Heavy metal status of sediment in river Cauvery,Karnataka |
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Authors: | K Venkatesha Raju R K Somashekar K L Prakash |
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Institution: | (1) Department of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran;(2) College of Agriculture and Natural Resources, Faculty of Natural Resources, University of Tehran, Karaj, Iran;(3) Graduate Faculty of Environment, University of Tehran, Tehran, Iran;(4) Parvaresh Alley, Daroopakhsh Street, 7915873389 Bandar Abbas, Iran |
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Abstract: | The purpose of this research work was to appraise extent of heavy metals in sediment and the degree to which its quality tainted
seasonally and spatially in river Cauvery. In this study, heavy metals such as Fe, Zn, Ni, Mn, Pb, Cu, Co, Cd and Cr were
analysed in sediments. Results were compared with sediment quality guidelines from various derived criteria. Twenty-five sampling
points were selected based on geographical proximity of agricultural fields and industrial discharges; river-tributary confluence
points; settlements located along the river bank; ritual and recreational activities. Sampling was done for the period of
3 years (2007 to 2009). Digestion of the samples was done by microwave-assisted digestion technique. Analysis was carried
out using flame furnace atomic absorption spectrophotometer, and results are expressed in micrograms per gram. The mean concentration
of Fe (11144 μg/g) followed by Mn (1763.3 μg/g), Zn (93.1 μg/g), Cr (389 μg/g), Ni (27.7 μg/g), Cu (11.2 μg/g), Pb (4.3 μg/g),
Co (1.9 μg/g) and Cd (1.3 μg/g) remained within the levels of sediment quality guidelines. Multivariate statistical techniques
such as principal component analysis and cluster analysis (CA) were employed to better comprehend the controlling factors
of sediment quality and spatial homogeneity among the stations. The sediment geo-accumulation index (Igeo) showed maximum value of Cd (2.69) and least value of Mn (−1.44). The geo-accumulation class (Igeo class) was in the sequence as follows: Cd>Zn>Pb>Cr>Cu>Co>Ni>Fe>Mn. Negative total geo-accumulation indices (Itot) revealed that mean concentration of heavy metals in the river bed sediment are lower than their respective shale values.
The statistical analysis of inter-metallic relationship revealed the high degree of correlation among the metals indicated
their identical behaviour during transport. This study concludes that insignificant geo-accumulation with metals except Cd
(moderate contamination), Pb and Zn (slight contamination) principally in downstream stretch may perhaps deteriorate the sediment
quality due to intensification anthropogenic influences. It also proves that extent of existing metal concentrations in sediments
of river Cauvery in Karnataka not exceeded the toxic limit, and there is no peril to the aquatic life. |
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