大汶河流域中下游浅层地下水水化学特征及其影响因素

Hadrochemical Characteristics and Influencing Factors of Shallow Groundwater in the Middle and Lower Reaches of the Dawen River Basin

泰安市是黄河流域下游高质量发展的主战场,地下水是其重要的供水水源.为查明大汶河流域中下游地区浅层地下水水化学特征及其影响因素,采集浅层地下水80组,对其12项化学指标进行检测分析.综合运用数理统计、离子比值、水化学图解、饱和指数等方法系统地分析了水化学组分的空间分布、水化学特征,讨论了控制水化学组分的主要离子来源及其影响因素.结果表明:①大汶河流域中下游浅层地下水pH介于6.52~8.00之间,TDS(溶解性总固体)浓度介于364.00~2627.00 mg/L之间,以淡水、微咸水为主,由东向西沿着地下水流向逐渐升高;TH(总硬度)介于245.06~1235.02 mg/L之间,以硬水、极硬水为主.②地下水中阳离子以Ca^(2+)为主,阴离子无主导成分,以混合型为主,研究区内浅层地下水水化学类型较为复杂,以HCO_(3)-Ca型、HCO_(3)·SO_(4)-Ca型为主,同时出现了NO_(3)型水,建设用地水化学类型多达14种,其次为耕地(13种)和林地(6种).③地下水中主要离子来源于碳酸盐岩、硅酸盐岩的风化溶解,岩盐、石膏处于不饱和状态,方解石、白云石处于溶解沉淀的平衡状态.研究显示,大汶河流域中下游浅层地下水水化学特征主要受水岩相互作用控制,阳离子交替吸附作用较弱,同时也受到了农业和工业等人类活动的影响.

Tai′an City is the main battlefield for high-quality development of the Yellow River Basin,and groundwater is an important water supply source for Tai′an City.In order to determine the hydrochemical characteristics and influencing factors of shallow groundwater in the middle and lower reaches of the Dawen River Basin,80 groups of shallow groundwater were collected and 12 chemical indexes were detected.The hydrochemical characteristics and the spatial distribution of chemical components of shallow groundwater in the area were analyzed using mathematical statistics,ion ratio,hadrochemical diagram and saturation index.Moreover,the sources of major ions and influencing factors of hydrochemical components were discussed.The results indicated that:(1)The shallow groundwater in the study area was mainly freshwater and brackish water,with pH values ranging from 6.52 to 8.00 and the TDS values ranging from 364.00 mg/L to 2627.00 mg/L.Both the pH and TDS values raised along the groundwater flow direction from the east to west.The TH values were between 245.06-1235.02 mg/L,belonging to the category of hard water to extremely hard water.(2)The cation in groundwater was mainly Ca^(2+),while no anion was in a dominant position,indicating the anion was mainly mixed.The hydrochemistry types of shallow groundwater were relatively complex,mainly including HCO_(3)-Ca and HCO_(3)·SO_(4)-Ca types.Moreover,the NO_(3)type water appeared at the same time.Wherein,there are up to 14 kinds of hydrochemical types for construction land,followed by 13 kinds for cultivated land and 6 kinds for forest land.(3)The major ions in the groundwater were from the weathering and dissolution of carbonate and silicate rocks.The rock salt and gypsum were in an unsaturated state,and the calcite and dolomite were in dissolution and precipitation equilibrium.The results showed that the hydrochemical characteristics of shallow groundwater in the middle and lower reaches of the Dawen River Basin were mainly dominated by water-rock interaction and were also affected by human activities such as agricultural and industrial activities.