PH08 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Thursday
(PH083) Effects of water quality parameters on chronic nickel toxicity to Ceriodaphnia dubia.
Wirtz, J1, Stubblefield, W1, De Schamphelaere, K2, Naddy, R3, Ortego, L4, Schlekat, C4, 1 Parametrix, Corvallis, OR, USA2 Ghent University, Ghent, Belgium3 ENSR, Fort Collins, CO, USA4 NiPERA, Durham, NC, USA
ABSTRACT- Water quality parameters (e.g., hardness, alkalinity, pH, and natural organic matter [NOM]) have been shown to affect acute nickel (Ni) toxicity to a variety of aquatic species. However, little information is available regarding the effect of these parameters on chronic Ni toxicity. To address this, a systematic series of toxicity tests were conducted to evaluate the potential modifying effects of water quality parameters on chronic Ni toxicity to Ceriodaphnia dubia. Study results identified changes in chronic Ni toxicity attributable to water hardness and alkalinity, as well as increases in chronic C. dubia toxicity with increasing pH. Toxicity tests conducted in natural waters yielded substantial differences from laboratory water-based tests – water effect ratios (WERs) ranging from 3 to 18 indicated a moderating effect of NOM on chronic Ni toxicity. It was not possible to develop a biotic ligand model (BLM) for chronic Ni toxicity with the current dataset, but the construction of a multi-variate model that incorporates the effects of the key water quality parameters on chronic Ni toxicity was possible. Additionally, previous studies have indicated substantial differences in acute and chronic Ni toxicity to cladocera (i.e., high acute to chronic ratios). To investigate one potential explanation for this observation, Ni tissue concentrations were monitored in organisms continuously exposed to Ni for two to eight days. Tissue Ni concentrations generally increased in C. dubia over time, but significant differences in the Ni tissue burdens in the control vs. experimental groups were not evident until the eighth day of exposure.
Key words: chronic toxicity, nickel, water quality parameters, biotic ligand model (BLM)