| 印度河-雅鲁藏布缝合带地热活动与流域砷异常关系研究 |
| 王慧
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| 导师 | 李社红
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| 2013
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| 学位授予单位 | 中国科学院研究生院
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| 学位授予地点 | 北京
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| 学位名称 | 硕士
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| 学位专业 | 矿物学、岩石学、矿床学
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| 关键词 | 砷富集
印度河-雅鲁藏布缝合带
地热活动
砷来源
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| 摘要 | 西藏雅鲁藏布与森格藏布(又名狮泉河)流域是藏南和藏西阿里地区最为重要的农牧城镇饮用水源，地处印度河—雅鲁藏布缝合带(Indus-Tsangpo Suture Zone)，分别是布拉马普特拉河（Brahmaputra）及印度河（Indus）的上游流域，其下游地区存在典型、严重的地下水水型砷中毒病区。雅鲁藏布与森格藏布流域分别作为这两条河流的源头区域，有可能为下游的高砷地下水提供一定的物质来源，但其特殊的地理环境条件使该区域有关砷的研究仍较薄弱。 此前的研究发现西藏雅鲁藏布与森格藏布流域存在砷超常富集的现象，并对其分布特征和来源进行了初步分析，认为其可能与该区盐湖或地热水有关，但缺乏形成该区砷异常来源充分的地球化学或其它更为直接的证据。为了更详细的了解两大流域砷异常的分布及确切来源，在课题组前期工作的基础之上，作者于2011年8月-9月赴西藏雅鲁藏布和森格藏布流域进行了更为详细系统的野外调研及热泉、河湖、地下水、沉积物等环境样品的采集，并通过在关键河段的断面设置追踪其异常来源。通过详细的野外调研及样品分析，获得以下认识： 1) 研究证实了雅鲁藏布江流域河水砷异常主要出现在日喀则以西及拉萨河上游部分支流河段，而狮泉河流域大部分河段都存在河水砷异常现象。 2) 对雅鲁藏布和森格藏布流域不同水体砷的含量分布有了新的认识。由于各种水体的砷含量变化范围都较大，用中位数值应该更能反映其总体水平。不同水体砷含量中位数依次为：盐（咸）湖水(20396 μg/L, n=1)＞热泉水(1782.06 μg/L, n=7)＞森格藏布河水(27.66 μg/L , n=14)＞雅鲁藏布河水(7.93 μg/L, n=31) ＞淡水湖水（5.16 μg/L, n=9）＞井水及自来水(4.17 μg/L, n=10)。与此前研究结果类似，该区盐（咸）湖水及热泉水都高度富集砷。不同的是，该区淡水湖、井水及自来水样品，除了个别受热泉或高砷河水的影响而升高外，大部分样品的砷含量都较低，显示为正常含量水平。 3) 河流、湖泊等沉积物对水中的砷起吸附作用，其吸附等温线符合Freundlich方程，具体为lgG = 0.4749lgc + 1.6077。 4) 众多直接或特征元素地球化学间接证据证明，该区砷异常主要源于印度河-雅鲁藏布缝合带两侧强烈的地热活动带来的高砷地热水。并推断该流域中缺乏直接来源证据的热玛江、尼热木布河等高砷河段也应该是由于地热活动带来的异常。 5) 西藏雅鲁藏布及狮泉河流域地热活动导致的砷异常已在部分地区影响到了居民的饮水安全问题，有关部门应引起重视。 |
| 其他摘要 | The rivers of Singe Tsangpo (alternate named Shiquan R.) and Yarlung Tsangpo are the most important drinking water sources in western and southern Tibet. They located in the Indus-Tsangpo Suture Zone and are the upstream of Indus and Brahmaputra rivers respectively. Some arsenic may be transferred to the downstream through the rivers. The studies on arsenic in this area are still lack for the severe conditions. The previous studies showed that arsenic enrichment existed in the drainages of Yarlung Tsangpo and Singe Tsangpo. The salt lakes and geothermal water were thought to be the sources. However, the evidences of geochemistry or other direct evidences were lacked. For this reason, more detailed investigations were carried out in August and September 2011 and some results were listed as follows. 1. It was confirmed that arsenic enrichment existed in most of Singe Tsangpo River and the upstream of Lhasa River and Yarlung Tsangpo River of west Xigaze. 2. Updating knowledge on arsenic distribution in different waters of this area was got. The median of arsenic concentrations in different water from high to low were salt lake (median 20396μg/L, n=1),hot spring (median 1782.06 μg/L, n=7), stream water of Singe Tsangpo River (median 27.66 μg/L , n=14), stream water of Yarlung Tsangpo River (median 7.93 μg/L, n=31), freshwater lake（median 5.16 μg/L, n=9）, dug well and tap water (median 4.17 μg/L, n=10). Similar as formal previous studies is that arsenic enrichment displayed in salt lakes and hot springs. However, most samples of freshwater lakes, dug wells and tap waters in this area are in lower and normal arsenic concentrations except for a few samples are enriched results from high arsenic river or hot springs. This is much different to the previous viewpoints. 3. Arsenic in the sediments of rivers and lakes were mainly adsorption from the water and could be fitted as Freundlich equation: lgG = 0.4749lgc + 1.6077. 4. Lots of direct and indirect geochemical evidences showed that the abnormity of arsenic in this area were resulted from the intense geothermal activities in Indus-Tsangpo Suture Zone. It could be deduced that the arsenic abnormity in some stream segments, such as Rema and Niremubu River, should be results from geothermal activities although there were no direct evidences. 5. Drinking water in some parts of the region were contaminated by the higher arsenic geothermal water and should be brought to the forefront. |
| 学科领域 | 环境地球化学
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| 语种 | 中文
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| 文献类型 | 学位论文
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| 条目标识符 | http://ir.gyig.ac.cn/handle/352002/5861
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| 专题 | 研究生_研究生_学位论文
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推荐引用方式
GB/T 7714 |
王慧. 印度河-雅鲁藏布缝合带地热活动与流域砷异常关系研究[D]. 北京. 中国科学院研究生院,2013.
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