PERSISTENT ORGANIC COMPOUNDS AND WATER STABLES ISOTOPES IN RAIN OF BUENOS AIRES CITY, ARGENTINA

MIGLIORANZA KARINA SILVIA BEATRIZ; SHIMABUKURO VALERIA; MARTINEZ DANIEL; DAPEÑA CRISTINA

Simposio; International Symposium on Isotope Hydrology; 2019

Persistent organic pollutants (POPs) are persistent, ubiquitous and hydrophobic compounds with chronic toxicity, including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Due to their characteristics and volatility can be found in biotic and abiotic matrices and be transported with air masses reaching distant regions through dry or wet depositions (rains). The relationship between the isotope composition of 18O and 2H in the precipitation and the different "effects" that determine the variations in the isotopic composition of the rain from the water vapor masses, could help to understand the processes of POPs drag atmospheric with precipitation. The objective of this study was to know the concentration of POPs in the rainwater Buenos Aires city, as a potential source of contamination of groundwater mainly through the losses in rainwater networks, and analyze using isotopic tracers possible conditions of incorporation of these pollutants to the rains. The rain samples were collected throughout the year 2015-2016 in 8 sampling sites. The OCPs (endosulfans, DDTs, HCHs, chlordanes, heptachlor and aldrins) were analyzed by gas chromatography with electron capture detector. The isotopic analyzes were carried out by laser spectroscopy using a "DLT-100 Liquid-Water Isotope Analyzer" automated injection developed by "Los Gatos Research". The results were expressed as isotopic deviations in values per thousand (?): δ = 1,000 (Rs-Rp) / Rp ?, where δ: isotopic deviation in ?, s: sample, p: international reference and R: isotopic ratio (2H/1H, 18O/16O).The highest concentrations of pollutants were found at the end of summer in the area of Liniers (24.8 ug/L) followed by Mataderos (1.85 ug/L). The endosulfans was the most important pesticide group in all areas, followed by PCBs in the stations of Liniers, Mataderos and Pilar. The total concentrations of pesticides vs. δ18O (Fig. 4) showed a slight tendency to increase towards the more isotopically enriched samples. The impact of agriculture and the urban/industrial areas itself in the wet deposition, alerts to the inputs of pollutants into the aquifer in urban areas, especially due to losses in rainwater drainage networks.