1Laboratory of Geochemistry, Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Yokohama 223–8522, Japan.
2Department of Agricultural Chemistry, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.
*E-mails: zakirhm.ac.bau@gmail.com; sikazono@applc.keio.ac.jp
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A study was conducted to investigate the heavy metal contamination of water and sediments of Turag River at Tongi area in Bangladesh. Non treated urban sewage and industrial wastewaters from Tongi area affect this river water chemistry. Fourteen samples each of water and sediments were collected from both side of the river. The results showed that heavy metal concentrations in the water samples greatly exceeded the standard values for the surface water quality. A majority of heavy metals studied in the waters showed very poor correlation with each other. Organic carbon and clay content in the sediment samples were, in general, high (3.6 and 40.76%, respectively). The mean concentrations of Mn, Zn, Cr, Cu and Pb in the sediment samples (896, 111, 97, 49 and 24 μg g−1, respectively) were higher than the standard shale values. Although the geoaccumulation index (Igeo) for most of heavy metals lies below grade zero but according to Igeo class some points were moderately contaminated for Zn, Cu, Cr and Pb. About 40 – 50% heavy metals studied showed significant positive correlation with pH, EC and organic carbon of the sediments, but among the heavy metals of the water and sediments, only 13–14% of metals showed significant correlation coefficient with each others, indicating either their common urban origin or their common sink in the river system. The high metal contents in both water and sediment samples were found close to the industrial establishments and so the enhanced metal concentrations are related to the direct discharge of the industrial sewage and municipal wastes into the river.
Heavy metal, Turag River, Tongi, Bangladesh
