喀斯特环境质量变化的自然与人文过程特征——贵州喀斯特河流的地球化学研究

GYIG OpenIR > 研究生 > 学位论文

	喀斯特环境质量变化的自然与人文过程特征——贵州喀斯特河流的地球化学研究
其他题名	Characterization of Natural and Anthropogenic Processes Responsible for Karst Environmental Quality Changes- Geochemical Study of Karst Rivers in Guizhou
	韩贵琳
	2002
学位授予单位	中国科学院地球化学研究所
学位授予地点	中国科学院地球化学研究所
学位名称	博士
学位专业	地球化学
关键词	河水化学碳酸盐岩主元素 Sr同位素微量元素重金属元素
摘要	该论文选择贵州喀斯特地区的典型河流为研究对象,利用化学质量平衡、同位素和微量元素地球化学研究手段,定量计算了流域物理侵蚀速率和化学风化侵蚀速率及其对大气CO<,2>消耗的影响,探讨了河流水化学特征与人为活动、气候、地形、岩性等因素之间的关系,并对流域中的化学物质（主元素、稀土元素、重金属元素）循环过程进行时间和空间上的示踪研究,揭示喀斯特生态环境中水/岩（土壤）作用、水/粒界面作用对化学物质地球化学循环过程的控制机理及其环境效应特征,辨识了人为作用和自然过程对流域质量变化的相对影响.
其他摘要	Rivers are the important natural agencies for the erosion, transport and sedimentation of Earth's surface materials. The formation and evolution of rivers is the result of comprehensive action of specific geotectonic setting and bio-climate. On the geological and hydrological scales, rivers are the important loci of fresh water and CO_2 cycling on a global scale. The water chemical and geochemical characteristic features of rivers are a manifestation of the extent of surface weathering and denudation in response to climatic change, topography, and rocks and minerals. So far as the regional and global environmental problems are concerned, water erosion and soil loss and the deficiency of fresh water resources are directly related to the rivers. In the carbonate rock-distributed regions of Guizhou Province, where the karst environment has been strongly differentiated, the processes of weathering and erosion of surface rocks and soils there must possess their own unique features, and they would necessarily exert great impact on the surface environmental system. In this paper some typical rivers in the karst regions of Guizhou Province have been selected as the objects of study. By making use of chemical mass equilibriums and isotope and trace element geochemical approaches, the rates of physical erosion and chemical weathering and their influence on the exhaustion of atmospheric CO_2 for the basin systems have been calculated on a quantitative basis. Meanwhile, the relations are discussed between the water chemical characteristics of the rivers and human activities, climate, topography, and lithological character and tracing investigations, both in time and in space, are conducted on the processes of cycling of chemical substances (major elements, REE, heavy elements) in an attempt to disclose water/rock (soil) interaction, reactions at the water/particle interface, the mechanism controlling the geochemical cycling of chemical substances and environmental effects in the karst eco-environment so as to take us closer to the understanding of the relative influence of human activities and natural processes on environmental quality and its changes in the basin system. The following conclusions have been drawn: 1 Geochemistry of rainwater in the region of Guiyang Atmospheric input is the middle-reaches source of river substances. So rainwater chemical study is the basis for hydrogeochemical investigations of rivers and also is the prerequisite for discriminating the source of river substances. In this study twenty-two rainwater samples were collected from the region of Guiyang almost in the past three years and were analyzed for their chemical composition and isotope geochemical composition. Thus, the following conclusions are drawn: Ca~(2+) is the principal cation in rainwater in the region of Guiyang, which accounts for 64%-87% of the total cations; the sum of Ca~(2+) and Mg~(2+) accounts for 78%-96% of the total cations; SO_4~(2+) accounts for 28%-94% of the total anions; SO_4~(2+)and NO~3 are the major ions that determine the acidity of rainwater and their sum accounts for 77%-99% of the total anions. SO_4~(2+) in rainwater has three principal sources: marine- facies input accounts for 0.2%, that brought about by rock/soil chemical weathering accounts for 57.6%, and that produced by human activities accounts for 42.2%. The Sr concentrations of rainwater in the region of Guiyang vary from 0.02 u mol/L to 0.33 u mol/L. ~(87)Sr/~(86)Sr ratios vary over a small range (0.707934-0.709080). The ~(87)Sr/~(86)Sr isotopic composition is controlled mainly by human activities. In terms of element ratios and Sr isotopic composition it has been confirmed that the solutes in rainwater from Guiyang are predominantly derived from human activities, coming net are the continental input and marine input. In some cases marine input can be negligible. 