John Wiley & Sons, Ltd.

Preparation and characterization of nickel‐spiked freshwater sediments for toxicity tests: Toward more environmentally realistic nickel partitioning

0
We compared two spiking methods and evaluated nickel (Ni) partitioning during a series of toxicity tests with eight different freshwater sediments having a range of physico‐chemical characteristics. A two‐step spiking approach with immediate pH adjustment by addition of NaOH at a 2:1 molar ratio to the spiked Ni was effective in producing consistent pH and other chemical characteristics across a range of Ni spiking levels. When Ni was spiked into sediment having a high acid‐volatile sulfide (AVS) and organic matter content, a total equilibration period of at least 10 weeks was needed to stabilize Ni partitioning. However, highest spiking levels evidently exceeded sediment binding capacities; therefore, a 7‐d equilibration in toxicity test chambers and 8 volume‐additions/day of aerobic overlying water was used to avoid unrealistic Ni partitioning during toxicity testing. The 7‐d pre‐test equilibration allowed “excess” spiked Ni and other ions from pH adjustment to diffuse from sediment pore water and promoted development of an environmentally relevant, 0.5 to 1‐cm oxic/sub‐oxic sediment layer in the test chambers. Among the eight different spiked sediments, the logarithm of sediment/pore water distribution coefficient values (log Kd) for Ni during the toxicity tests ranged from 3.5 to 4.5. These Kd values closely match the range of values reported for various field Ni‐contaminated sediments, indicating that testing conditions with our spiked sediments were environmentally realistic. Environ Toxicol Chem © 2013 SETAC

Customer comments

No comments were found for Preparation and characterization of nickel‐spiked freshwater sediments for toxicity tests: Toward more environmentally realistic nickel partitioning. Be the first to comment!