Temperature-dependent bioaccumulation of polycyclic aromatic hydrocarbons

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Chemical Risk Assessment

Background:

• Bioaccumulation factors (BAFs) are crucial for assessing chemical risks in sediments and soils.
• Determining BAFs for hydrophobic organic chemicals (HOCs) is challenging, often relying on modeling due to data scarcity and the unknown applicability of lab-derived values to field conditions.
• Field exposure conditions (temperature, pH, salinity) vary, unlike standardized laboratory settings.

Purpose of the Study:

• To investigate the impact of temperature on the bioaccumulation of hydrophobic organic chemicals (HOCs), specifically polycyclic aromatic hydrocarbons (PAHs), in aquatic organisms.
• To develop a predictive model for PAH bioaccumulation based on temperature and chemical hydrophobicity.
• To evaluate polydimethylsiloxane (PDMS) as a surrogate for animal lipids in bioaccumulation studies.

Main Methods:

• Utilized polydimethylsiloxane (PDMS)-coated solid-phase microextraction (SPME) fibers to study the bioaccumulation of PAHs in aquatic worms.
• Investigated the effect of varying temperatures on PAH bioaccumulation.
• Derived a two-parameter linear free energy relationship to predict PAH bioaccumulation.

Main Results:

• Bioaccumulation of non-metabolizable HOCs was found to be an exothermic, enthalpy-driven process, decreasing as temperature increases.
• Aquatic organisms may accumulate several times more HOCs in winter compared to summer, with potential ecotoxicological consequences.
• Polydimethylsiloxane (PDMS) partitioning thermodynamics indicate it is not a suitable surrogate for animal lipids in bioaccumulation studies.

Conclusions:

• Temperature significantly influences the bioaccumulation of HOCs, with lower temperatures leading to higher accumulation.
• A predictive model relating temperature and hydrophobicity to PAH bioaccumulation was successfully derived.
• Solid-phase microextraction (SPME) is an effective analytical tool for measuring aqueous concentrations, enabling subsequent bioaccumulation estimation using BAFs.