Screening of pesticide in surface waters of four basin of the Pampas Region of Argentina with different degree of agriculture intensities.

MARINO, D.J.; ELORRIAGA, Y.; APARICIO, V.; CARRIQUIRIBORDE, P.

Congreso; SETAC- North America 32th Annual Meeting; 2012

Society of Environmental Toxicology and Chemistry

The Pampas Region is the main agricultural district of Argentina predominantly by the alternated production of soybean and corn in summer and wheat in winter. Despite the wide spread of this activity little is known of its impact on surface water quality and the aquatic ecosystems at the regional scale. In this study, 70 pesticides were determined in surface water samples from 22 sites distributed along four agriculture basins, two mainly agricultural and two mostly extensive livestock. Samples were filtered through 0.45 µm GF/F immediately after collection and transported in glass bottles to the laboratory. SPE extraction was performed with C18 OASIS HLB, within the 48h after collection. Pesticide analysis was performed by UPLC-MS/MS ESI(+/-) (Aqcuity-Quattro Premier). Spiking and isotopic dilution methods were used for quality assurance. A total of 35 samples were analyzed. Among all the pesticides measured, only 30 were positively detected. Conversely to the expected, patterns in the composition of detected pesticides were similar in both classes of basins, only four pesticides were not observed in the less agricultural basins. On the other hand, clear differences were observed in the abundance. Differences in the frequency of occurrence of some pesticides were observed when comparing summer and winter samplings (i.e. atrazine was 100% detected in summer and 90% in winter and metsulfuron methyl 60% in winter and not detected in summer). In addition, during the summer triazole fungicides and agricultural pyrethroids were detected in the 80% and 70% of the samples, respectively. Finally, imidazolinone herbicides were detected in the 20% of the cases. In the present study a broad screening of pesticides at regional scale was performed in the Argentinean Pampas, revealing for the first time the occurrence of a wide number of pesticides together with characteristic spatial and temporal patterns.