H. M. Zakir

Geochemical distribution of trace metal pollutants in water and sediments of downstream of an urban river

A study was conducted to investigate the trace metal pollution of water and sediments of downstream of Tsurumi River, Yokohama, Japan. Twenty samples of water and sediments were collected from the river starting from Tokyo bay side up to the junction point of the Yagami River. Results show that the mean concentrations of chromium, cupper and nickel in water greatly exceed (>100 times) the surface water standard. The concentration of molybdenum and lead was also higher than standard values while iron and manganese was lower than that of surface water standard. The mean concentration of zinc, cupper, cadmium, lead, chromium, vanadium, bromine and iodine was 381.1, 133.0, 1.0, 40.8, 102.9, 162.0, 71.5 and 10.6 μg/g sediments, respectively and was greatly exceed the average worldwide shale concentrations and average Japanese river sediment values. However, mean concentration of arsenic, nickel and strontium was 11.0, 36.6 and 164.6 μg/g sediments, respectively which was lower than the average shale value. Other analyzed trace metals, including barium, zirconium, rubidium, yttrium, tin, antimony, cesium, lanthanum, cerium, praseodymium and neodymium were detected in river sediments; the concentration of which was close to the Japan’s river sediment average values. Pollution load index values of the sites of the studied area ranged from 1.24 to 7.65 which testify that the river sediments are polluted. The PLI value of the area was, however, high (6.53) as the concentration of trace metals like zinc, cupper, cadmium, lead and chromium were very high and were the major pollutants.

Heavy metals contamination in water and sediments of an urban river in a developing country

Water and sediment samples were collected from 20 location of the Buriganga river of Bangladesh during Summer and Winter 2009 to determine the spatial distribution, seasonal and temporal variation of different heavy metal contents. Sequential extraction procedure was employed in sediment samples for the geochemical partitioning of the metals. Total trace metal content in water and sediment samples were analyzed and compared with different standard and reference values. Concentration of total chromium, lead, cadmium, zinc, copper, nickel, cobalt and arsenic in water samples were greatly exceeded the toxicity reference values in both season. Concentration of chromium, lead, copper and nickel in sediment samples were mostly higher than that of severe effect level values, at which the sediment is considered heavily polluted. On average 72 % chromium, 92 % lead, 88 % zinc, 73 % copper, 63 % nickel and 68 % of total cobalt were associated with the first three labile sequential extraction phases, which portion is readily bioavailable and might be associated with frequent negative biological effects. Enrichment factor values demonstrated that the lead, cadmium, zinc, chromium and copper in most of the sediment samples were enriched sever to very severely. The pollution load index value for the total area was as high as 21.1 in Summer and 24.6 in Winter season; while values above one indicates progressive deterioration of the sites and estuarine quality. The extent of heavy metals pollution in the Buriganga river system implies that the condition is much frightening and may severely affect the aquatic ecology of the river.

Sources, spatial variation, and speciation of heavy metals in sediments of the Tamagawa River in Central Japan

Sediments of the Tamagawa River in central Japan were studied to explain the spatial variation, to identify the sources of heavy metals, and to evaluate the anthropogenic influence on these pollutants in the river. Sediment samples were collected from 20 sites along the river (five upstream, four midstream, and 11 downstream). Heavy metal concentrations, viz. chromium, nickel, copper, zinc, lead, cadmium, and molybdenum, in the samples were measured using inductively coupled plasma-mass spectroscopy. The chemical speciations of heavy metals in the sediments were identified by the widely used five-step Hall method. Lead isotopes were analyzed to identify what portion is contributed by anthropogenic sources. The total heavy metal concentrations were compared with global averages for continental crust (shale) and average values for Japanese river sediments. The mean heavy metal concentrations were higher in downstream sediments than in upstream and midstream samples, and the concentrations in the silt samples were higher than those in the sand samples. Speciation results demonstrate that, for chromium and nickel, the residual fractions were dominant. These findings imply that the influence of anthropogenic chromium and nickel contamination is negligible, while copper, zinc, and lead were mostly extracted in the non-residual fraction (metals in adsorbed/exchangeable/carbonate forms or bound to amorphous Fe oxyhydroxides, crystalline Fe oxides, or organic matter), indicating that these elements have high chemical mobility. The proportion of lead (Pb) isotopes in the downstream silt samples indicates that Pb accumulation is primarily derived from anthropogenic sources.

Assessment of Metal Pollution in Lower Torag River in Bangladesh

The study was conducted to assess the metal pollution levels in water and sediments of lower Torag River in Bangladesh. Industrial wastewaters and urban sewage from the Tongi municipal and industrial area directly discharge to this part of the rivers without any sorts of treatment. Fourteen samples each of water and sediment were collected and the distance, in between the samples was about 300 m. The results showed that the metal concentrations in the water samples greatly exceeded the standard values for the surface water quality. 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 were higher than the standard shale values. Although the geoaccumulation index (Igeo) for most of the heavy metals lie 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 good to excellent positive co...

Zinc Pollution Level in Sediments of Old Nakagawa River, Tokyo, Japan

Sediments from Old Nakagawa River in Tokyo were collected and analysed for the study of zinc (Zn) pollution level in the less than 63 μm grain size fraction. The geochemical fractionation of Zn was examined with a widely used sequential extraction scheme and the concentrations were measured in the liquid extracts by inductively coupled plasma mass spectrometry (ICP‐MS). A certified reference stream sediment sample (JSd‐2) provided by the Geological Survey of Japan was also analysed using the same procedure as a check. The association of Zn was comparatively higher with carbonatic and oxide phases, and the ranges were 333–1811 and 269–1114u2009μgu2009g−1, respectively. The sediments of Old Nakagawa River was considered to be polluted on the basis of unpolluted sediments and geochemical background values with respect to Zn. According to the Zn enrichment factors (EFc), the most points have several times higher values than the standard. The geoaccumulation indexes for most of the sampling points also indicate Zn con...