Abstract: Under the condition of sediment exposure, the kinetic parameters of the absorption process of accumulation and elimination of heavy metals Cu and Pb in Meretrix meretrixwere investigated using a semi-static two-compartment kinetic model. The kinetic parameters of bioconcentration were obtained from the model by nonlinear curve fitting, including uptake rate constant (K₁), elimination rate constant (K₂), bioconcentration factor (BCF), and biological half-life (B_1/2).The modeling results showed that K₁ ranged from 4.6333 to 72.3754, K₂ ranged from 0.0512 to 0.0798, BCF ranged from 60.7646 to 1414.9634, and B_1/2 ranged from 8.69 to 13.55. We found that the metal concentration data was confirmed to the two-compartment model, and that good agreement was found between the predicted and observed metal concentrations using the goodness-of-fit test under the condition of sediment exposure. The results also indicated that K₁ and BCF of M. meretrixgenerally decreased with the increase of heavy metal exposure concentration in the ambient seawater, that the bioaccumulation ability order to the two heavy metals was Cu>Pb, that B_1/2 of Cu was longer than that of Pb, and that maximal content in the organism (C_Amax) at the theoretic equilibrium increased and was basically proportiona1to increasing metal concentration in the water. The experimental results showed that the semi-static two-compartment kinetic model could well fit the bioconcentration of heavy metals Cu and Pb in M. meretrix, but requires further experimental research and analysis under different conditions.

Key words: Meretrix meretrix, heavy metal, bioaccumulation, kinetics, sediment exposure