Application of Bioavailability Models to Derive Chronic Guideline Values for Nickel in Freshwaters of Australia and New Zealand

Abstract

There has been an increased emphasis on incorporating bioavailability-based approaches into freshwater guideline value derivations for metals in the Australian and New Zealand water quality guidelines. Four bioavailability models were compared: the existing European biotic ligand model (European Union BLM) and a softwater BLM, together with 2 newly developed multiple linear regressions (MLRs)-a trophic level-specific MLR and a pooled MLR. Each of the 4 models was used to normalize a nickel ecotoxicity dataset (combined tropical and temperate data) to an index condition of pH 7.5, 6 mg Ca/L, 4 mg Mg/L, (i.e., approximately 30 mg CaCO 3 /L hardness), and 0.5 mg DOC/L. The trophic level-specific MLR outperformed the other 3 models, with 79% of the predicted 10% effect concentration (EC10) values within a factor of 2 of the observed EC10 values. All 4 models gave similar normalized species sensitivity distributions and similar estimates of protective concentrations (PCs). Based on the index condition water chemistry proposed as the basis of the national guideline value, a protective concentration for 95% of species (PC95) of 3 µg Ni/L was derived. This guideline value can be adjusted up and down to account for site-specific water chemistries. Predictions of PC95 values for 20 different typical water chemistries for Australia and New Zealand varied by >40-fold, which confirmed that correction for nickel bioavailability is critical for the derivation of site-specific guideline values.

Comparison of Multiple Linear Regression and Biotic Ligand Models to Predict the Toxicity of Nickel to Aquatic Freshwater Organisms

“…In the European Union, a bioavailability model is used that incorporates DOC, calcium, and pH. Peters et al (2018) used Australian ecotoxicity tests to show that bioavailability principles are supported for water chemistry ranges observed in Australia in natural water experiments; their findings provided the basis for establishing bioavailability‐based water quality guidelines in Australia and New Zealand (Peters et al 2021; Stauber et al 2021). To some extent, differences in guidelines are the result of the organisms (e.g., native species) selected to inform the guidelines.…”

“…In accordance with European guidelines, the Nys et al (2016) approach focuses primarily on the use of chronic data in species‐specific models. Recently, a nickel guideline was developed in Australia by Stauber et al (2021) that was based on trophic level–specific multiple linear regressions (MLRs) developed by Peters et al (2021) with ecotoxicity data from species that would be relevant to Australia and New Zealand. The Stauber et al (2021) analysis also considered the Peters et al (2021) pooled MLR, the Nys et al (2016) bioavailability model, and the Peters et al (2018) bioavailability model.…”

“…Recently, a nickel guideline was developed in Australia by Stauber et al (2021) that was based on trophic level–specific multiple linear regressions (MLRs) developed by Peters et al (2021) with ecotoxicity data from species that would be relevant to Australia and New Zealand. The Stauber et al (2021) analysis also considered the Peters et al (2021) pooled MLR, the Nys et al (2016) bioavailability model, and the Peters et al (2018) bioavailability model. The approach that has been adopted in the United States and Canada combines data from broad taxonomic groups into a single “pooled” model for either acute data, chronic data, or all data (Brix et al 2017; DeForest et al 2017; Environment and Climate Change Canada 2019).…”

Empirical Bioavailability Corrections for Nickel in Freshwaters for Australia and New Zealand Water Quality Guideline Development

“…This is likely to be especially important when species from different trophic levels account for the most sensitive species in the SSD. When the most sensitive species always remain the same even under different water chemistry conditions, then there is a good argument for simplifying the approach to only normalizing the HC5 value, but this may not be the case for the SSD used to derive the guideline value (Stauber et al 2020).…”

“…A database of chronic nickel toxicity data (Stauber et al 2020), including all the water quality parameters that were available for each study, for both tropical and temperate exotic and native freshwater species, was compiled, and quality assessed following the method of Warne et al (2018). Only chronic data scoring >50% and with measured dissolved nickel concentrations were included in the final nickel freshwater ecotoxicity dataset.…”