镉在两种经济贝类体内富集与排出的动力学研究

Dynamics Studiesg on Accumulation and Elimination of Cadmium by Two Economic Shellfishes

以太平洋牡蛎(Crassostrea gigas)和文蛤(Meretrix meretrix)2种经济贝类为试验生物,通过半静态暴露染毒的方法研究了2种贝类对镉离子(Cd2+)的35d富集和30d排出规律。实验结果表明:太平洋牡蛎和文蛤对镉都有很强的富集性,吸收速率与Cd2+浓度呈正相关,2种贝类对镉的排出速度较慢。应用双箱动力学模型,通过非线性拟合得到了2种贝类对镉的吸收速率常数k1、排出速率常数k2、生物学半衰期B1/2、生物富集因子BCF等动力学参数,K1和BCF与镉浓度呈负相关,CAmax与镉浓度呈正相关,在水体中镉浓度相同的情况下,太平洋牡蛎对镉的富集能力高于文蛤,CAmax大小顺序为太平洋牡蛎>文蛤;随着水体中镉浓度的增大,太平洋牡蛎和文蛤对镉的排出速率常数k2逐渐增大,B1/2逐渐减小。

To investigate regularities of accumulation and elimination ot caammm ko J -y nomic shellfishes, Meretrix rneretri3c, Crassostrea gigas were exposed to semi-static toxic water for 35 d or 30 d, and then Cd2＋ levels in vivo were determined, respectively. The results showed that all of two shellfishes could concentrate Cdz＋ strongly and the abosorption rates had positive correlations with Cd2＋ concentrations in culture media. By comparison, the elimination rates of two shellfishes were al most lower. The parameters including absorption rate （kl）, elimination rate （ka）, bioconcentration fac tor （BCF） and biological half life （B1/2） were obtained from nonlinear fitting curve based on double box dynamic model. Both kl and BCF were negatively related to Cd2＋ concentration, whereas there was a significant positive correlation between the maximal Cd2＋ content in vivo （C）and Cdz＋ concentration in culture media. At the same Cd2＋ level in media, accumulation capacities o two shellfishes followed the order as C. gigasM, meretril＇, and the order of C was C. gigasM, meretrix. With the in creasing of Cd2＋ concentration in media, the parameters of k2 for both C. gigas and M. meretricr in creased gradually, while B1/2 reduced gradually.