| There is lack of water resources in the city of Beijing. In the city, available quantity per person is less than 400m3 annually. The South-to-North Water Diversion Project is of magnitude for country plan. After the Middle Rout Project (Beijing part) is finished, the quantity of water supply for Beijing areas will be added 10×108m3 every year. In addition to water shortage for capital being eased up, the exiting dynamic balance of water resources must be influenced and accordingly the environmental balance relating to water resources must be influenced.After the project, the groundwater discharge will be reduced designedly. On the one hand water resources will be recovered, but on the other hand it is possible that salinity in aeration zone will be dissolved into groundwater and its hydrochemistry components will be changed with water level rising and aeration zone being narrower.Starting with water-rock interaction, considering the complexity of groundwater quality change mechanism, adopting the indoor soil-column test, hydrochemistry interactions between groundwater and rocks in the soakage layer of aeration zone are analyzed in the study, adsorption of soil particle and cation exchange etc included. It is studied that development trends of hydrochemistry components are caused by water level rising and aeration zone being marinated. And the evolution laws of hydrochemistry components with different lithology and time are analyzed. In long geological age, the hydrochemistry components were formed by integration of various functions. These acting functions are related with groundwater environment. Environment is made of a great many factors, such as physical geography (climate, topography, hydrology etc), geology (lithology, geological structure), hydrogeology (hydrodynamic force condition, palaeo-hydrogeological condition), physical chemistry, physics, biology and man-made factors. Those factors have a great impact on the change of groundwater quality. During substance exchange and energy transfer between aquifer and outside, hydrochemical field in aquifer is also changed. Therefore, this study aims to the change of groundwater quality in superficial layer influenced by aeration zone being narrower through field sampling and indoor soil-column test. Thereby the resolve capability of anion and cation is analyzed in superficial layer. At the same time the course of transfer and transform between every environmental factor in water and anion or cation in soil is studied. It is mainly focused on the change of Ca2+ and mg2+ concentration with time. The evolution law of hydrochemistry components is also analyzed with different lithology and time.Sampling spots are located in the regions that water level maybe greatly rise again because of restrict discharge after the South-to-North Water Diversion Project and that that are probably contaminated in the future, i.e. Liaogongzhuang in the southwest of Beijing city and Langfa District of Daxing. The sampling depth is controlled in the zone of water level rising again in the future, i.e. 1.5~2.0m above present phreatic water table. Getting soil sample, local groundwater is gotten as water sample at the same time. Through the contrast analysis,there are conclusions as follow: During long interaction between groundwater and aeration zone, Ca2+ and mg2+ in groundwater are adsorbed to some extent by soils in aeration zone. Content of Ca2+ and mg2+ in groundwater are reduced so that it is benefit to decreasing its mineralization. The change in content of Ca2+ and mg2+ is affected by ion exchange and adsorption. The main factors influencing adsorption are the size of adsorbent particle, ion valence, ion radius and ion content. For capability of soils' adsorption to Ca2+ and Mg2+, the smaller particle diameter is, the higher it is; the higher content of clay mineral is, the higher it is; the higher content of organic matter is, the higher it is. The common natural adsorbents are clay mineral (montmorillonite, kaolinite, hydromica etc), organic...
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