| Hohhot city, located in northwest of north China, TuMoChuan plain of central InnerMongolia, is the capital of Inner Mongolia Autonomous Region. In this paper, harmfulelements in groundwater is the main research object, based on the analysis of geochemicalfeatures of soil and groundwater in the study area, combining with harmful elementsformation mechanism experiments, explores the migration, transformation and enrichmentregularity of harmful elements such as arsenic in groundwater in the study area, reveals theformation mechanism of harmful elements such as arsenic in groundwater and providesbasis for reasonable development of water resources, protection of the local groundwaterenvironment and avoiding the toxic elements lead to provide theoretical basis for thedisease risk.Through the analysis and research, the main following progresses having been reachedare shown as follows.(1) Hydro chemical characteristics of high harmful elements in groundwater have beenrevealed. Harmful elements in the shallow groundwater are As, F, Cd, Cr, Hg, et.al. Highcontent elements are As and F. High arsenic groundwater areas are mainly distributed in thethe center of the Daheihe River fluvial basin and the areas nearby the Hasuhai Lake. Highfluorine groundwater areas are mainly distributed in the the center of the Tuoketuo countryand the west of Helingeer country.(2) The distribution characteristics of arsenic in soil are analyzed. The main soil typesin the study area are light yellow or beige clay and very fine sand, the content of arsenic insoil is8.64μg/g, and is more in clay because of the larger specific surface area and thevertical electrostatic adsorption ability of clay minerals. Arsenic are mainly distributed in0~35meters depth, and high arsenic points are been existed whenever oxidation orreduction environment.(3) The environment evolution of high harmful elements groundwater in the study areahas been analyzed. Because of the palegeographic environment of lacustrine facies, coupledwith the closed structure conditions in high harmful elements areas, the reductiveenvironment formed. In addition, the drought climate, flat terrain, fine grain of aquifer,small hydraulic gradient, the lagging runoff, shallow groundwater, intense evaporation andintermittent irrigation have caused the increase of groundwater salinity, and the enrichment of trace elements such as arsenic and fluorine.(4) Soluble harmful elements in the soil have been studied for the first time, which isexperimented on the typical core soil samples, and analyzes the correlations of thedissolving elements. Experimental results verified the harmful elements arsenic andfluorine were taken away by low salinity water and migrated easily. In the process ofmigration and runoff, water salinity increases gradually, arsenic and fluorine elements usedto be fixed in groundwater were gradually dissolved in the sediment, as the timeaccumulated, the high arsenic and fluorine areas were gradually formed in the catchment’sarea of low-lying. |
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