Geochemical Distribution and Bioavailability of Heavy Metals and Oxalate in Street Sediments from Rio de Janeiro, Brazil: A Preliminary Investigation

Abstract

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.

Risk assessment of metals in road-deposited sediment along an urban–rural gradient

“…Accordingly, we assigned a comparatively lower level value for the range of larger RDS mass per unit area because coarser particles had lower risk of metal toxicity and mobility. In addition, other factors such as metal chemical fractions could be considered in future studies to provide a better understanding of metals toxicity (McAlister et al, 2005;Kartal et al, 2006). …”

The contribution of heavy metal pollution derived from highway runoff to Guanabara Bay sediments: Rio de Janeiro / Brazil

“…Along with sewage, urban street runoff has been identified as one of the main sources of heavy metals to coastal and estuarine systems (e.g. Odun and Drifmeyer 1978, Ellis 1979, Pope 1980, Lacerda et al 1987, Smith and Orford 1989, Watts and Smith 1994, Chon et al 1995, Baptista Neto et al 1999, McAllister et al 2000, 2005.…”

The Role of the Humic Substances in the Fractioning of Heavy Metals in Rodrigo de Freitas Lagoon, Rio de Janeiro - Brazil

“…The selective extraction protocol (McAlister et al 2005) is shown in Table I. In this study the extraction of the organic phase was modified.…”

“…This technique offers a differential approach, whereby those operationally defined solid phases that bind these metals is examined. It provides a better understanding of metal retention and bioavailability under different environmental conditions, as well as providing additional information to enhance analytical interpretation (Tessier et al 1979, Ure et al 1983, Rauet 1989, McAlister et al 2005, McAlister et al 2008 Samples were weighed into acid washed polypropylene tubes and all extracts were collected in acid washed high-density polyethylene (HDPE) containers prior to analysis. Reference material is not available to allow quality control monitoring of selective extraction.…”