褶牡蛎对水体中重金属铜和镉的富集动力学特性

Kinetic study on the bioconcentration and elimination of heavy metals Cu and Cd in Crassostrea plicatula

中文关键词: 褶牡蛎  重金属  双箱模型  富集动力学  规格

英文关键词: Crassostrea plicatula  Heavy metals  Two conpartment kinetic model  Bioaccumulation kinetics  Size

中文摘要:

      以褶牡蛎Crassostrea plicatula为研究对象，应用半静态双箱模型室内模拟了大、小两种规格褶牡蛎对重金属Cu、Cd的生物富集释放过程。通过对富集与释放阶段褶牡蛎体内重金属含量变化进行非线性拟合，得到了褶牡蛎对重金属Cu、Cd的生物富集曲线及富集动力学参数。结果表明，1）富集阶段褶牡蛎对Cu、Cd的生物富集系数BCF及吸收速率常数 k1 随着外部水体中重金属暴露浓度的增大而减少，理论平衡状态下生物体内重金属含量随外部水体中重金属暴露浓度的增大而增大；2）释放阶段褶牡蛎对重金属Cu、Cd的吸收速率常数k1随富集阶段外部水体中Cu、Cd暴露浓度的增大而减小，褶牡蛎体内Cu的生物学半衰期B1/2随富集阶段外部水体中Cu暴露浓度的增大而延长，Cd的生物学半衰期与Cd暴露浓度的关系无明显规律性；3）褶牡蛎对Cu的富集能力和排出能力均强于Cd；4）大规格褶牡蛎对Cu、Cd的富集能力均强于小规格，而褶牡蛎规格大小对于其体内Cu、Cd的排出作用的影响不显著。

英文摘要:

      In the present study, accumulation and elimination processes of two metals(Cu,Cd) in Crassostrea plicatula were simulated by using the two-conpartment kinetic model. A semi-static system was maintained throughout 36d exposure period in different concentrations of heavy metals. Kinetic parameters of bio-concentration were obtained from the two-conpartment kinetic model by nonlinear curve fitting for the two periods respectively, including uptake rate constant(k1), elimination rate constant(k2), bioconcentration factor(BCF), and biological half-life(B1/2). It was found that the metal concentration and elimination were well fittted to the two-conpartment model by using the goodness-of-fit test. The results indicated that: (1) In the uptake period, the uptake rate constant and bioconcentration factor of heavy metals generally decreased with the increase of heavy metal concentration in ambient seawater, and maximal content in the organism(CAmax)at the theoretic equilibrium increased with the increase of heavy metal concentration in ambient seawater; (2) During the elimination period, the uptake rate constant of heavy metals and the B1/2 of Cu in C. plicatula were decreased with the increase of heavy metal concentration in ambient seawater (uptake period), and the B1/2 of Cd in C. plicatula had no obvious trend with the exposure concentration; (3)The Cu bioaccumulation ability of C. plicatula was higher than Cd; (4)The bioaccumulation ability of large-size C. plicatula was stronger than small-size ones, indicating that the differences in size of C. Plicatula had no significant effect on the elimination of heavy metals .