当前世界环境

Considering the significance of heavy metal pollution in aquatic system bioaccumulation of heavy metals in two species of tadpoles namelyClinotarsus alticola和Leptobrachium smithicollected from tea gardens of Barak valley, Assam was studied. Aquatic life is affected by heavy metal pollutants present in water as well as in sediment. The result of the study revealed that the concentration of iron, chromium, cadmium and lead in water samples was higher than the permissible limit of 0.3, 0.05, 0.003, 0.01 mg/L respectively but that of copper and zinc concentration was within the maximum permissible limit of 2 mg/L and 3 mg/L (WHO, 2005).The accumulation pattern of different heavy metals in different organs viz., intestine, liver and tail was studied.Overall the metal burden in different organs ofClinotarsus alticola和Leptobrachium smithiwas in the order of liver>tail>intestine. Liver had highest accumulation of metals while intestine accumulated the least.Iron (Fe) was highly and zinc (Zn) was the least accumulated metal in both the tadpoles. The accumulation of heavy metals might be due to tea plantation influx water, domestic and associated anthropogenic activities.