Biomarkers as tools to assess sediment quality: Laboratory and field surveys

Abstract

The traditional approach to assessing sediment quality involves chemical analysis. However, this is not sufficient to ensure safe disposal of dredged material or to determine the impact on biota of sediment contamination. The toxic effect on flora and fauna is related to the bioavailability of contaminants. Because of the potential transfer of contaminants along food chains, not only the local habitat can be affected, but also organisms at higher trophic levels. The consumption of seafood may lead to adverse effects on human health. Biomarkers are useful tools as early warnings to determine exposure to contaminants and the effect of contaminants on organisms before the damage becomes irreversible. They may link the bioavailability of compounds with their concentrations at target organs and intrinsic toxicity. Nevertheless, other confounding factors must be taken into account when the results are interpreted. We review different biomarkers used to determine the quality of marine sediment and dredged material. Also, we consider evaluation of the use of biomarkers in environmental risk assessment (ERA) and links between laboratory and field surveys. We integrate available information to determine the validity of the different biomarkers, their relevance for assessing contaminated sediments and the suitability of the methodology. We consider the results in a tiered approach to testing at levels characterizing toxic effects and validating in situ changes.