SAUCE CHICO RIVER AND NAPOSTA' GRANDE CREEK AS A POTENTIAL SOURCE OF HEAVY METALS TO BAHR BLANCA ESTUARY

DEL BLANCO, LILIANA; BOTTÉ, SANDRA; CHIARELLO, NEDDA; ARLENGHI, JAVIER; ASTEASUAIN, RAÚL; FREIJE, HUGO; MARCOVECCHIO, JORGE

Buzios

Simposio; 4th International Symposium Environmental Geochemistry In Tropical Countries; 2004

Universidad de Brasil

Sauce Chico river and the Naposta Grande stream are the most important natural tributaries to Bahia Blanca coastal system. It is 4th International Symposium Environmental Geochemistry In Tropical Countries Sources, transport and fate of chemicals interesting to remark that the Naposto Grande stream Is the unique natural water flow crossing through Bahia Blanca city, and flowing toward the estuary. In order to characterize the metal transport through the tributaries to the estuary, as much in its dissolved forms as in the bound to the suspended material ones, and the possible environmental Impact that they suffer by the anthropic activity, a study of the heavy metal concentrations was made in waters and surface sediments of Sauce Chico river and Naposta Grande stream. Samples of water and surface sediments from Naposta Grande Stream, after crossing the city of Bahia Blanca, and from Sauce Chico River were monthly collected from March 2002 to May 2003. The dissolved metals were extracted by chelation with ammonium pyrrolidine-dithiocarbamate (APDC) followed by extraction into metil iso-butil ketone (MIBK) according to a modification of the method described by Koirtyohann & Wert Sediments were digested in a mixture of concentrated nitric and perchloric acids, according to the method modified by Marcovecchio et al. Heavy metals (Cu, Zn, Cd, Pb, Cr, Ni, Mn and Fe) were measured by flame atomic absorption spectrometry. The obtained results have allowed to present a preliminary masses balance for this environment, and suggested that in this study area, metals concentrations are comparable with those measured in pristine rivers and non contaminated seawater and both water flows contribution magnitudes were similar.