浅层地下水系统污染敏感性及其内在净化作用研究

Groundwater contamination and remediation are one of the priority research topics for hydrogeology and Earth Science studies. In the past several decades, industrialization ad urbanization have caused world wide depletion of groundwater resource and degradation of water quality. The threat related to groundwater contamination has become a major concern for governments and the public in many countries. .More and more data have shown that groundwater systems have the property of intrinsic remediation or self-regulating capacity of hindering the accumulation of contaminants or degrading them, through physical, chemical or biological processes. This contradicts with the general trend of increase in pollutant loads on groundwater systems and therefore a lot of efforts have been made to study Vulnerability of shallow groundwater systems to contamination and their intrinsic remediation of contaminants..In this research project, several sites from central-eastern China (Beijing, Wuhan, Hunan, Shandong, Shanxi, etc.) were selected for studying the mechanisms and spatial-temporal variations of intrinsic remediation of shallow groundwater systems with different hydrogeological structures and matrixes, kinetic modeling of relevant hydrogeochemical processes such as sorption, biodegradation, redox, and dissolution/precipitation, and numerical modeling of reactive transport of contaminants. GIS-based vulnerability assessment was made to improve or propose models and mapping methods to provide information for decision-making concerning groundwater resource exploitation, protection and environmental planning..Based on a lot of field and laboratory work, the following academic advances have been made by combining international collaboration, graduate student thesis work, academic exchange with research work. (1) The spatial-temporal variation of organic contaminants: The water quality data, of both surface and subsurface waters from Wuhan, a set of data of trace organic contaminants in particular, have been obtained. The analytical techniques of trace organic contaminants in groundwaters have been developed. The distribution of major organic contaminants in groundwaters from Beijing has been surveyed and can be summed up as follows: the organics in phreatic aquifers are more detectable and enriched than in confined aquifers and the transitional zones between the two types of aquifers. The spatial distribution of chlorinated hydrocarbons is in dots. The heavily polluted area is about 8km2,with trichloroethene and tetrachloroethene as the major contaminants, mostly higher than 10μg/L. (2) Shallow groundwater vulnerability assessment models and applications: groundwater vulnerability analysis and mapping are new concepts and frontiers for hydrogeology and environmental studies. The relevant research work in China has just been started and therefore proposal of assessment index system is both theoretically and practically important. In order to protect groundwater resources, delineation of areas vulnerable to human activities has become an important way for environmental management. Two new models, namely DRAMIC model and MLPI model, were proposed and successfully applied in Wuhan, Hubei and Datong, Shanxi. (3) Experimental studies of intrinsic remediation in groundwater systems: degradation of benzene and toluene was found to occur simultaneously with reduction of nitrate, as shown in microcosm environments of enriched and transferred cultivation. Toluene is more degradable than benzene and facilitates benzene degradation. Batch experiments comparing the degradation of chlorohydrocarbons by zero valence iron, zeolites and bentonite under different conditions help further understand the degradation mechnism and the optimal degradation conditions. Sorption and precipitation are frequently occurring intrinsic remediation processes in groundwater systems. By studying the specific sorption of fluoride by a red soil from Xinzhou, Shanxi, the working method of studying anion sorption has been improved. Experiments were also made to study the so

以中国东部为重点研究区，开展浅层地下水系统的内在净化作用机理、有机污染物生物降解反应动力学及相关的变价元素污染物氧化还原分带规律精细观测与实验、起内在净化作用的地球化学过程定量模拟以及地下水污染敏感度分级和制图方法研究。其成果不仅有助于解决地下水污染理论研究中的重大问题，而且可为地下水资源开发和保护提供科学依据。