Registro histórico de mercurio en la cuenca del río Suquía, Córdoba

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

Procesos geoquímicos superficiales en Iberoamérica.

Sociedad Iberoamericana de Física y Química Ambiental

Lugar: Salamanca; Año: 2014; p. 303 - 324

Exchange at the air-water interface and atmospheric mobilization are important features in the global mercury cycle. Sediments can represent efficient Hg traps and archives of past contamination and act as secondary sources, releasing Hg again into solution under suitable environmental conditions. The aim of this work is to characterize mercury concentrations determined in present riverbed sediments and Laguna del Plata and Mar Chiquita Lakes bottom sediments (Argentina). The historical record of this element was performed in the Laguna del Plata sediment core, where Suquía river mouths. Total particulate mercury (HgTp) was analyzed by cold vapour atomic absorption spectrometry and the measures threw values between 2-131 μg/kg. It was observed that total Hg concentrations are ~7 times higher in the silty fraction of the sediments than in the sandy one. The higher concentrations are located in the basin headwater rivers where it is possible to find metallic sulphur in mineralised veins, therefore it is expected that these minerasl are carried downstream during rocks weathering and accumulated in the San Roque dam and rivers that start in it. On the sediment core the higher total particulate Hg concentrations are registered in the periods with maximum lake levels, which has a close relationship with the actual transport model. According to the actual hydrological dynamics, in rainy periods, sediment transport from the basin headwaters is higher. Under these conditions, Hg reaches the lake probably adsorbed onto Fe and Mn (hydr)oxides, and released to the solution as a consequence of the high water salinity. In more arid periods, the released Hg could have been incorporated to the sediments as co-precipitated with carbonates or adsorbed, while in more humid periods the higher biological activity in the lake favours Hg association with organic