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Characterizing toxicity of metal-contaminated sediments from mining areas

•We review methods for testing toxicity of sediments affected by metals.•Toxicity testing provides site-specific assessment of impacts on resident biota.•Goals are to document extent of toxicity and associations with metal exposure.•Need to characterize bioavailability of metals in sediment and pore...

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Bibliographic Details
Published in:Applied geochemistry 2015-06, Vol.57, p.73-84
Main Authors: Besser, John M., Brumbaugh, William G., Ingersoll, Christopher G.
Format: Article
Language:English
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Summary:•We review methods for testing toxicity of sediments affected by metals.•Toxicity testing provides site-specific assessment of impacts on resident biota.•Goals are to document extent of toxicity and associations with metal exposure.•Need to characterize bioavailability of metals in sediment and pore water.•Toxicity data is basis for guidelines used to predict hazards of metal toxicity. This paper reviews methods for testing the toxicity of metals associated with freshwater sediments, linking toxic effects with metal exposure and bioavailability, and developing sediment quality guidelines. The most broadly applicable approach for characterizing metal toxicity is whole-sediment toxicity testing, which attempts to simulate natural exposure conditions in the laboratory. Standard methods for whole-sediment testing can be adapted to test a wide variety of taxa. Chronic sediment tests that characterize effects on multiple endpoints (e.g., survival, growth, and reproduction) can be highly sensitive indicators of adverse effects on resident invertebrate taxa. Methods for testing of aqueous phases (pore water, overlying water, or elutriates) are used less frequently. Analysis of sediment toxicity data focuses on statistical comparisons between responses in sediments from the study area and responses in one or more uncontaminated reference sediments. For large or complex study areas, a greater number of reference sediments is recommended to reliably define the normal range of responses in uncontaminated sediments – the ‘reference envelope’. Data on metal concentrations and effects on test organisms across a gradient of contamination may allow development of concentration-response models, which estimate metal concentrations associated with specified levels of toxic effects (e.g. 20% effect concentration or EC20). Comparisons of toxic effects in laboratory tests with measures of impacts on resident benthic invertebrate communities can help document causal relationships between metal contamination and biological effects. Total or total-recoverable metal concentrations in sediments are the most common measure of metal contamination in sediments, but metal concentrations in labile sediment fractions (e.g., determined as part of selective sediment extraction protocols) may better represent metal bioavailability. Metals released by the weak-acid extraction of acid-volatile sulfide (AVS), termed simultaneously-extracted metals (SEM), are widely used to estimate the ‘potentia
ISSN:0883-2927
1872-9134
DOI:10.1016/j.apgeochem.2014.05.021