PT13 Aquatic Ecotoxicology I
Exhibit Hall
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(PT178) Copper bioavailability in South Carolina Waters with low hardness: organism response and analytical measures.

Bearr, J1, Garber, K2, Rodgers Jr., J2, 1 Tetra Tech, Inc., Owings Mills, MD2 Clemson University, Clemson, SC

ABSTRACT- Only a portion of the total copper concentration introduced to aquatic systems is bioavailable. With this concept in mind, Water Quality Criteria for copper were devised as a means to protect aquatic life from excessive metal exposure, both concentration and form. A sensitive approach, which can discern subtle changes in bioavailability, could provide greater assurance for protection of organisms based on site-specific copper bioavailability. For this research, copper bioavailability was measured as a change in the response of test organisms with a change in exposure. Aqueous copper concentrations were measured using acid-soluble, soluble, and anodic stripping voltammetry (ASV) techniques to determine which is most applicable for prediction of copper toxicity for the different organisms used in toxicity experimentation. Water was sampled from specific sites with low hardness (<50 mg/L as CaCO3) in the Savannah, Saluda, and Catawba watersheds in the Piedmont region of South Carolina. Copper toxicity experiments were conducted with Ceriodaphnia dubia, Pimephales promelas, and Typha latifolia. Results indicated copper was more potent to C. dubia in comparison with the other test organisms used in these experiments. For C. dubia, copper potency ranged from 6.8 to 24 g Cu/L for the waters tested. This test organism was useful for discerning subtle differences in copper bioavailability in comparison to the other species tested in these waters. For three of the four waters, exposure-response relationships for C. dubia were not significantly different when soluble or ASV techniques were used to measure bioavailable copper. Acid soluble measurements of copper resulted in different exposure-response relationships for C. dubia. Of the organisms tested under these conditions, C. dubia offered a greater ability to discern subtle changes in copper bioavailability.

Key words: hardness, bioavailability, copper, organism response

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