东湖茶港排污口底泥对稀有鮈鲫的毒性

TOXICITY OF SEDIMENT IN CHAGANG SEWAGE ENTRANCE OF DONGHU LAKE ON GOBIOCYPRIS RARUS

以东湖茶港排污口底泥复溶水为试验相,采用96h急性毒性试验和胚胎—卵黄囊吸收阶段毒性试验方法,研究了东湖茶港排污口底泥对稀有的鮈鲫毒性。结果显示,高浓度的复溶水对稀有鮈鲫胚胎、仔鱼和幼鱼具有明显的毒性效应,而胚胎—卵黄囊吸收阶段更为敏感。随着复溶水浓度的增加,稀有鮈鲫受精卵孵化率降低,仔鱼畸形率增高、成活率降低、生长减慢;对胚胎—卵黄囊吸收阶段的NOEC、LOEC和MATC分别为12.5%、25%和17.68%;对幼鱼96h LC50为69.1%。本文的研究还表明,底泥经晾晒后毒性大幅降低,暗示恢复东湖通江状态并让水位自然涨落,可能有助于缓解污染、恢复生态环境。

Donghu Lake is a typical shallow lake in the northeast of Wuhan city.It has been badly polluted by point and area sources and becomes severely eutrophic since 1950s.Anterior studies have shown that high concentration of nutrients,heavy metal and organic contamination existed both in water and sediment.In order to repair the ecological environment,more attention is being paid to inner contamination after outer contamination is controlled.In the present study,toxicity of the sediment collected from a main sewage entrance of Donghu Lake was studied,using Gobiocypris rarus as experimental animal because this species is sensitive to many poisons and has been widely used in toxicology in China.In this study,96h acute toxicity test and embryo-yolk sac stage larva toxicity test were made on the elutriate phase of sediment.The result showed that high concentration of elutriate had obvious toxicity effect on embryo,yolk-sac larva and young of G.rarus.Dose-effect relations between the concentration of elutriate and hatching rate,abnormality rate,survival rate and growth were analyzed.As the concentration of the elutriate increasing,decreasing of hatching rate and survival rate,increasing abnormality rate,as well as delay on growth were observed.It was proved that toxicity test on embryo-yolk sac stage was more sensitive than the 96h acute toxicity test.The no observed effect concentration（NOEC）,the lowest observed effect concentration（LOEC） and the maximum acceptable toxicant concentration（MATC） for embryo-yolk sac stage were 12.5%,25% and 17.68%,respectively,while the median lethal concentration（LC50） for young was 69.1%.These results suggested that the embryo-yolk sac stage larva toxicity test of Gobiocypris rarus was a rapid,exact and sensitive test method and could be used in sediment toxicology in the future.Moreover,test on sundried sediment revealed that the NOEC was 100%,which was 8 times higher than that of fresh sediment.This result implies that toxicity of sediment could be reduced by solar radiation photodegradation.In the end,the authors suggest that Donghu Lake should be re-connected with the Yangtze River to let the water level fluctuate seasonally.It would be in favor of controlling pollution and repairing ecological environment because the exist of hydro-fluctuation land is helpful for solar radiation photodegradation and growth of aquatic plants.