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Distribution And Chemical Speciation Of Select Transition Metals In The Waters Of River Yamuna, New Delhi

B.Anjan Kumar Prusty, E.P.Jagadeesh, P.A.Azeez, D.K.Banerjee

Select metals Fe, Mn, Cu, Pb, Zn, Ni and Cr were investigated in the water samples collected from river Yamuna. Although free metal ion concentrations of Cu, Pb and Cd were probed using ion selective electrodes, they were found below the detection limits of the electrodes. Among the total dissolved metals, zinc was found to be highest, i.e. 304.85g/l at najafgarh drain, while lead was seen in the lowest concentration(0.05g/l) at site ramghat, the entry point of the river into New Delhi. Lead concentration ranged between 0.05 to 1.37g/l. The lowest level was found at ramghat and highest level at nizamuddeen bridge and okhla barrage. As expected Zn, Fe and Mn were seen in very high concentrations compared to the other elements namely Cu, Cr, Ni and Pb. In each site, the variation among the metal concentrations was highly significant. Similarly each of these metals also differed significantly(LSD, P<0.05) among the sampling sites. At down stream sites the percentage concentrations of chelex-labile metals, particularly Fe, Mn and Cu were lower than that of the upstream sites. This is attributed to the varied nature and amount of colloidal matter in the waters at these sites. Copper in the river water differed from the other metals in its behavior towards chelex-resin, probably for its strong association with the organic films on Fe and Mn colloids.