沉积物中重金属Pb和Cd对河蚬的毒性效应研究

以河蚬为受试生物,以存活率、呼吸抑制率为测试终点,研究了沉积物和上覆水中重金属Pb、Cd对底栖生物的毒性效应,并探讨了沉积物中酸挥发性硫化物(acid volatile sulfide,AVS)和同时提取金属(simultaneously extracted metals,SEM)对重金属生物有效性的影响。结果表明,沉积物中Pb、Cd对河蚬致死效应较低,当Pb、Cd浓度分别为400、100 mg獉kg-1,连续暴露21 d时,致死率低于20%;沉积物中Pb、Cd对河蚬14 d的呼吸抑制率EC50分别为519和151 mg獉kg-1;上覆水中Pb和Cd离子浓度较低,对生物毒性效应贡献可以忽略;SEM/AVS值和生物呼吸抑制率有着明显的线性相关性,当SEMPb/AVS1,SEMCd/AVS0.6时,重金属对河蚬有明显的毒性效应。

Toxicity of Pb/Cd-Spiked Freshwater Sediments to Corbicula fluminea

The toxicities of Pb and Cd in fresh water sediment and overlying water were evaluated using Corbicula fluminea as test organisms. The toxicity endpoints were survival and respiratory inhibition rate. The objectives of this research were to investigate the toxic effects of the two heavy metals on benthic organisms and the effects of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM). The results indicated that Pb/Cd displayed weak lethal toxicity to Corbicula fluminea with mortality less than 20% even exposed at 400 and 100 mg?kg-1 for 21 d. The values of EC50 of respiratory inhibition rate of Pb and Cd in the 14 d tests were 519 and 151 mg?kg-1, respectively. The contribution of overlying water to the total toxicity was negligible due to the low metal concentrations in the overlying water. A good correlation between the toxic effects of Pb and Cd on benthic organisms and SEM/AVS was observed. When SEMPb/AVS>1 and SEMCd/AVS>0.6, the two metals displayed obvious toxicities to Corbicula fluminea.