Demonstrating the Reliability of bio‐met for Determining Compliance with Environmental Quality Standards for Metals in Europe

Abstract

The importance of considering the bioavailability of metals in understanding and assessing their toxicity in freshwaters has been recognized for many years. Currently, biotic ligand models (BLMs) are being applied for the derivation and implementation of environmental quality standards (EQS) for metals under the Water Framework Directive in Europe. bio-met is a simplified tool that was developed for implementing bioavailability-based EQS for metals in European freshwaters. We demonstrate the reliability of the relationship between the full BLM predictions and the thresholds (hazardous concentration affecting 5% of species [HC5] values) predicted by bio-met in 3 stages, for the metals copper, nickel, and zinc. First, ecotoxicity data for specific species from laboratory tests in natural waters are compared with predictions by the individual species BLMs included in the full BLMs. Second, the site-specific HC5 values predicted by bio-met for the natural waters used for ecotoxicity testing are compared with those provided by the full BLMs. The reliability of both relationships is demonstrated for all 3 metals, with more than 80% of individual species BLM predictions being within a factor of 3 of the experimental results, and 99% of bio-met local HC5 predictions being within a factor of 2 of the full BLM result. Third, using a larger set of European natural waters in addition demonstrates the reliability of bio-met over a broad range of water chemistry conditions. bio-met is therefore an appropriate tool for performing compliance assessments against EQS values in Europe, due to the demonstrated consistency with the toxicity test data.

Assessing the Extent of Environmental Risks From Nickel in European Freshwaters: A Critical Reflection of the European Commission's Current Approach

“…Simple, user‐friendly tools are available for performing assessments of Ni bioavailability such as bio‐met. Bio‐met has been demonstrated to provide reliable predictions (Peters et al, 2020) of the local bioavailable Ni concentration and the local HC5 value based on the dissolved Ni concentration from data for the local water chemistry conditions (pH, DOC, and Ca). If bioavailability is not considered, it is possible to identify some of the sites at which there is very low potential risk due to Ni, but it is not possible to reliably estimate RQs for sites at which dissolved Ni exposures are elevated.…”

“…To assess samples (and sites) while appropriately accounting for Ni bioavailability, bio‐met v5 (bio‐met 2019) was used as it has been demonstrated to provide reliable results that are fully consistent with the Ni EQS (Peters et al, 2020). Any samples with at least one bioavailability parameter (pH, DOC, Ca) missing (Table 1) could not be assessed for bioavailable Ni concentrations and therefore had to be excluded from the assessment to ensure that the EQS is applied in accordance with the way in which it was set (EC, 2010).…”

Applying Generic Water Quality Criteria to Cu and Zn in a Dynamic Aquatic Environment—The Case of the Brackish Water Formation Strömmen-Saltsjön

“…Plausible explanations to variations in PNEC values in different countries are connected to different water chemistry and hence different bioavailability, as well as different ambient background levels. The Bio-Met tool was recently used to assess differences in bioavailability of Cu in a few European countries (Austria, Belgium, Denmark, France, Germany (River Rhine), Sweden, the Netherlands and the United Kingdom) [30]. The study concluded that freshwaters in Sweden were not among the most sensitive waters in Europe due to high levels of DOC and hence low bioavailability of Cu.…”

“…The inclusion of site-specific biological analyses to complement chemical-based assays can preferably be used for improved precision in environmental risk assessment. The reliability of the Bio-Met tool is well proven and established [30]. Validation was performed at pH levels between 6.0 and 8.5 for both Cu and Zn, and for Ca 2+ concentrations between 3.1 and 129.0 mg/L for Cu and between 5.0 and 160.0 mg/L for Zn.…”

Assessing Nickel Risks in Freshwater to Deliver Better Environmental Protection

“…The inset in Figure 1 shows the cumulative frequency distribution of risk characterization ratios for 3537 sites from 18 European countries for which sufficient data were available from between 2018 and 2020 to perform an assessment of Ni bioavailability. This assessment was performed using bio-met, which is reliable and consistent with the EQS (Peters et al, 2020).…”