Xia Xinghui, Wang Ran
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, People's Republic of China.
Environ Toxicol Chem. 2008 Jan;27(1):119-25. doi: 10.1897/06-643.1.
Mechanisms for the effects of sediment on the biodegradation of organic compounds in the aquatic environment are not clear. In this research, effects of sediment characteristics on biodegradation kinetics of chrysene and benzo[a]pyrene were studied by inoculating polycyclic aromatic hydrocarbon (PAH)-degrading bacteria. Because water and PAHs can pass a polytetrafluoroethylene membrane yet bacteria and sediment cannot, a membrane experiment was performed to compare the biodegradation rates of PAHs in water and at the sediment-water interface, providing direct evidence that the PAH biodegradation rate is enhanced by the presence of sediment. Biodegradation of PAHs in water-sediment systems was fitted to zero-order kinetics; the order of biodegradation rate in water-sediment systems with different sediment was fine silt > clay > coarse silt. Biodegradation of PAHs in water-sediment systems occurred mainly at the sediment-water interface. According to membrane experiment results, when the biodegradation kinetics was fit to a zero-order equation, the maximum specific growth rates of bacteria (1/d) at the sediment-water interface were approximately three- to fourfold those in the water phase. Furthermore, the associated mechanisms regarding the effect of sediment characteristics were analyzed by investigating the process of bacterial growth and the distribution of bacteria and PAHs between water and sediment phases.
沉积物对水生环境中有机化合物生物降解作用的机制尚不清楚。在本研究中，通过接种多环芳烃（PAH）降解细菌，研究了沉积物特性对芘和苯并[a]芘生物降解动力学的影响。由于水和多环芳烃可以透过聚四氟乙烯膜，而细菌和沉积物不能，因此进行了一项膜实验，以比较水中和沉积物 - 水界面处多环芳烃的生物降解速率，提供了沉积物的存在会提高多环芳烃生物降解速率的直接证据。水 - 沉积物系统中多环芳烃的生物降解符合零级动力学；不同沉积物的水 - 沉积物系统中生物降解速率的顺序为细粉砂＞黏土＞粗粉砂。水 - 沉积物系统中多环芳烃的生物降解主要发生在沉积物 - 水界面。根据膜实验结果，当生物降解动力学符合零级方程时，沉积物 - 水界面处细菌的最大比生长速率（1/d）约为水相中的三到四倍。此外，通过研究细菌生长过程以及细菌和多环芳烃在水相和沉积物相之间的分布，分析了沉积物特性影响的相关机制。
