Historical mercury trends recorded in sediments from the Laguna del Plata, Córdoba, Argentina

STUPAR, Y.; SCHÄFER, J; GARCÍA M. G; SCHMIDT S; PIOVANO, E.; BLANC, G; HUNEAU F.; LE COUSTUMER PH

CHEMIE DER ERDE

ELSEVIER GMBH, URBAN & FISCHER VERLAG

Lugar: ALEMANIA; Año: 2014 vol. 74 p. 353 - 363

0009-2819

The main carrying phases of mercury (Hg) were analyzed in a 120 cm sediment core taken at the Laguna del Plata (LP), a small lake connected to the main water body of Laguna Mar Chiquita (LMC) during highstands. LMC is considered to be one of the largest saline lakes in the world representing a sensitive climatic indicator due to its frequent lake level variations at millennial and interdecadal scale like the last ones that started early in the 1970s and after 2004. Total Particulate Hg (HgTP) concentrations vary between ~13 and ~131 µg kg-1 indicating a system with low pollution. Selective extractions with ascorbate, HCl and H2O2 were performed in the sediments and they revealed that Hg is associated mainly to reactive sulfides in the base of the core, while in the middle and upper part the organic matter seems to be the main Hg-bearing phase. The highest and most important peak was found in sediments accumulated between 1991 and 1995. More than a punctual source of pollution, this peak is likely related to two eruptive events occurred in the Andean Cordillera in this period: the erupcion of Hudson volcano in southern Patagonia that occurred in 1991 and the one of the Lascar volcano in northern Chile that occurred in 1993. In both cases, the respective ash plumes were documented to have reached the Laguna del Plata region