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Articles by H.M. Zakir
Total Records ( 3 ) for H.M. Zakir
  H.M. Zakir , Naotatsu Shikazono and Kazuo Otomo
  The geochemical distributions of cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb) and zinc (Zn) were examined in sediments collected from Old Nakagawa River (NR), Tokyo, Japan. A widely used 5-step sequential extraction procedure was employed for the fractionation of the metals and the concentrations were measured in the liquid extracts by inductively coupled plasma mass spectrometry (ICP-MS). The association of Cd (76-98%) and Zn (48-67%) were found highest with AEC (adsorbed/exchangeable/carbonate) phase, Cu (45-60%) and Pb (44-73%) with amorphous Fe oxyhydroxide phase and the maximum fractionation of Cr was in both crystalline Fe oxide (12-60%) and amorphous Fe oxyhydroxide phase (15-60%). For retention by amorphous Fe oxyhydroxide minerals, the observed stoichiometric gradient was: 1.52 for Cu, 1.23 for Pb, 2.25 for Cr and 3.09 for Zn. Corresponding values for association with crystalline oxides and sulphides and organics were an order of magnitude greater than those for amorphous oxyhydroxide, indicating a greater affinity of trace metals for these phases. The total concentration ranges of Cd, Cr, Cu, Pb and Zn in NR sediments were 2.86-16.95, 551.7-3953.1, 340.6-1565.3, 136.9-385.9 and 931.4-3650.1 µg g-1, respectively. The observed order of potential trace metal mobility in the aquatic system was: Cd>Zn>Pb>Cu>Cr. Organic carbon contents in sediment samples were comparatively high (mean 5.48%) and the X-ray diffraction (XRD) study detected the presence of several clay minerals, those are likely to be major host of trace metals in sediments. The sediments of NR was considered to be polluted on the basis of unpolluted sediments and geochemical background values with respect to Cd, Cr, Cu, Pb and Zn. According to the enrichment factors (EFc), most of the sites have several times higher values of trace metals than the standard. The study revealed that the pollution in sediments of NR could be linked to anthropogenic activities such as industrialization, urbanization, deposition of industrial wastes and others.
  Shaila Sharmin , H.M. Zakir and Naotatsu Shikazono
  Problem statement: Urban river sediment pollution due to Zn and Pb is a serious problem in all over the world. The source and level of Zn and Pb pollution in sediments of Nomi River of Ota Ward, one of the most industrialized areas in Tokyo, Japan is still lacking. Approach: The present study focused on Rare Earth Elements (REEs) and geochemical partitioning of Zn and Pb in sediments of 19 sampling sites of Nomi River in order to examine the mobility pattern. The amounts of Zn and Pb in the liquid extract of 5 (five) geochemical phases were measured by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the concentrations of REEs in sediments were determined by using X-ray Fluorescence Spectroscopy (XRF). Results: Speciation data indicate dominant labile fraction of Zn, which is related to the presence of several anthropogenic influence of the investigated area. Enrichment Factor (EFc) and Index of geoaccumulation (Igeo) value were compatible with the result, which confirm pollution status of Zn. Environmental risk of Zn and Pb were also evaluated using the Risk Assessment Code (RAC) and sequential extraction results and found Zn poses high to very high risk (34-59), whereas Pb poses low to medium environmental risk (0-19). Conclusion: The mean values of REEs and other minor elements were lower or very close to average shale and Japanese river sediment value but Sr, Sn, Zr and Sb contents were little bit higher than average Japanese river sediment values. Anthropogenic activities, prevalent in the study area play a key role in the accumulation of Zn and Pb in aquatic system. Early warning on the sediment pollution to respective authorities help in preserving the aquatic system from further degradation of the river.
  M.A.H. Chowdhury , R. Begum , M.R. Kabir and H.M. Zakir
  Microbial respiration (CO2 evolution),inorganic SO4-S and available P were monitored in a S deficient soil amended with dhaincha, cowdung and rice straw @ 1 g per 50 g soil during 30 days incubation. A basal dose of 250 μg N, 200 μg P and 250 μg K g -1 soil was applied. Dhaincha showed the highest decomposition rate and rice straw showed the lowest rate, while that of cowdung was intermediate. After 30 days of incubation, 53, 17 and 39% C was decomposed from cowdung, rice straw and dhaincha, respectively. Decomposition was also found to be related to its nutrient status (C:N:S ratio). Considerable S mineralization was recorded in dhaincha and cowdung amended soil and attained the maximum at 15th day (13.8 μg g -1S) and 30 (9.8 μg g -1 S), respectively. During rice straw decomposition S was immobilized markedly. Application of plant and animal residues caused significant increase in P mineralization. Net mineralization was 95.5, 87.6 and 50.8 μg P g -1 soil in dhaincha, cowdung and rice straw amended soil, respectively.
 
 
 
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