TOXICITY AND ACCUMULATION OF ZINC AND COPPER IN HYALELLA-AZTECA EXPOSED TO METAL-SPIKED SEDIMENTS

The relationship between zinc and copper toxicity in Hyalella azteca a nd accumulation from metal-spiked sediments was determined for future use in identifying sites where these metals contribute to sediment tox icity. Both zinc and copper accumulation increased rapidly with increa sing sediment concentrations, showing no evidence of saturation as see n in waterborne exposures. Zinc accumulation from zinc spiked sediment s was substantial, even at concentrations below those causing chronic toxicity, and body concentrations can readily be used to infer chronic toxicity. Chronic toxicity in spiked sediment exposures occurred at e xcess (above background) body concentrations twice as high as in water borne exposures, possibly as a result of zinc in gut contents. In cont rast, chronic copper toxicity occurred at body concentrations lower th an those observed in waterborne exposures. Furthermore, body copper at low sediment exposures was independent of copper in sediment. Body co pper concentrations can be used to infer short-term (1-week) toxicity but not chronic toxicity. Copper, but not zinc, caused a reduction in growth, even at concentrations below the 4-week LC25. Reduced growth c an, therefore, be used to differentiate between chronic copper and zin c toxicity in sediments.