饮用水中余氯对大型蚤的急性和慢性毒性

目前我国饮用水生产过程中普遍采用氯消毒,在去除一些有害微生物的同时,会形成一定浓度的余氯。为了监测余氯对用于在线监测的水生生物产生的毒性效应,讨论了饮用水中余氯对大型蚤的急性和慢性毒性。当余氯为0.16 mg/L时,大型蚤24 h存活率为100%,48 h存活率为90%;当余氯达到0.32 mg/L时,大型蚤48 h存活率为30%。在最小致死剂量(MLD=0.16 mg/L) 暴露下,40 d慢性毒性结果显示水中余氯对大型蚤生长和生殖影响显著。因此,可用于实现在线连续监测过量投加后水中高浓度的余氯。而当大型蚤用于毒性的在线生物监测(如突发性事故监测), 或用于监测水质大幅度变化时,应考虑首先消除水中余氯对动物行为生态的影响。

Acute and chronic toxicities of residual chlorine in drinking water on Daphnia magna

Online water quality bio-monitoring on continuous watching of the behavior alternations of aquatic animals has been proposed recently for the in-site information of the water quality variations. Because chlorination has been widely used for disinfection of drinking water and a certain concentration of residual chlorine should be maintained in the water, its influence on the survival and growth of watching animals in bio-monitor should be considered. In this paper, the acute and chronic toxicities of chlorine on Daphnia magna were discussed. The results showed that 100% and 90% survival of Daphnia magna could be reached in 24 h and 48 h when the animal was exposed to 0. 16 mg/L of chlorine. When the level of residual chlorine increases to 0. 32 mg/L, survival in 48 h was only 30% . When exposed to the minimum lethal dose (MLD) of 0.16 mg/L for 40 d, significant influences could be observed in terms of the growth and reproduction parameters. Therefore it was concluded that, on one side, Daphnia magna could be used in the bio-monitor for the purpose of monitoring variations of residual chlorine in water. On the other hand, the influence of residual chlorine on Daphnia magna should be avoided when the monitoring purposes are set for toxicants other than chlorine, or for emergency accidences, which may cause large variation of water quality.