SPATIAL AND TEMPORAL TRENDS AND FLOW DYNAMICS OF GLYPHOSATE AND OTHER PESTICIDES WITHIN AN AGRICULTURAL WATERSHED IN ARGENTINA

PEREZ, DÉBORA J.; OKADA, ELENA; DE GERÓNIMO, EDUARDO; MENONE, MIRTA L.; APARICIO, VIRGINIA C.; COSTA, JOSÉ L.

ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY

SETAC PRESS

Año: 2017

0730-7268

In the present study, we evaluated the spatial and temporal trends of current use pesticides in surface water and sediments and to determine its relation with hydrological stream dynamics within the agricultural watershed of El Crespo stream. We sampled two contrasting sites: Site 1 (upstream) surrounded by agricultural lands, and Site 2 (downstream) surrounded by natural grasslands. Most of the applied pesticides (i.e. glyphosate, 2,4-D, atrazine,tebuconazole and imidacloprid) were detected in high frequencies in surface water samples at both sites. However, only glyphosate and AMPA (aminomethylphosphonic acid) were present at high concentrations and had a significant spatial-temporal trend. The highest concentrations were found during spring 2014 in 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, since glyphosate was the most applied herbicide during the fallow period in 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 that influenced the stream hydrology and pesticide behavior at El Crespo watershed. The estimated annual pesticide losses were 3.11 g/ha in Site 1 and 0.72 g/ha in Site 2. This result indicates that possible attenuation process could be decreasing the pesticides loads during the downstream transport from Site 1 to Site 2.