液氯对摇蚊幼虫的毒效试验及影响因素

针对摇蚊幼虫(红虫)在沉淀池中大量孳生这一难题,以蒸馏水为试验水样,研究了液氯对摇蚊不同龄期幼虫的毒性效果(24h),并考察了pH值、有机物含量、氨氮以及藻类含量等因素对毒性效果的影响.结果表明:随龄期增长摇蚊幼虫对液氯的耐受性不断增强,液氯对4龄摇蚊幼虫的24h半致死浓度(LC₅₀)为3.39mg/L;低pH值、高藻类含量有助于提高液氯对摇蚊幼虫的毒性效果;在水质中性条件下,有机物含量提高使摇蚊幼虫的死亡率降低,在不同氨氮浓度下,液氯对摇蚊幼虫的毒性效果差别较大.生产原水和沉淀池水的对比试验表明:在不同投加量下,原水中4龄摇蚊幼虫接触24h死亡率均高于沉淀池水中摇蚊幼虫死亡率.

Toxicity and Influencing Factors of Liquid Chlorine on Chironomid Larvae

The excessive propagation of Chironomid larvae (red worm) in the sedimentation tanks is a difficult problem for the normal function of waterworks. The toxic effect of liquid chlorine on the different instar larvae of Chironomid was studied using distilled water as test sample. Furthermore, the effect of pH value, organic matter content, ammonia nitrogen, and algae content on toxicity of liquid chlorine was observed. The results show that the tolerance of Chironomid larvae to liquid chlorine is strengthened with the increase in instar. The 24h semi-lethal concentration (LC₅₀) of liquid chlorine to the 4th instar larvae of Chironomid is 3.39mg/L. Low pH value and high algae content are helpful to improve the toxic effect of liquid chlorine to Chironomid larvae. In neutral water body, the increase in organic matter content results in the decrease in the death rate of Chironomid larvae. The toxicity of liquid chlorine differs greatly in different concentrations of ammonia nitrogen. The death rate of the 4th instar larvae of Chironomid in raw water is higher by contrast with that in sedimentation tanks water for 24h disposal with various amount of liquid chlorine.