栉孔扇贝对镉的富集及释放规律的研究

Study of the Variation Behavior of the Accumulation and Elimination of Cd^(2+) in Chlamys farreri

通过暴露染毒方法研究了栉孔扇贝对镉离子(Cd2+)的35d富集与30d释放规律。结果表明:栉孔扇贝对镉有很强的富集性,体内的镉含量与暴露溶液里的Cd2+浓度呈正相关;栉孔扇贝对镉的释放速率随着暴露水体中镉浓度的增加而减慢。应用双箱动力学模型,通过非线性拟合得到了栉孔扇贝对Cd2+的吸收速率常数k1随着外部水体中镉浓度的增大而减小,生物富集系数BCF则随着外部水体中镉浓度的增大而减少。当镉浓度为0.05mg/L时BCF仅为3 730,而当镉浓度为0.000 5mg/L时BCF达到1.79×1011。平衡状态下栉孔扇贝体内镉含量(CAmax)随着水体中镉浓度增加急剧下降,与水体中镉浓度呈负相关;排出速率常数k2、生物学半衰期B1/2与低浓度镉无明显相关性,随着镉浓度的增大k2显著降低而B1/2显著增大。验证了双箱动力学模型适用于栉孔扇贝对Cd2+的生物富集与释放规律研究。

The 35 days accumulation and 30 days elimination of cadmium were studied in Chlamys farre- ri in cadmium exposure experiments. The results showed that Chlarnys farreri had a strong character in enriching cadmium and the bioaccumulation amount in tissues increased with the addition of cadmium con- centration in seawater. Furthermore, the speed of cadmium elimination decreased.with the addition of cadmium concentration in seawater. Applying a kinetic model of two-compartment, the kinetic parameters was obtained through the nonlinear fitting. The constant of absorption rate k1decreased with the concentration of cadmium in seawater. The bioconcentration factors（BCF） which decreased with the concentration of the cadmium was merely 3 730 when the cadmium concentration in the seawater was 0. 05 mg/L. However, the BCF reached 1.79 × 10^11 when the cadmium concentration in the seawater was 0. 000 5 mg/L. The concentration of the cadmium in Chlamys farreri （CAm.x） showed a negative correlation with the concentration of the cadmium, which decreased rapidly with the concentration of the cadmium in seawater at equilibrium state. The elimination rate constant k2 and the biological half-life B1/2 had no obvious relationship with the low concentration of the cadmium while B1/2increased significantly with the concentration of the cadmium which was opposite to the k2. It approved that the two-compartment kinetic model was appropriate for the accumulation and elimination experiments of the cadmium in Chlamys farreri.