沉积物暴露条件下文蛤Meretrix meretrix 对重金属Cu、Pb的富集动力学研究

应用半静态双箱动力学模型室内模拟了沉积物暴露条件下文蛤Meretrix meretrix 对Cu、Pb的生物富集，通过对富集与排出过程中文蛤体内重金属污染物的动态监测和对富集与排出过程监测结果的非线性拟合，得到了文蛤富集重金属的吸收速率常数K₁、排出速率常数K₂、生物富集因子BCF(bioconcentration factors)、生物学半衰期B_1/2等动力学参数。拟合结果得到的Cu、Pb各动力学参数分别为，K₁为4.6333?72.3754；K₂为0.0512?0.0798；BCF为60.7646?1414.9634；B_1/2为8.69?13.55。对模型的拟合优度检验结果显示，沉积物暴露条件下文蛤对重金属Cu、Pb的生物富集数据符合双箱模型，模型的拟合优度良好。比较结果得出，吸收速率常数K₁及生物富集因子BCF均随着外部水体金属暴露浓度的增大而减小；文蛤对Cu富集能力大于Pb；Cu在文蛤体内的生物学半衰期B_1/2大于Pb；理论平衡状态下生物体内Cu、Pb的含量C_Amax随着外部水体中金属暴露浓度的增大而增大，且呈显著正相关，实验结果表明沉积物暴露条件下双箱动力学模型在一定条件下是可以应用于文蛤的富集动力学研究的，仍需要进一步开展不同条件下实验研究分析。

Kinetic study on the bioconcentration of heavy metals Cu and Pb in Meretrix meretrix under the condition of sediment exposure

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.