恒河-布拉马普特拉河系统沉积物粘土矿物组成和重金属浓度及其对沉积物来源和人类活动的指示意义
文献类型：学位论文
| 作者 | MD HAFIJUR RAHAMAN KHAN |
| 答辩日期 | 2019 |
| 授予单位 | 南海海洋研究所 |
| 导师 | 刘建国 |
| 关键词 | 粘土矿物，重金属，物质来源，恒河 - 布拉马普特拉河-梅格纳河河流系统，孟加拉盆地 |
| 学位名称 | 硕士 |
| 学位专业 | 海洋地质 |
| 其他题名 | Clay mineral compositions and heavy metal concentrations in sediments of the Ganges-Brahmaputra river system and their implications in sediment sources and human activities |
| 英文摘要 | A total of 132 surface sediment samples from the Ganges-Brahmaputra-Meghna (GBM) river system were collected from Bangladesh during Nov-Dec, 2017. All the samples were used for clay minerals analyses with X-ray diffraction (XRD) in order to demonstrate the variation of clay mineral assemblages in the sediments from upstream to downstream for the major rivers of the Bengal Basin (BB) and to verify the validity of clay minerals as an essential index for sediment provenance in the Bay of Bengal after these sediments are discharged into the neighboring Bay of Bengal. The results show that the clay mineral assemblage in the GBM river system consists dominantly of illite (average 66%), with smaller amounts of chlorite, smectite and kaolinite with the respective contents of 17%, 8% and 8%. In the Ganges River sediments, smectite is diagnostic with a higher content (23%) than that in the Brahmaputra (2%) and the Surma-Meghna (SM) River (1%); however, the SM River sediments contain higher chlorite contents (21%) and illite percentage (77%) is comparatively higher in the Brahmaputra River sediments. Downstream percentages of smectite in the Ganges River increase significantly, but the kaolinite percentages in sediments of the SM River increase slightly. Due to the continuous mixture of firstly the Brahmaputra River discharge and then the SM River discharge (the sediment contributions are estimated to be approximately 50% and 45%, respectively), the clay mineral assemblages in sediments of this river system change greatly, e.g., smectite percentages decrease from 23% in the Ganges River to 8% in the GBM River through a intermediate value of 12% in the Ganges-Brahmaputra confluence river. Overall, the sediments of the BB river system are characterized by strong physical erosion with weak hydrolysis of Fe-Mg rich felsic rocks of Himalayan sources, while the smectite in the Ganges River originates from the low-temperature (pedogenic processes) chemical weathering of the Himalayan and the Deccan Trap basaltic sources and forms in the Indo-Gangetic flood plain.Meanwhile, trace metals (Sc, Cr, Co, Ni, Cu, Ga, Ge, Nb, Mo, Cd, In, Hf, Ta, W, Tl, Pb, Bi, Th and U) in some selected sediments samples of GBM river system are also measured by inductively coupled plasma mass spectrometry (ICP-MS) after proper treatment to evaluate the heavy metal contamination and its anthropogenic influence. The average concentration levels of most of the heavy metals (except Mo and Tl) are above the background reference of the crustal and shale values. Several contamination indices including the contamination factor, pollution load index, enrichment factor, and geo-accumulation index, and multivariate statistical analyses indicate that sediments of the GBM river system are polluted by Bi, Th, Ta, Cd, Nb, Pb, In and U. Among the four individual rivers, the Brahmaputra River and Ganges-Brahmaputra confluence River (GB) contain higher concentrations of heavy metal than the sediments of the Ganges and Surma-Meghna rivers, which may be caused by the effect of local municipal discharge, industrial or urban wastes, and ferry crossing activities. |
| 源URL | [http://ir.scsio.ac.cn/handle/344004/18119]  |
| 专题 | 南海海洋研究所_学位论文（硕士） |
| 推荐引用方式 GB/T 7714 | MD HAFIJUR RAHAMAN KHAN. 恒河-布拉马普特拉河系统沉积物粘土矿物组成和重金属浓度及其对沉积物来源和人类活动的指示意义[D]. 南海海洋研究所. 2019. |
入库方式： OAI收割
来源：南海海洋研究所
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