青海省北川河流域孔隙水水化学特征及源贡献解析

根据2020年采集的53个青海省北川河孔隙水样品，利用ArcGIS10. 7、SPSS20. 0、Origin2022等软件，基于APCS-MLR模型研究了北川河流域孔隙水水化学特征及并定量分析来源贡献率，结果表明：（1）研究区孔隙水pH介于7. 0～8. 0，呈中性～弱碱性。沿水流方向，Ca2+和HCO-3质量浓度逐渐降低，Na+、Cl-和SO2-4质量浓度逐渐升高，水化学类型逐渐由HCO-3-Ca2+和HCO-3·SO2-4-Ca2+转化为HCO-3·SO2-4-·Cl--Na+·Ca2+和HCO-3·SO2-4·Cl--Na+型，与上游相比，TDS及Na+、Ca2+、Cl-、SO2-4等主要离子质量浓度均明显增高，下游水质变差。（2）北川河流域孔隙水水化学特征总体受矿物溶滤作用的控制，硅酸盐岩、碳酸盐岩矿物溶解是地下水化学组分的主要来源，同时阳离子交换作用强烈，上游到下游，蒸发浓缩作用显著增加，人类活动增加，对孔隙水水化学特征有一定影响。（3）北川河流域上游孔隙水主要受天然状态下的水文地球化学进程控制，APCS-MLR模型表明，碳酸盐岩矿物溶滤，岩盐钾盐溶解和离子交换，蒸发浓缩的贡献率分别为35. 93%，29. 68%，26. 54%。下游孔隙水中硅酸盐岩溶解、蒸发浓缩作用、工业活动，农业活动，碳酸盐岩矿物溶解的贡献率分别为41. 27%、27. 73%、22. 91%，应加强下游流域水源保护工作。

Hydrochemical characteristics and source contribution analysis of pore water in Beichuan River Basin，Qinghai Province

According to the 53 pore water samples of Beichuan River in Qinghai Province collected in 2020, the hydrochemical characteristics of the pore water in the Beichuan River Basin and the quantitative analysis of the contribution of the sources were investigated.Methods:Using ArcGIS10.7, SPSS20.0 and Origin2022 software, the hydrochemical characteristics of the pore water in the Beichuan River Basin and the quantitative analysis of the source contribution were studied based on the APCS-MLR model. Results:The results showed that:(1)The pH of the pore water in the study area ranged from 7.0 to 8.0 and was neutral to weakly alkaline. Along the direction of water flow, the mass concentrations of Ca2+ and HCO-3 gradually decreased, and the mass concentrations of Na+, Cl- and SO42- gradually increased, and the hydrochemical type was gradually transformed from HCO-3-Ca2+ and HCO-3·SO2-4-Ca2+ to HCO-3·SO2-4-·Cl--Na+·Ca2+and HCO-3·SO2-4·Cl--Na+ type, compared with the upstream, the mass concentration of TDS and major ions such as Na+, Ca2+, Cl-, SO2-4 increased significantly, and the downstream water quality became worse.(2)The hydrochemical characteristics of pore water in Beichuan River Basin were generally controlled by mineral dissolution and filtration, silicate rock, carbonate rock mineral dissolution were the main source of chemical components of groundwater, while cation exchange was strong, upstream to downstream, evaporation and concentration increased significantly, and the increase in human activities, which had a certain impact on the pore water hydrochemical characteristics.(3)The pore water in the upstream of Beichuan River Basin was mainly controlled by hydrogeochemical processes in the natural state, and the APCS-MLR model showed that the contributions of carbonate rock mineral leaching, rock salt potassium salt dissolution and ion exchange, and evapotranspiration and concentration were 35.93%, 29.68%, and 26.54%, respectively. The contribution of silicate rock dissolution, evaporation concentration, industrial activities, agricultural activities, and carbonate rock mineral dissolution in the downstream pore water were 41.27%, 27.73%, and 22.91%, respectively.Conclusions:The activity of industry and agriculture in the downstream pore water was greater than that in the upstream.We should strengthen the protection of water resources in the downstream basin.