Robust Guidelines and Assessment Procedures for Metal-Contaminated Sediments

Background	The project aims to develop a more defensible way of assessing the impact of metal-contaminated sediments. Globally, sediment quality guidelines (SQGs) for metals vary over several orders of magnitude and and are not based on clear cause-effect relationships. Although equilibrium partitioning approaches to developing SQGs have been attempted, the cause-effect relationships are weak due to the many other factors that influence metal bioavailability and toxicity. The lack of defensible SQGs for metals currently impedes decision making processes by both regulators and industries.
Objectives	Reassess the sensitivity of benthic organisms to common metal contaminants and the appropriateness of current interim SQGs for metals; Assess the importance of 'contaminant exposure pathways' in regards to data used for species sensitivity distribution approaches for developing SQGs for metal toxicants; Develop a new effects-based SQG for copper in estuarine/marine sediments; Develop and test toxicity identification evaluation (TIE) methodologies for whole sediments; and Develop and apply weight-of-evidence (WoE) based TIE procedures using lines-of-evidence (LoE) from (i) varied species sensitivity to contaminants, (ii) varied contaminant exposure pathways (water, sediment food), and (iii) results from whole-sediment TIE and pore water TIE manipulations (using species with differing sensitivity and exposure pathways).
Methodology	The project consists of two sub-projects, involving (i) the development of cause-effect based SQGs for sediment metals, and (ii) the development of improved TIE procedures to identify causality in metal-contaminated sediments. The first sub-project is being achieved through improved understanding of the sensitivity of organisms to metals in waters (pore waters and overlying waters) and sediments (different particulate phases and food sources). The second sub-project involves development of in-house whole sediment TIE techniques and testing of these techniques and those developed by other scientists on a range of metal contaminated sediments.
More Information	graeme.batley@csiro.au

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