CONICET | Buscador de Institutos y Recursos Humanos

Water monitoring is of great importance, especially for waterbodies in agricultural or industrialareas. Grab sampling is a widely used technique for aquatic monitoring but represents only asnapshot of the contaminant levels at a specific point in time. Passive sampling, on the otherhand, is an integrative technique which provides an average concentration of contaminantsrepresentative for its deployment period. Thus, the current contamination by organochlorinepesticides (OCPs), polychlorinated biphenyls (PCBs) and some currently used pesticides(CUPs) was assessed along the Quequén Grande River watershed using the integrative siliconerubber (SR) passive sampling technique in a year-long study. SR samplers were deployed at sixsampling sites selected according to different land uses (agricultural-livestock production,agricultural and urban activities) during three periods in 2014 and 2015. OCPs were dominatedby endosulfan (sum of α-, β-endosulfan, endosulfan sulfate = 0.15-23.4 ng/L). The highestendosulfan levels were registered during the pesticide application period (December?March),exceeding the international water quality guidelines for protecting freshwater biota (3 ng/L).Comparing with previous reports, no reduction in endosulfan levels were observed at theQuequén Grande River watershed. These results would suggest the illegal use of remainingstocks since water sampling was carried out after endosulfan ban in Argentina. Chlorpyrifoswas the second major pesticide found in water (0.02-4.3 ng/L), associated with its widespreadusage on soybean crops. A reduction in levels of legacy pesticides (heptachlors, DDTs, dieldrinand chlordanes) was evident when compared with previous reports from 2007. PCBs levelswere very low indicating that probably only minor diffuse sources were still available along theQuequén Grande River watershed.

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