三疣梭子蟹体内苯并[a]芘的富集动力学

Kinetics of benzo[a]pyrene bioconcentration in Portunus trituberculatus

采用半静态双箱动力学模型研究三疣梭子蟹（Portunus trituberculatus）对苯并[a]芘（benzo[a] pyrene,BaP）的生物富集,通过对富集与排出过程中三疣梭子蟹体内BaP的动态监测,并对监测结果进行非线性曲线拟合,得到三疣梭子蟹的吸收速率常数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BaP的各动力学参数分别如下：K1为14.67 ～ 26.08、K2为0.09～0.14、CAmax为9.31 ～73.35、BCF为163.00～196.29、B1/2为4.95 ～7.70 d.对模型的拟合优度检验结果显示,在BaP暴露条件下三疣梭子蟹对BaP的生物富集数据符合双箱动力学模型,模型的拟合优度良好.比较结果得出：三疣梭子蟹对不同浓度的BaP吸收速率常数K1及生物富集系数BCF基本随外界水体中暴露浓度的增加而降低;排出速率常数K2与外界水体暴露浓度无明显关系;理论平衡条件下生物体内BaP含量CAmax随着外界水体中BaP暴露浓度的增加而增大,且基本成正相关.实验结果表明BaP暴露条件下双箱动力学模型在一定条件下是可以应用于三疣梭子蟹的富集动力学研究的.

With the increase of marine traffic and industrial sewerage discharge, polycyclic aromatic hydrocarbon （ PAHs ） pollution has become more serious. Benzo[ a ] pyrene （ BaP ） is one of the most carcinogenic PAHs. It is widely distributed in seawater, and has been used as a representative study of PAHs. Portunus trituberculatus is widely cultured in the coast of China as an important economic bivalve. We adopted seawater-organism systems, studied the absorption and release of benzo[ a ] pyrene in P. trituberculatus using a semi-static two-compartment kinetic model by dynamic detection of BaP concentrations in crabs and results of goodness-of-fit test model to provide references for prediction of ecological risks of BaP. In this experiment, three trestments were set up to investigate the kinetic parameters of bioconcentration （including uptake rate constant （K1 ）, elimination rate constant （K2 ）, bioeoncentration factor （BCF）, and biological half-life （B1/2 ） ） by 15 days of enrichment experiments and 15 days of release. Results suggested that BaP exposure were correlational to BaP contents in P. trituberculatus, and the treatment of 0.45g · L-1 group showed obvious differences compared with the control group （ P 〈 0.05 ）, while the BaP contents were not significantly different between 0. 05 μg· L-1 group and the control group （P 〉 O. 05 ）. During the enrichment-elimination trials, results showed the law of bell curve among all treatments. Besides, the modeling results showed that Kx ranged from 14.67 to 26.08, K2 ranged from 0.09 to 0.14, the maximal contents （CAmax） ranged from 9.31 to 73.35, BCF ranged from 163.00 to 196.29, and BI/2 ranged from 4.95 to 7.70 d. We found that the BaP concentration data conformed to the two-compartment model, and good agreement was found between the predicted and observed BaP concentrations using the goodness-of-fit test. Results also indicated that K1 and BCF of P. trituberculatus generally decreased with the increase of BaP exposure concentration in the ambient seawater, K2 had no significant relationship with the BaP concentrations in the seawater, and the maximal contents in the organism at the theoretic balance increased and was basically proportional to the increase of BaP concentration in the water. The experimental results showed that the semi- static two-compartment kinetic model could well fit the bioconeentration of BaP in P. trituberculatus. The enrichment experiments showed that P. trituberculatus had a strong enrichment capability for BaP, the uptake rate constant and elimination rate constant reduced with the increase of seawater concentration. The maximal contents increased with the growing of BaP concentration. During the release experiments, with the increase of time the elimination rate constant became slow and the BaP in organism gradually reduced to the level close to the control group. Results showed that two-compartment model could be applied in the study of bioconeentration kinecties of Portunus trituberculatus under BaP exposure.