John Wiley & Sons, Ltd.

Toxicological effects of short‐term resuspension of metal‐contaminated freshwater and marine sediments

Sediments in navigation‐dominated waterways are frequently contaminated with a variety of particle‐associated pollutants and are subject to frequent short‐term resuspension events. There is little information documenting whether resuspension of metal‐contaminated sediments has adverse ecological effects on resident aquatic organisms. Using a novel laboratory approach, we examined the mobilization of Zn, Cu, Cd, Pb, Ni and Cr during resuspension of a freshwater and two coastal marine sediments and whether resuspension and redeposition resulted in toxicity to model organisms. Sediment flux exposure chambers (SeFEC) were used to resuspend metal‐contaminated sediments from one site in Lake DePue, Illinois, and two sites in Portsmouth Naval Shipyard, Maine. Short‐term (4 h) resuspension of sediment at environmentally relevant suspended particulate matter concentrations (< 1 g/L) resulted in metal mobilization to water that was sediment and metal specific. Overall, the net release of metals from suspended particles was limited, likely due to scavenging by organic matter and Fe oxides that formed during sediment interaction with oxic water. Minimal toxicity to organisms (survival of Hyalella azteca and Daphnia magna; survival, growth, and tissue metal concentration of Neanthes arenaceodentata; bioluminescence of Pyrocystis lunula) was observed during 4‐h exposure to resuspended sediments and during 4‐ to 10‐d post‐exposure recovery periods in uncontaminated water. Redeposited suspended particles exhibited increased metal bioavailability and toxicity to H. azteca, highlighting the potential for adverse ecological impacts due to changes in metal speciation. It is important to consider interactions between organisms' life histories and sediment disturbance regimes when assessing risks to ecosystems. This article is protected by copyright. All rights reserved

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