2 Water chemical characteristics of river water and chemical weathering/erosion rates Water chemical and isotopic studies have been conducted of river waters from the Wujiang drainage system and the Yuanjiang drainage system during river water rising and falling seasons and the results take us closer to the following understandings: (1) Chemical composition of river water during water falling season: Excluding the three water samples from the Qingshui River which winds its way through clastic rock strata (TZ~+=0.43 -l.lmeq/L), the total cation concentrations of river water vary within the range of 2.1-6.3 meq/L. Ca~(2+) and Mg~(2+) are the major cations in the river water, accounting for more than 80% of the total in most river water samples. However, the three samples from the Qingshui River have higher K~+ + Na~+ concentrations. HCO_3~- is the most predominant anion in river water. River water samples from the Qingshui River have the lowest HCO~3 concentrations as well as the lowest TDS. NC_3 is a subordinate anion. The SO~2_4 concentrations of river water samples from the Wujiang, Qingshui and Wuyang rivers are estimated at 0.58, 0.23 and 0.10, respectively. SO~2_4+ NC_3 account for 90%-97% of the total anions. River water samples collected during water rising seasons also have similar characteristics. The water chemical and geochemical characteristics of rivers in the karst regions of Guizhou Province are controlled mainly by the solubility of carbonate rocks under subtropical moist climate conditions. That is to say, carbonate rock dissolution/ precipitation equilibrium is an important factor affecting the water chemistry of rivers. Our river water samples are high in Ca and Mg and alkalinity relative to those from Asia and other regions. The variation of major element concentrations along the river courses is dependent on the chemistry of rocks and soils distributed along the river courses, and mineral composition and physical and chemical weathering in the basin systems. (2) Researches on the concentrations of major elements, especially anions, in river water in the karst regions of Guizhou Province and their controlling factors have revealed that the studied river water samples are relatively enriched in SO_4~(2+), and there is a remarkable positive correlation between SO2%/Na+ and NQ"3/Na+. SO SO_4~(2+)/Na~+ and NO~3/Na~+ ratios are relatively high and ~(87)Sr/~(86)Sr ratios are relatively low in the river water. At the same time, the direct measurements of waste water indicated that the waste water has relatively low 87Sr/86Sr but relatively high SO SO_4~(2+)/Na~+ and NO_3/Na~ ratios. Since there is no evaporite in the basin systems, it is deduced that both, SO % and NO'3 would probably be input by atmosphere, though some SO2% would come from combustion of coal and oxidation of sulfide. Rivers in the. karst.regions, of Guizhou Province have been far less polluted than those of many developed countries. The extent of industrial pollution of rivers in the Wujiang drainage system of Guizhou is far greater than that in the Yuanjiang drainage system, but the extent of agricultural pollution of rivers in the Yuanjiang drainage system is much greater than that in the Wujiang drainage system. This situation is consistent with the fact that the areas along the Wujiang drainage system are more industrially developed than those along the Yuanjiang drainage system. Having influenced by climate, lithological character, topography and human activities in the drainage systems,
页数	159
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/3598
专题	研究生_研究生_学位论文环境地球化学国家重点实验室
推荐引用方式 GB/T 7714	韩贵琳. 喀斯特环境质量变化的自然与人文过程特征——贵州喀斯特河流的地球化学研究[D]. 中国科学院地球化学研究所. 中国科学院地球化学研究所,2002.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
LW008401.pdf（3512KB）			暂不开放	--	请求全文