在沉积物暴露条件下2种海洋贝类对Cu、Pb 的富集动力学研究

首次通过构建海水-底泥-生物体体系,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)和缢蛏(Sinonovacula constricta)对Cu、Pb的生物富集实验,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,得到了文蛤和缢蛏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、富集平衡浓度CAmax、生物学半衰期B1/2等动力学参数。拟合结果得到的Cu、Pb各动力学参数分别为:文蛤K1为4.63—69.41,K2为0.05—0.08,CAmax为9.83—40.57,BCF为60.77—1444.56,B1/2为9.09—14.43;缢蛏K1为4.27—122.92。K2为0.05—0.07。CAmax为5.12—32.84。BCF为65.68—2112.02。B1/2为9.81—14.15。对模型的拟合优度检验结果显示,在沉积物暴露条件下文蛤和缢蛏对重金属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;CAmax均随着外部水体金属暴露浓度的增大而增大;文蛤和缢蛏对Cu富集能力大于Pb;Cu在文蛤和缢蛏体内的生物学半衰期B1/2大于Pb;理论平衡状态下文蛤和缢蛏体内Cu、Pb的含量CAmax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,实验结果表明在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和缢蛏的富集动力学研究的,但仍需要进一步开展在不同条件下实验研究分析。

KINETIC STUDY ON THE BIOCONCENTRATION OF Cu AND Pb IN TWO KINDS OF MARINE BIVALVE MOLLUSCS UNDER THE CONDITION OF SEDIMENT EXPOSURE

The kinetic parameters of the absorption process on accumulation and elimination of heavy metals Cu and Pb in Meretrix meretrix and Sinonovacula constricta were investigated under the condition of sediment exposure based on an established water-sediment-organism system.The kinetic parameters of bioconcentration were obtained by nonlinear curve fitting from the semi-static two-compartment model,including uptake rate constant(K1),elimination rate constant(K2),bioconcentration factor(BCF),and biological half-life(B1/2).The modeling results showed that K1 ranged from 4.63 to 69.41,K2ranged from 0.05 to 0.08,CAmax ranged from 9.83 to 40.57,BCF ranged from 60.77 to 1444.56,B1/2 ranged from 9.09 to 14.43 in M.meretrix,K1 ranged from 4.27 to 122.92,K2ranged from 0.05 to 0.07,CAmax ranged from 5.12 to 32.84,BCF ranged from 65.68 to 2112.02 and B1/2 ranged from 9.81 to 14.15 in S.constricta,respectively.It was found that the metal concentration were fitted to the two-compartment model,and 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 the uptake rate constant(K1) and bioconcentration factor(BCF) of M.meretrix and S.constricta generally decreased with the increase of heavy metal exposure concentration in ambient seawater,and so as the CAmax,the bioaccumulation ability order for the two heavy metals was Cu>Pb,the biological half-life(B1/2) of Cu was longer than those of Pb,the maximal content in the organism(CAmax) at the theoretic equilibrium increased and was basically and directly proportional to increasing metal concentration in the outside 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 and S.constricta,but required further experimental research and analysis under different conditions.