川中遂宁地区红层地下水水化学特征及主要离子来源分析

Analysis on Hydrochemical Characteristics and Origin of the Main Ions of Shallow Groundwater in Redbed of Suining Area, Central Sichuan Basin

四川红层区居民用水主要为就近开采的地下水,水质参差不齐,研究红层地下水水文地球化学特征,对于宜井区选择,红层水源地用水安全具有重要意义。利用在遂宁船山区采集的70组浅层地下水水样,采用数理统计分析、离子比例关系等方法,分析了红层浅层地下水水化学特征及主要离子来源,研究得出:区内地下水中阴离子以HCO3-(164.00~571.91 mg·L-1)为主,其次是SO42-(13.96~1 000.00 mg·L-1),阳离子以Ca2+(45.70~313.00 mg·L-1)为主,其中孔隙水的水化学类型主要为HCO3,SO4-Ca,SO4-Mg型,裂隙水以HCO3-Ca,Mg型与HCO3-Ca型为主;地下水中离子成分主要由岩石风化产生,来源于地层中的方解石、白云石、石膏、芒硝等矿物的风化溶解,蒸发浓缩、地下水酸碱环境及人类活动对地下水成分造成了一定的影响;浅层地下水质量以Ⅲ~Ⅳ类为主,污染物主要为TDS、Fe3+等原生污染,也存在NO3-、NO2-等人类活动污染;红层宜井区主要为平坝、丘坡坡脚及沟谷一带,为避免污染指标超标,井深不宜超过25m,远离养殖场、农厕等地下水易受人类活动污染的环境,防止鱼塘、农田等地表水进入井中。

The water used by residents in the red bed area of Sichuan province is mainly the groundwater extracted nearby,and the water quality is uneven.Therefore,the study on the hydrogeochemical characteristics of the red zone groundwater is of great significance for the selection of well-suited areas and the water safety of the red zone water source.Taking Suining Chuanshan district as an example,this paper analyzes the hydrochemical characteristics and main ion sources of the red shallow groundwater in suining district by means of mathematical statistical analysis,ion proportion relation and mineral saturation index of 70 groups of shallow groundwater samples collected. The results show that the anions in the groundwater of the study area are mainly HCO3-(164.00~571.91 mg·L-1),the second is SO42-(13.96~1 000.00 mg·L-1),the cations is Ca2+(45.70~313.00 mg·L-1);The ion composition in groundwater is mainly produced by rock weathering,and comes from the weathering and dissolution of calcite,dolomite,gypsum,mirabilite and other minerals in the strata,and at the same time evaporates and concentrates.The quality of shallow groundwater is mainly of type III^IV.The main pollutants are primary pollution such as TDS,Fe3+,and human activities such as NO3-,NO2-and so on.The suitable wells for red beds are mainly in the areas of flat dams,hillsides and valleys.In order to avoid exceeding the pollution index,the depth of wells should not exceed 25 m,and groundwater far away from aquaculture farms and agricultural latrines is vulnerable to human beings.Active pollution of the environment,prevent fish ponds,farmland and other surface water into wells.