Geochemical distribution and bioavailability of heavy metals and oxalate in street sediments from Rio de Janeiro, Brazil: a preliminary investigation.

As urbanisation accelerates within less-economically developed countries, populations in cities such as Rio de Janeiro are subject to numerous health risks relating to "heavy metal", sewage and vehicle pollution. These risks apply especially to children, through inhalation and dermal contact with pollutant-rich street sediments that reflect contamination from atmospheric deposition and act as effective sinks for heavy metals and oxalates. To assess the nature and extent of these risks street sediments were collected from industrial, commercial, residential and recreational areas with varying traffic densities within Rio de Janeiro. A modified selective extraction procedure was used to study the geochemical partitioning and bioavailability of Fe, Mn, Zn, Cu, Cr, Ni, Pb and C(2)O(4) (-). Oxalate partitioning has not been studied by traditional sequential methods and results from this procedure highlight the potential bioavailability of both oxalates and "heavy metals", especially Pb and C(2)O(4) (-) in industrial and recreational areas.