A consensus-based approach for the development of Site-specific Sediment Quality Values in an SW Atlantic region (São Paulo State, Brazil)

Abstract

Sediment quality guidelines (SQGs) or sediment quality values (SQVs) are important tools for identifying areas of interest and chemicals of environmental concern in contaminated sites, assisting in the monitoring and management processes. The Brazilian coastline has a continental-scale, but the country has adopted international guidelines, which do not correspond to the country's specificities, thus requiring the development of regional thresholds. In this study, site-specific SQVs were developed for the coast of São Paulo, the most occupied and industrialized State of Brazil, by using a consensus-based approach. Data on sediment chemistry and toxicity were compiled from 20 studies covering a 20-year period. A Biological Effects Database for Sediments (BEDS) was constructed and threshold levels were produced for toxic effects on the burrowing amphipod Tiburonella viscana in whole sediment exposures. Another set of thresholds was derived by a multivariate approach obtained from a subset of samples of BEDS. Then, geochemical tools were used to calibrate values and a definitive set of SQVs was proposed for trace elements, and total polycyclic aromatic hydrocarbons. Therefore, toxicity is expected to occur at 8.1 and 0.2 µg g–1 for As and Hg respectively, and from 0.4 to 0.8 µg g–1 for Cd, 24.9 to 17.6 µg g–1 for Cr, 10.8 to 14.6 µg g–1 for Ni, 6.7 to 16.6 µg g–1 for Pb, 52.6 to 190.2 µg g–1 for Zn, and 182.6 to 1138.6 ng g–1 for the sum of PAHs. The predictive performance of SQVs was more effective than the international guidelines, including those applied in Brazil for dredged material. Therefore, the site-specific SQVs produced in this study can be employed as a benchmark of environmental quality standards for monitoring purposes of coastal and marine environments in Brazil.