Heavy metal inputs in Northern Patagonia lakes from short sediment core analysis

Heavy metal profiles of short sediment cores sampled from lakes located in Nahuel Huapi National Park, Northern Patagonia, Argentina, were determined by INAA. Core dating was performed by measuring natural Pb-210 and anthropogenic Cs-137, and by identification of tephra layers. No evidence was found for the input increase of the trace elements Sb, Ba, Cs, Zn, Co, Hf, Ni, Se, Sr, Ti, U, and V in the lake environment. High As concentrations (up to 250 mu g center dot g(-1)) were found in relation with the diffusion processes of Mn and Fe oxides. Strong correlation was observed between the Br concentration and organic matter content, but no evidence was found for the relevant increase of Br inputs in recent years. Ag concentrations were found to be enriched in the upper core layers over the baseline values determined for deep layers ranging from 0.1 to 0.2 mu g center dot g(-1). Hg concentration profiles were also enriched in the upper core layers over the baseline (from less than 0.07 to 0.2 mu g center dot g(-1) for pre-industrial time, to 0.1 to 0.3 mu g center dot g(-1) for modern times) but in relation with the increased organic matter content of the sediment.