Jain C K
National Institute of Hydrology, Roorkee 247 667, India.
Water Res. 2004 Feb;38(3):569-78. doi: 10.1016/j.watres.2003.10.042.
The pollution of aquatic ecosystem by heavy metals has assumed serious proportions due to their toxicity and accumulative behavior. The toxicity and fate of the water borne metal is dependent on its chemical form and therefore quantification of the different forms of metal is more meaningful than the estimation of its total metal concentrations. In this study fractionation of metal ions on bed sediments of River Yamuna has been studied to determine the eco-toxic potential of metal ions. The investigations suggest that copper have a tendency to remain associated with residual, reducible and carbonate fractions. The Risk Assessment Code reveal that about 30-50% of lead at most of the sites exist in exchangeable fraction while 30-50% of cadmium at almost all the sites is either exchangeable or carbonate bound and therefore comes under the high risk category and can easily enter the food chain. Most of the copper is in immobile fraction at Delhi while at other sites, a sizable portion (10-30%) is found in carbonate fraction thus posing medium risk for the aquatic environment. Fractionation pattern of zinc shows low to medium risk to aquatic environment.
由于重金属的毒性和累积特性，其对水生生态系统的污染已达到严重程度。水中金属的毒性和归宿取决于其化学形态，因此对不同形态金属进行定量分析比估算其总金属浓度更具意义。在本研究中，对亚穆纳河河床上沉积物中的金属离子进行了分级研究，以确定金属离子的生态毒性潜力。调查表明，铜倾向于与残余、可还原和碳酸盐部分结合。风险评估代码显示，在大多数站点，约30 - 50%的铅以可交换形态存在，而在几乎所有站点，30 - 50%的镉要么是可交换的，要么是与碳酸盐结合的，因此属于高风险类别，很容易进入食物链。在德里，大部分铜处于不可移动形态，而在其他站点，相当一部分（10 - 30%）存在于碳酸盐部分，因此对水生环境构成中等风险。锌的分级模式显示对水生环境的风险为低到中等。
