大汶河流域中上游地区岩溶地下水水化学特征及其控制因素分析

为查明大汶河流域中上游地区岩溶地下水水化学特征和离子来源, 基于2018年枯、丰两期采集的岩溶地下水样品水化学数据, 综合运用数理统计、相关性分析、Piper图、Gibbs图以及离子比值等方法, 对大汶河流域中上游地区岩溶地下水水化学特征及其控制因素进行了分析。结果表明，大汶河流域中上游地区枯、丰水期岩溶地下水的pH均值分别为7.6和7.5, 整体表现为弱碱性。岩溶地下水中Ca2+为占优势的阳离子, HCO₃-和SO₄2-为主要阴离子。枯、丰期岩溶地下水中ρ(TDS)均值分别为645.4, 648.4 mg/L。按照TDS划分, 大汶河流域中上游地区岩溶地下水均属于淡水或微咸水；枯、丰水期岩溶地下水水化学类型均以HCO₃·SO₄-Ca为主。岩石风化作用是控制区内岩溶地下水水化学特征的主要控制因素, 碳酸盐岩和硅酸盐岩矿物的溶解是地下水主要离子的重要来源。同时, 大汶河流域中上游地区岩溶地下水还受到了比较明显的人为输入影响, 地下水中NO₃-主要来自于农业生产活动。该研究成果为水资源利用提供了指导作用。 

Hydrochemical characteristics and controlling factors of karst groundwater in middle and upper reaches of Dawen River basin

To determine the hydrochemical characteristics and ion sources of karst groundwater in the middle and upper reaches of the Dawen River basin, based on karst groundwater samples collected in dry and wet periods in 2018, hydrochemical data were analyzed by means of mathematical statistics, correlation analysis, Piper diagram, Gibbs diagram and ion ratios. The results showed that the average pH values of karst groundwater in dry and wet periods in the middle and upper reaches of the Dawen River basin were 7.6 and 7.5, respectively, showing weak alkaline conditions as a whole. Ca2+ was the dominant cation in karst groundwater, and HCO₃- and SO₄2- were the main anions. The average contents of TDS in karst groundwater during the dry and wet periods were 645.4 mg/L and 648.4 mg/L, respectively. According to TDS, the karst groundwater in the upper and middle reaches of the Dawen River basin belonged to freshwater or brackish water; hydrochemical types of karst groundwater in dry and wet periods were mainly HCO₃·SO4-Ca. Rock weathering was the main controlling factor affecting the hydrochemical characteristics of karst groundwater in the area. The dissolution of carbonate and silicate minerals was an important source of groundwater ions. At the same time, the karst groundwater in the upper and middle reaches of the Dawen River basin was also affected obviously by human activities, and NO₃- in groundwater mainly came from agricultural production activities.