M7 PM Metals in the Environment: Aquatic Biological Perspectives
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 327-329

(MEB-1117-844014) Cadmium risks to freshwater life: predicted low-effect values in ambient waters based upon laboratory and field studies.

Mebane, C¹, ¹ U.S. Geological Survey

ABSTRACT- In 2001, the U.S. Environmental Protection Agency (EPA) released updated aquatic life criteria for cadmium (Cd). Since then additional data on the effects of Cd to aquatic life have become available from studies supported by the EPA, Idaho Department of Environmental Quality (IDEQ), and the U.S. Geological Survey (USGS), among others. Updated data on the effects of Cd to aquatic life were compiled, reviewed, and low-effect values were estimated. Low-effect values ("criteria") were calculated using EPA's guidelines for deriving numerical national water quality criteria for the protection of aquatic organisms. Suitable data on the acute effects of Cd to North American freshwater species were located for 60 species representing 53 genera and 31 families; chronic data were located for 28 species in 21 genera and 17 families. The four most sensitive genera to acute exposures were, in order of increasing Cd resistance, Oncorhynchus (Pacific trout and salmon), Salvelinus (charr trout), Salmo (Atlantic trout and salmon), and Cottus (sculpin). The four most sensitive genera to chronic exposures were Hyalella (amphipod), Gammarus (amphipod), Salvelinus, and Cottus. Using the updated data sets, hardness dependent criteria equations were calculated for acute and chronic exposures to Cd. At a hardness of 50 mg/L as calcium carbonate, the resulting acute and chronic criteria values for filtered samples were 0.75 g/L and 0.38 g/L Cd respectively. Using data that were independent of those used to derive the criteria, the criteria conditions were evaluated to estimate whether adverse effects to the biological integrity of natural waters or to species listed as threatened or endangered in Idaho were expected. The vast majority of data indicated that criteria conditions were unlikely to contribute to any overt, adverse effects to either biological integrity or listed species. Some data suggest subtle, adverse effects such as behavioral changes or swimming performance of fish were possible following long-term exposures to low levels of Cd. Careful biological monitoring of invertebrate and fish assemblages would be prudent in the vicinity of discharges containing Cd concentrations which could result in receiving waters approaching criteria.

Key words: cadmium, aquatic life criteria, species-sensitivity distributions