以南方鲇(Silurus meridionalis Chen)幼鱼(19.75 ± 0.12 g)为研究对象,以K2Cr2O7作为毒物源,在(27.5 ± 0.5)℃条件下分别进行了急性暴露和慢性暴露的毒理效应实验.通过急性暴露实验,测得该种鱼的96 h半致死浓度值(96 h LC50)为56.24 mg/L.在水体Cr浓度分别为0(对照组)、0.937 mg/L(96 h LC50的1/60)和1.875 mg/L(96 h LC50的1/30)条件下,进行了为期8周的慢性暴露实验.结果表明,实验鱼体的特定体重生长率、肥满度和肝脏指数随着Cr浓度的升高而显著降低,肾脏指数随Cr浓度的升高而显著升高;两个Cr浓度组鱼体的蛋白质和能量密度均显著低于对照组,(1/30)96 h LC50浓度组鱼体的脂肪含量显著低于对照组,而前者的水分含量则显著高于后者.两个Cr浓度组鱼体的静止代谢率均显著高于对照组.经过8周水体Cr暴露处理后,实验鱼体的各器官组织中Cr的累积含量均显著高于对照组,其累积含量的顺序均为肾>鳃>肝>肠>全鱼>脑>肌肉;(1/60)96 h LC50和(1/30)96 h LC50浓度组的肾脏的Cr累积含量显著高于其他组织,肌肉的Cr累积含量均显著低于其他组织;鳃组织中Cr含量相对于对照组的增加幅度大大高于其他组织的增幅.%Laboratory tests were conducted on juvenile of Silurus meridionalis Chen (19.75 g±0.12 g) during acute and chronic exposures to potassium dichromate (K2Cr2O7) at constant water temperature (27.5 ℃±0.5 ℃).The median lethal concentration in 96 hours (96 h LC50) of Cr to the southern catfish was 56.24 mg/L in the acute exposure experiment.In the chronic exposure experiment, fish was exposed to Cr at a series of concentrations of 0 (control group), 0.937 and 1.875 mg/L, which were equivalent to approximately 0, 1/60 and 1/30 of 96 h LC50, respectively for 8 weeks.The chronic experiment results indicated that the mortality of the fish increased with increasing waterborne chromium concentrations.The specific weight growth rate, condition factor and hepatosomatic index all decreased with the increasing Cr exposed concentration.Meanwhile, the kidney index increased with the increasing Cr concentration.The content of crude protein and energy density of the fish exposed to Cr was significantly lower than that in the control group.The content of fat in 1.875 mg Cr/L group was significantly lower than the control, and the water content in the control was significantly lower than the other groups.The resting metabolic rate in two Cr exposure groups were significantly higher than that in the control.The contents of chromium in organs after 8-week exposure could be ordered from higher to lower as following: kidney > gill > liver > intestines > whole fish > brain > muscle.The Cr content in kidney in both exposure groups were significantly higher than that in the other tissues, while the Cr content in muscle in both Cr exposure groups was significantly lower than that in the other tissues.The Cr content in the gill tissue compared with the control group was higher than that in other tissues.
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