You are here:
Stream mesocosm salt ecotoxicology studies help inform aquatic life criteria
Citation:
Nietch, C., J. Lazorchak, AND N. Smucker. Stream mesocosm salt ecotoxicology studies help inform aquatic life criteria. Society for Freshwater Science Annual Meeting, Salt Lake, Utah, May 19 - 23, 2019.
Impact/Purpose:
Discharges elevated in the content of major ions are a growing threat to aquatic life in freshwater systems. Major ions mostly are Na+, Ca2+, Mg2+, Cl-, SO42-, & HCO3-. Increases in any or all of these ions can significant increase salinity leading to freshwater salinization. Studies were undertaken to examine how different recipes of excess major ions affect single-species toxicity and whole-community stream mesocosm responses. Using dose-response designs, effective concentrations (EC) for single species, community-level, and functional variables were modeled and ranked. Hazard concentrations (HCs) were then compared among different dosing recipes and field data. The performance of different measures for assessing the relative toxicity among recipes was also evaluated. These comparisons and evaluation is relevant to the derivation and application of aquatic life criteria.
Description:
Studies were undertaken to examine how different recipes of excess major ions (Na, Ca, Mg, SO4, HCO3, Cl) affect single-species toxicity and whole-community stream mesocosm responses. Using dose-response designs, effective concentrations (EC) for single species, community-level, and functional variables were modeled and ranked. Hazard concentrations (HCs) were then compared among different dosing recipes and field data. The performance of different measures for assessing the relative toxicity among recipes was also evaluated. For instance, the HCs for specific conductance from EC50-based response sensitivity distributions significantly differed between a recipe simulating oil and gas produced waters (HC5=792 µS/cm (685–933, 95% CI)) and one simulating leachate from surface coal mining (HC5=434 µS/cm (338–584, 95% CI)). Evaluating these different sensitivities within the context of a proposed TDS limit of 500 mg/l for NPDES permits applicable to Central Appalachian dischargers and a field-based conductivity benchmark (ca. 300 µS/cm) for the same region is relevant to the derivation and application of aquatic life criteria. Potentially important ambiguity in the way different measures of excess ionic content characterize relative toxicity also needs consideration.