Metal Oxides in Surface Sediment Control Nickel Bioavailability to Benthic Macroinvertebrates

Abstract

In aquatic ecosystems, the cycling and toxicity of nickel (Ni) are coupled to other elemental cycles that can limit its bioavailability. Current sediment risk assessment approaches consider acid-volatile sulfide (AVS) as the major binding phase for Ni, but have not yet incorporated ligands that are present in oxic sediments. Our study aimed to assess how metal oxides play a role in Ni bioavailability in surficial sediments exposed to effluent from two mine sites. We coupled spatially explicit sediment geochemistry (i.e., separate oxic and suboxic) to the indigenous macroinvertebrate community structure. Effluent-exposed sites contained high concentrations of sediment Ni and AVS, though roughly 80% less AVS was observed in surface sediments. Iron (Fe) oxide mineral concentrations were elevated in surface sediments and bound a substantial proportion of Ni. Redundancy analysis of the invertebrate community showed surface sediment geochemistry significantly explained shifts in community abundances. Relative abundance of the dominant mayfly (Ephemeridae) was reduced in sites with greater bioavailable Ni, but accounting for Fe oxide-bound Ni greatly decreased variation in effect thresholds between the two mine sites. Our results provide field-based evidence that solid-phase ligands in oxic sediment, most notably Fe oxides, may have a critical role in controlling nickel bioavailability.

Hitting Reset on Sediment Toxicity: Sediment Homogenization Alters the Toxicity of Metal‐Amended Sediments

“…Accounting for bioavailability with SEM/AVS approaches (US Environmental Protection Agency 2005) reduced variability in concentration-response thresholds for Cu only. Differences in concentration-response values between Raisin and Burntwood sediments amended with Ni were not minimized by accounting for AVS and organic carbon or bulk partitioning to porewater in anoxic sediment, and this supports the observation from other studies that Fe oxides in surface sediment are a more important ligand for Ni binding (Costello et al 2011Besser et al 2013;Mendonca et al 2017). Regardless of sediment type, preparation technique, or metal, no laboratory-prepared sediment with AVS in excess of SEM caused toxicity, which has been demonstrated repeatedly in laboratory and field studies (Di Toro et al 1992;Burton et al 2005;US Environmental Protection Agency 2005;Costello et al 2011).…”

“…Nevertheless, without an understanding of the role of sediment wileyonlinelibrary.com/ETC © 2019 SETAC Homogenization resets toxicity of metal-amended sediment-Environmental Toxicology and Chemistry, 2019;38:1995 oxidation and the stability of metal-binding ligands under oxidizing conditions (which influence metal partitioning and toxicity), traditional sediment toxicity methods are not well suited to predict in situ toxicity. The present study adds to the growing body of literature demonstrating the importance of oxidized ligands, sediment disturbance, and nonequilibrium dynamics in surface sediments (Simpson et al 1998(Simpson et al , 2012Atkinson et al 2007;Costello et al 2011Costello et al , 2015Fetters et al 2016;Mendonca et al 2017), and emphasizes the need for well-designed experiments to improve the accuracy of ecological risk assessment.…”

“…This suggests that even state-ofthe-art laboratory sediment toxicity tests are still falling short of simulating natural conditions. Field and mesocosm experiments have highlighted the limitations of laboratory assays for translating impairment thresholds for metals into effects thresholds observed under field conditions (Burton et al 2005;Costello et al 2011Costello et al , 2015Costello et al , 2016Mendonca et al 2017). In general, laboratory-derived thresholds for metals are overly conservative compared with concentrations at which effects are observed in either mesocosm or field studies (Costello et al 2011(Costello et al , 2015.…”

Weight‐of‐Evidence Approach for Assessing Removal of Metals from the Water Column for Chronic Environmental Hazard Classification

“…Such studies are of limited use because it is well established that exposure to "total" metals does not correlate with adverse effects or toxicity. Studies using caged Hyalella azteca and indigenous benthic macroinvertebrate colonization of metal-spiked sediments showed that benthic macroinvertebrates were unaffected as metals quickly partitioned out, unless concentrations exceeded AVS and Fe oxide binding thresholds (Burton et al 2005;Nguyen et al 2011;Costello et al 2011Costello et al , 2012Costello and Burton 2014;Custer et al 2016aCuster et al , 2016bMendonca et al 2017).…”

Concise Review of Nickel Human Health Toxicology and Ecotoxicology

“…Costello et al [220] demonstrated that this decrease in toxicity can be explained by a transition in partitioning and mineralogy from more labile sediment phases like sulfides to more stable phases like iron oxides. Mendonca et al [221] demonstrated that nickel bioavailability is controlled by iron oxides in a field contaminated site. Together, this information suggests that the bioavailability-based HC5 using laboratory ecotoxicity data is highly protective of effects that are observed in the field.…”