used at a range of concentrations for each compound. Desorption was performed in three consecutive steps after the adsorption experiment. The results obtained showed strong adsorption of glyphosate and AMPA in the three horizons, following the trend B > A > C, with weak desorption. Metsulfuron-methyl, on the other hand, showed weak adsorption in the three horizons, following the trend A > B > C, with relevant desorption. Our results allow us to identify metsulfuron-methyl as the compound that poses the greatest environmental risk in terms of the potential contamination of other areas and groundwater. However, despite their strong adsorption and weak desorption, glyphosate and AMPA also represent potential contaminants of other environmental matrices. [ABSTRACT FROM AUTHOR]

• Glyphosate and AMPA were analyzed in aggregates, and respirable dust (RD) emitted by aggregates. • Finer aggregates showed higher glyphosate and AMPA concentrations than coarser aggregates. • Glyphosate content in the RD was directly related to glyphosate content in the aggregate. • Glyphosate and AMPA concentrations in the RD were higher than in aggregates. The objective of this study was to analyze glyphosate- and aminomethylphosphonic acid (AMPA) concentrations in the respirable dust (RD) emitted by different soil aggregates, shortly after herbicide application in a field approach. The relationships of both glyphosate and AMPA in the aggregates with organic matter- (OM), total iron- (Fe), and extractable phosphorus contents (P) as well as with pH CaCl2 values were analyzed. An Kastanozem haplic of the Semiarid Pampas (Argentina) was analyzed 7 days after glyphosate application. The RD (particulate matter <10 mm in diameter, PM10) was generated and collected for the following aggregate-size fractions: <0.42 mm, 0.42 to 0.84 mm, 0.84 to 2 mm, 2 to 6.4 mm, 6.4 to 19.2 mm, and >19.2 mm. OM, P, Fe and pH CaCl2 were analyzed in the aggregate fractions, and glyphosate- and AMPA contents were measured both in RD and in the aggregate fractions. Glyphosate concentration varied between 16 mg kg−1 (aggregates <0.42 mm) and 4.7 mg kg−1 (aggregates >19.2 mm) and increased with decreasing size of the aggregates. Glyphosate concentration in RD varied between 48.5 mg kg−1 (aggregates <0.42 mm) and 17.8 mg kg−1 (aggregates >19.2 mm). Finest aggregates emitted RD with higher glyphosate concentrations. A positive relationship was determined between glyphosate in aggregates and glyphosate in RD (p < 0.05), indicating that aggregates with higher glyphosate concentration emitted a more glyphosate-enriched RD. Glyphosate in the aggregate fractions was not related to Fe, OM or pH of aggregates. Glyphosate- and P concentrations in aggregates were positively correlated. This is explained because both substances share a phosphonic acid functional group and they have similar reactivities in the soil. AMPA concentration varied between 130 mg kg−1 (aggregates >19.2 mm) and 307 mg kg−1 (aggregates <0.42 mm) in aggregates and between 527 ug kg−1 and 746 ug kg−1 in RD. AMPA concentrations in RD were not related to AMPA concentrations in aggregates. The contents of AMPA were higher than those of glyphosate in both, RD and aggregates, due to the longer persistence of AMPA in relation to glyphosate. In all cases, glyphosate- and AMPA concentrations were higher in RD than in the aggregates. Our results suggest that the RD emitted by agricultural soils has higher glyphosate- and AMPA concentrations than the bulk soil. These results encourage future investigations to elucidate if other pesticides (and the surfactants used in their formulations) are present in the RD emitted by agricultural soils. This information is necessary in order to evaluate the effects of the particulate matter emitted by agricultural soils on the whole ecosystem and the human health. [ABSTRACT FROM AUTHOR]