Why is metal bioaccumulation so variable? Biodynamics as a unifying concept

Area of Science:

• Environmental toxicology
• Ecotoxicology
• Biogeochemistry

Background:

• Ecological risks of metal contaminants are complex due to species-specific responses, varied metal threats, and intricate environmental factors.
• Existing frameworks struggle to unify these complexities, hindering accurate risk assessment.
• A biologically based conceptualization is needed to integrate these factors for better understanding metal bioaccumulation.

Purpose of the Study:

• To introduce and validate the biodynamic model as a unifying framework for metal bioaccumulation (internal exposure).
• To mechanistically model metal bioaccumulation by integrating geochemical and biological factors.
• To assess the model's predictive accuracy against field observations.

Main Methods:

• Developed a biodynamic metal bioaccumulation model incorporating geochemical site analyses and species-specific physiological constants (influx, loss rates, growth).
• Compiled data from 15 publications forecasting species-specific bioaccumulation.
• Compared model forecasts with field bioaccumulation data across 7 orders of magnitude, 7 metals, 14 species, and 11 environments.

Main Results:

• The biodynamic model forecasts showed strong agreement with field observations, with a coefficient of determination (R2) of 0.98.
• Most forecasts were within a 2-fold agreement with independently observed bioaccumulation data.
• The model successfully predicted metal bioaccumulation across diverse species and environmental conditions.

Conclusions:

• The biodynamic model provides a tenable and unified explanation for metal bioaccumulation.
• This framework advances the realistic understanding of metal toxicity and ecological effects in natural ecosystems.
• The model's success validates its mechanistic and empirical integration of key factors.