Bioconcentration, bioaccumulation, biomagnification and trophic magnification: a modelling perspective.

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Biomolecular Modeling

Background:

• Quantifying bio-uptake of organic chemicals in fish is crucial for ecological risk assessment.
• Existing models for bioaccumulation metrics (e.g., CKk, fZD) have different strengths.
• Understanding chemical uptake kinetics and equilibria is vital for regulatory purposes.

Purpose of the Study:

• To present equivalent modeling approaches for quantifying bio-uptake metrics in fish.
• To evaluate the influence of chemical properties (log Kow) and fish characteristics (lipid content) on bioaccumulation and biomagnification.
• To propose a strategy for advancing bioaccumulation science.

Main Methods:

• Developed and applied one-compartment steady-state models with approximately 13 parameters.
• Simulated bioaccumulation of hypothetical non-biotransforming chemicals (log Kow 4-8) in fish of varying lipid content.
• Simulated a 5-species linear food chain to evaluate trophic magnification factors (TMFs).

Main Results:

• CKk and fZD models are equivalent for quantifying bio-uptake.
• Biomagnification factors are sensitive to fish lipid content.
• Lipid normalization is most insightful for less hydrophobic chemicals (log Kow < 5), while wet-weight concentrations are more insightful for highly hydrophobic chemicals.

Conclusions:

• A simple, parameter-parsimonious model is adequate for understanding bio-uptake equilibria and kinetics.
• Both respiratory and dietary uptake kinetics play critical roles in bioaccumulation, depending on hydrophobicity.
• An integrated approach combining monitoring, laboratory data, and modeling is recommended to validate bioaccumulation science.