Nickel toxicity to benthic organisms: The role of dissolved organic carbon, suspended solids, and route of exposure

- Aquatic invertebrate Ni toxicity was tested compartmentally: waterborne, sediment, and food.
- Compartment design included DOC and TSS exposures with two sediment types.
- Invertebrates experienced either lethal or sublethal Ni effects in all compartments.
- Ni bioavailability increased with sediment type, and bioaccumulated from water and dietary sources.
- Organism toxicity showed Ni-water > Ni-sediment > Ni-all (water, sediment, food) > Ni-food.

Nickel bioavailability is reduced in the presence of dissolved organic carbon (DOC), suspended solids (TSS), and other complexing ligands; however, no studies have examined the relative importance of Ni exposure through different compartments (water, sediment, food). Hyalella azteca and Lymnaea stagnalis were exposed to Ni-amended water, sediment, and food, either separately or in combination. Both organisms experienced survival and growth effects in several Ni compartment tests. The DOC amendments attenuated L. stagnalis Ni effects (survival, growth, and 62Ni bioaccumulation), and presence of TSS exposures demonstrated both protective and synergistic effects on H. azteca and L. stagnalis. 62Ni trophic transfer from food to H. azteca and L. stagnalis was negligible; however, bioaccumulating 62Ni was attributed to 62Ni-water (62Ni flux from food), 62Ni-TSS, and 62Ni-food. Overall, H. azteca and L. stagnalis Ni compartment toxicity increased in the following order: Ni-water >> Ni-sediment >> Ni-all (water, sediment, food) >> Ni-food.