First records of polycyclic aromatic hydrocarbons and metals in sediments from a shallow lake in the Pampean-Patagonian region (Argentina)

Abstract

This study evaluated, for the first time, organic and metal contaminants in sediments from Argentinean saline lakes, specifically La Salada shallow lake, a small polymictic lake on the south border of the Pampean region. The concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) and 8 metals (Cd, Cu, Cr, Fe, Mn, Ni, Pb and Zn) was assessed and the ecotoxicological effects of these pollutants were examined. The total concentration of the 16 PAHs ranged from 12.55 to 10 679.48 ng g-1 dry weight, with a predominance of four-ringed PAHs. Molecular ratio analysis showed pyrolytic sources as the main source of PAHs. Among the metals, Mn, Fe and Zn had the highest concentrations in sediments. General metal levels revealed a multiplicity of point sources and rock weathering as their main source. Regarding the potential ecotoxicological effects, adverse effects may be expected from PAHs because several compounds exceeded the sediment quality guidelines threshold effect level and likely effect level. Conversely, metal levels were below levels specified in safety guidelines. These results are interpreted in an international context, providing information that addresses a gap in the pollution record of Argentinean lakes, and should have strong implications for future planning management.