菲和镉单一及复合污染条件下在毛蚶体内的富集动力学研究

采用室内半静态双箱动力学模型实验,研究了菲和镉单一及复合污染条件下在毛蚶(Anadara subcrenata)体内的生物富集,通过对富集与释放过程中毛蚶体内菲和Cd的富集量进行非线性曲线拟合,获得了菲和Cd单一及复合污染条件下在毛蚶体内的吸收速率常数k1、释放速率常数k2、生物富集因子BCF、生物半衰期B1/2和平衡状态下最大富集量CA max等动力学参数。实验结果表明,菲和Cd在实验前期富集速率较高,8 d以后富集速率减缓,释放阶段与富集阶段相似。毛蚶对菲的BCF值为37.80,远大于Cd的BCF值13.12,且生物半衰期时间更长,菲更容易在生物体内富集。菲和Cd联合暴露条件下,在毛蚶体内的CA max和BCF值均大于单一作用,说明二者同时暴露时,毛蚶对菲和镉的吸收富集均有所增强。实验模型拟合度较好,输出值和实测值之间无显著性差异,拟合方程和拟合参数可信。

Kinetics of Bioconcentrations of Phenanthrene and Cadmium in Tissues of Anadara subcrenata under Single and Joint Exposures

The bioconcentrations of phenanthrene and cadmium (Cd) in the tissues of Anadara subcrenata under single and joint exposures were investigated using the semi-static two-compartment kinetic model. The kinetic parameters, including uptake rate constant (k₁), elimination rate constant (k₂), bioconcentration factor (BCF), biological half-life (B_1/2) and maximum bioaccumulation at equilibrium (C_Amax), were determined with nonlinear fitting of the time-course phenanthrene and Cd bioconcentration and elimination data. The bioconcentration rates of phenanthrene and Cd were faster during the early stage and slowed down after eight days. The temporal trend of the elimination rate was similar to that of bioconcentration. Phenanthrene possessed a higher BCF (37.80) than did Cd (BCF: 13.12), suggesting that phenanthrene could more easily cause bioconcentration in Anadara subcrenata. In the presence of both phenanthrene and Cd (i.e. joint exposure), C_Amax and BCF increased for both compounds as compared to the condition where only one compound was present (i.e. single exposure). The combination of phenanthrene and Cd thus enhanced their bioconcentrations in Anadara subcrenata. The modeled data are not significantly different from the measured ones, validating the semi-static two-compartment model in studying the kinetics of bioconcentrations of phenanthrene and Cd by Anadara subcrenata.