Geochemical control of heavy metal concentrations and distributions within Bahia Blanca estuary (Argentina)

MARCOVECCHIO JORGE; BOTTÉ SANDRA; FERNÁNDEZ SEVERINI MELISA; DELUCCHI FEDERICO

Aquatic Geochemistry

Springer

Lugar: Netherlands; Año: 2008

1380-6165

Heavy metal (Cd, Cr, Pb, Hg) concentrations and distributions have been fully studied within Bahía Blanca estuary inner area, which is strongly influenced by urban and industrial stress. Not only metals dissolved in estuarine water but also those included in sediments and suspended particulate matter (SPM) was measured. In all cases internationally standardized protocols were applied to metal measurements, including analytical quality check test through analysis of certified reference materials. Total metal contents from surface sediments and SPM were compared with those from an historical database of the area, as well as with values representing the natural geochemical baseline within the system. Each metal enrichment factor was computed for each site in order to assess both the polluting metals and the degree of pollution at each location. Results revealed that heavy metal pollution is mainly localized in the areas close to the industrial effluents discharge system as well as to the urban sewage outfall discharge. Data from sequential extractions indicate that metals from anthropogenic sources (mainly Cd and Pb) are potentially more mobile than those inherited from geological parent material. The influences of other potential sources of metals (i.e. streams, runoff) were also considered. Heavy metals adsorbed to SPM were particularly examined considering the influence of this process on both bioavailability and toxicity of trace metals in natural waters. Finally, the normalization of measured metal concentrations against background reference elements (i.e. Al or Fe) allowed us to identify the lithogenic or the anthropogenic origin of these pollutants within Bahía Blanca estuary.