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PM05 Aquatic Vertebrate/Invertebrate Toxicology
(PM077) Effects of Suspended Solids and Embedded Sediments on Copper Toxicity in Waters with Low Hardness and Alkalinity.
Bearr, J1, Gallagher, J1, Stagg, C1, Rodgers, J1, 1 Department of Forestry and Natural Resources, Clemson, SC
ABSTRACT- To achieve accurate predictions of in situ metal toxicity for aquatic systems, adjustments or modifications of Water Quality Criteria (WQC) are required when specific site water deviates from "standard waters" used in derivation of the generic or national Water Quality Criteria. Suspended or embedded sediment characteristics are not typically considered when site specific modifications are calculated. The objective of this study was to measure the effects of suspended solids and embedded sediment on aqueous copper bioavailability to Ceriodaphnia dubia for South Carolina waters with low hardness and alkalinity. Four waters and sediments were sampled from: 1) Saluda River near Williamston, SC; 2) an unnamed tributary of Upper Three Runs Creek at the Savannah River Site (New Ellenton, SC); 3) Lake Keowee at Seneca, SC; and 4) Lake Wiley near Rock Hill, SC. These waters were amended with copper sulfate to determine 48-h LC50s and Water Effect Ratios (WERs) for C. dubia. In addition, toxicity experiments were conducted with the inclusion of site sediment. Bioavailability under these conditions was primarily driven by the site sediment's capacity for copper partitioning. The source of overlying water did not significantly affect copper toxicity. However, in absence of sediment, aqueous experiments demonstrated significant differences in WERs: 1.9 for Saluda, 3.3 for the unnamed tributary of Upper Three Runs Creek, 0.55 for Lake Keowee, and 5.2 for Lake Wylie. Current procedures based on the Biotic Ligand Model and hardness-based estimates ignore the role of suspended solids and embedded sediments in copper bioavailability and developing site-specific WQC.
Key words: Bioavailability, Copper, Sediment, Suspended Solids
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