Development of a bioavailability-based acute effects assessment method for nickel.

Area of Science:

• Environmental Toxicology
• Aquatic Ecotoxicology
• Nickel (Ni) Bioavailability

Background:

• Nickel (Ni) is a common aquatic contaminant.
• Existing environmental thresholds for Ni may not fully account for water chemistry variations.
• Bioavailability-based approaches are crucial for accurate ecotoxicity assessments.

Purpose of the Study:

• To develop a bioavailability-based effects assessment method for deriving acute freshwater environmental thresholds for nickel (Ni) in Europe.
• To revise and propose an average invertebrate bioavailability model for Ni.
• To integrate this model with fish and algae models for a comprehensive Ni normalization approach.

Main Methods:

• Compiled a comprehensive acute freshwater Ni ecotoxicity database (63 species).
• Revised Ni bioavailability models for invertebrates, integrating Ca2+, Mg2+, and pH effects.
• Validated the invertebrate model with 15 species and evaluated extrapolation to plants.
• Combined bioavailability models with toxicity data for a normalized species sensitivity distribution (SSD) approach.

Main Results:

• A novel average invertebrate bioavailability model for Ni was developed and validated.
• The model integrates Ca2+, Mg2+ competition and pH effects on Ni toxicity.
• The proposed bioavailability normalization approach for Ni is applicable to ~70% of European freshwaters.
• Site-specific acute environmental thresholds (HC5L(E)C50) for Ni can be derived.

Conclusions:

• The developed bioavailability-based method enhances the accuracy of acute environmental threshold derivation for Ni.
• This approach provides a robust framework for incorporating bioavailability into Ni risk assessment and compliance monitoring in European freshwaters.
• Further research is needed to address uncertainties in applying Ni bioavailability models to plant species.