水体中铅对长江上游6种鱼类的急性中毒效应

为了检验不同鱼类对水体中铅(Pb)的耐受能力的差异,在控制实验室水体的温度(27.5±0.2)℃、硬度(10.0±0.5)Ca CO3mg/L、p H值(7.0±0.1)等条件下,测定了草鱼(Ctenopharyngodon idellus)(22.13±0.31)g、鲫(Carassius auratus)(25.36±0.36)g、南方鲇(Silurus meridionalis)(21.28±0.20)g、团头鲂(Megalobrama amblycephala)(21.39±0.20)g、胭脂鱼(Myxocyprinus asiaticus)(22.34±0.32)g和中华倒刺鲃(Spinibarbus sinensis)(21.36±0.21)g这6种鱼经水体Pb 96 h急性暴露后的半致死浓度(96 h LC50),以及Pb在鱼体内的累积量。结果发现,水体中的Pb对草鱼、鲫、南方鲇、团头鲂、胭脂鱼和中华倒刺鲃的96 h LC50值分别为3.73、11.59、6.59、3.27、0.33和3.00 mg/L;6种鱼对Pb的耐受能力依次为:鲫南方鲇草鱼团头鲂中华倒刺鲃胭脂鱼。同种鱼中Pb暴露致死鱼体和未死亡鱼体内的Pb累积量均分别随着暴露的浓度的升高而增加;在相同Pb浓度处理条件下,同种鱼中死亡鱼体的Pb累积量高于未死亡鱼体。水体硬度和鱼体重会影响重金属Pb对鱼类的96 h LC50。较高硬度水体暴露的Pb对鱼体的毒性较小,同种鱼体重较大的个体对重金属Pb的耐受能力较强。同种鱼不同时间段死亡鱼体中的Pb累积量没有显著性差异;每种实验鱼因Pb暴露致死群体的平均Pb累积量均分别高于其未死亡鱼群体,除南方鲇外,其余5种鱼二者间的差异达到了显著性水平。

Acute toxic effect of water-borne lead on six fishes from the upper reaches of the Yangtze River

In order to estimate the tolerances of 6 fishes from the Yangtze River to the toxicity of water-borne lead(Pb), median lethal concentration of Pb for 96 hours(96 h LC50 ) in Ctenopharyngodon idellus, Carassius auratus, Silurus meridi-onalis, Megalobrama amblycephala, Myxocyprinus asiaticus and Spinibarbus sinensis were tested at same water temperature (27. 5 ± 0. 2)℃, hardness (10 ± 0. 5)mg/L CaCO3 and pH (7. 0 ± 0. 1). The values for 96 h LC50 in the 6 fishes were 3. 73, 11. 59, 6. 59, 3. 27, 0. 33 and 3. 00 mg Pb/L, respectively. The results suggested that the tolerances for Pb tox-icity were different among the six species and the order was C. auratu >S. meridionalis >C. idellus >M. amblycephala >S. sinensis>M. asiaticus. In each species the lead accumulation of the tested fish body increased with increasing Pb con-centration, and the accumulation in the dead fish was higher than that in the survivor when exposed to a same Pb concen-tration. The values for 96 h LC50 can be influenced by the water hardness and the weight of fish. Pb was less toxic in har-der water to fish and larger fish was more tolerant to Pb toxicity. The lead accumulation in the dead fish was not influenced by its death time for the same species. The mean value of lead content of the dead fish in each species was higher than that of the survivors, and except for S. meridionalis the differences were significant between the dead and the survivor in the oth-er 5 species.