Bioavailability of sediment-associated Cu and Zn to Daphnia magna

P. L. Gillis, C. M. Wood, J. F. Ranville, P. Chow-Fraser

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Exposures to mining-impacted, field-collected sediment (Clear Creek, CO, USA) contaminated with Cu (2.4 mg/g) and Zn (5.2 mg/g) were acutely toxic to juvenile Daphnia magna. Dissolved Cu and Zn in the overlying water (sediment + reference water) were at levels that could cause acute toxicity. To reduce dissolved metals below toxic levels, the sediment was repeatedly rinsed to remove any easily mobilized metals. Washing the sediment reduced dissolved Cu by 60% and Zn by 80%. D. magna exposed to washed sediment experienced higher survival (95%) compared to those exposed to the original sediment (<50%). Cu and Zn that remained associated with suspended sediment after washing were not bioavailable, since survival and tissue metal concentrations in D. magna exposed to both filtered (>0.45 μm) and unfiltered overlying water were statistically similar. Multiple regression analysis indicated that only dissolved Cu significantly contributed to mortality of D. magna whereas particulate Cu, particulate Zn, and dissolved Zn did not. Regression analysis on a combined dataset from all Clear Creek exposures (washed and unwashed), revealed a significant (p < 0.0001, r2 = 0.76) relationship between the concentration of dissolved copper in the overlying water and the mortality of exposed Daphnia, yielding an estimated LC50 of 26 μg/L dissolved copper (hardness approximately 140 mg/L). The results of this study indicate that if the sediment of Clear Creek was subjected to a resuspension event that there would be a significant efflux of metals from the sediment into the water column, resulting in potentially toxic levels in the water column.

Original languageEnglish (US)
Pages (from-to)402-411
Number of pages10
JournalAquatic Toxicology
Volume77
Issue number4
DOIs
StatePublished - May 25 2006

Keywords

  • Copper
  • D. magna
  • Labile metals
  • Metal bioavailability
  • Sediment associated metals
  • Zinc

ASJC Scopus subject areas

  • Aquatic Science

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