Natural and Anthropogenic Input of Heavy Metals in Sediments from Bahía Blanca Estuary (Argentina)

GRECCO, L.E.; MARCOS, A.O.; GÓMEZ, E.A.; BOTTÉ, S.E.; MARCOVECCHIO, J.E.

JOURNAL OF COASTAL RESEARCH

Coastal Education & Research Foundation, Inc. (CERF)

Lugar: West Palm Beach, Florida, USA; Año: 2006 vol. SI39 p. 1021 - 1025

0749-0208

The geochemistry, mineralogy and grain size distribution of several estuarine sediment samples from potentially man-influenced areas and zones without such influence were analyzed to determine the natural heavy metal content in order to evaluate the man-originated impact into the Bahía Blanca estuarine environment. It is determined that with the exception of those places where untreated sewage outfall occurs, a direct  relationship between the percentage of the clay size fraction (<2 m) and the total heavy metals content happens. The total heavy metal contents were under the established hazardous levels in all the analyzed samples. Nevertheless, those potentially man-influenced areas (harbors, industries, cities) show highest, total concentration values as well as percentages of bioavailable fractions, which would evidence a low and not extensive anthropogenic input into the environment. The relative high proportion in which Cd, Pb and Cr appear as bioavailable compounds at some sites not-influenced by human activities, suggest the existence of a natural source of these elements. This could be attributed to the weathering of naturally occurring volcanic minerals, indicating that a special care should be taken when sediment monitoring in relation to anthropogenic activity are carried out within this estuarine environment.