莱州湾东岸地下水化学及盐化特征

摘要

The research on hydrochemical characteristics and salinization mechanism of groundwater plays an important role in understanding the environmental evaluation of groundwater and the reasonably planning,utilization and management of groundwater resources. The study is intended to research the hydrochemical characteristics and salinization mechanism of the groundwater in the northeast coast of the Laizhou Bay by descriptive statistics, correlation analysis, Piper diagram, saturation index and ion ratios and so on. The results show that major cations and anions such as Cl-、 HCO 3- and Ca2+have higher concentrations while Mg2+and K+have lower concentrations in the study area. The pollution of nitrate in the study area is severe. The average concentration of NO3- is 172.88 mg/L, higher than the fifth level of the water quality. In view of variation coefficients, the values of Cl-、 SO42-、 Na+and K+are much higher than those of the others, showing that the formers play a more significant role in the salinization of the groundwater and are vulnerable to the environment. Groundwater facies are very complex in this area, and can be classified into Ca, Ca·Mg (Ca·Mg·Na) , Ca·Na (Ca·Na·Mg) and Na Ca types in terms of cations while Cl, Cl·HCO3 (HCO3·Cl), HCO3·Cl·SO4 (Cl·HCO3·SO4), Cl·SO4, Cl·SO4·HCO3 and HCO3·SO4·Cl (SO4 HCO3·Cl)types in terms of anions. The mass concentration of TDS presents the significant characteristics of spatial structures, showing that TDS concentration is increasing from the center to border areas and decreasing from coastal areas to the inland. Ion ratios and saturation index plots indicate that main hydrochemical processes are inferred to control the groundwater chemical composition:evaporation concentrating, mineral dissolution, cation exchange and human activities. The main origins of conventional ions are halite, dolomite, calcite and gypsum.%以莱州湾东岸为研究区，利用统计分析、相关性分析、Piper图、饱和指数以及离子比例等方法系统研究了该区的浅层地下水化学特征及盐化机理。结果表明，水化学参数Cl-、HCO3-和Ca2+离子浓度较高，而Mg2+、K+离子浓度很低，研究区硝酸盐污染严重，平均离子浓度高达172.88 mg/L，为劣五类水质；Cl-、SO42-、Na+和K+的离子浓度变异系数较大，是随环境变化的敏感因子，是决定地下水盐化的主要变量；该区地下水中Ca2+、Mg2+和Cl-占主要优势，地下水化学类型复杂，按阳离子主要划分为Ca、Ca·Mg （Ca·Mg·Na）、Ca·Na （Ca·Na·Mg）及Na·Ca型水；按阴离子主要有Cl、Cl·HCO3（HCO3·Cl）、HCO·Cl·SO4（Cl·HCO3·SO4）、Cl·SO4、Cl·SO4·HCO3以及HCO3·SO4·Cl （SO4·HCO3·Cl）型水；TDS质量浓度呈现显著的空间结构性特征，表现为从中部向两侧浓度逐渐升高，由海向陆TDS质量浓度逐渐降低，南部TDS质量浓度要显著大于北部；蒸发沉积、溶滤、阳离子交换作用以及人类活动的影响是浅层地下水盐化的主要控制因素；岩盐、白云石、方解石以及石膏等矿物是地下水常规离子的主要物源。