Guidelines for copper in sediments with varying properties

A major weakness of sediment quality guidelines (SQGs) is their poor ability to predict how toxicity thresholds change for different sediment types. Using species sensitivity distributions (SSDs) of copper effects data, new guidelines were derived for copper in non-sulfidic marine sediments in which organic carbon (OC) and particle size strongly influence copper bioavailability. The derived SQGs varied in a predictable manner with changes in sediment particle size and organic carbon (OC), and were shown to offer a significant improvement on the existing ‘single value’ SQG. Adequate protection for all benthic organisms is expected to be achieved for a OC-normalised copper concentration of 3.5 mg Cu g−1 OC in the <63 μm sediment fraction. For short-term exposures, the equivalent acute guideline is 11 mg < 63 μm Cu g−1 OC. The new SQGs incorporate a high degree of conservatism owing to the use of copper-spiked sediments and laboratory-based bioassays that were expected to result in greater metal exposure of organisms to bioavailable copper than would be expected for field-contaminated sediments with similar total copper concentrations. SQGs that vary with sediment properties were prepared in an easily referenced tabular format.

► The study addresses the need for sediment quality guidelines (SQGs) that change for different sediment types. ► The effects of copper on benthic organisms is reviewed. ► New copper effects data created for benthic invertebrates. ► Species sensitivity distributions (SSDs) of copper effects data are used to derive new guidelines for copper in sediments. ► Copper SQGs are proposed that vary with sediment properties and presented in an easily referenced tabular format.