博斯腾湖以北绿洲区地下水化学特征时空变化规律及形成机制OA

Revealing the spatiotemporal evolution characteristics and driving mechanisms of groundwater chemis-try in the oasis region north of Bosten Lake can support the precise implementation of groundwater protection in this area.Using groundwater sample data from two periods(2016 and 2025)combined with groundwater flow field characteristics,this study employed mathematical statistics,hydrochemical diagrams,hydrogen and oxygen stable isotope methods,and the UNMIX model for systematic analysis.The results show that groundwater in the study area is generally neutral to weakly alkaline;the mean total dissolved solids(TDS)of phreatic water de-creased,while confined water remained slightly saline.The evolution of hydrochemical components was con-trolled by the groundwater burial depth gradient from the northwest recharge area to the southeast discharge area.As the runoff path extended and the water table became shallower,intense evaporation-concentration processes drove the accumulation of high TDS and major ion concentrations toward the southeastern lakeside zone.The an-ion composition became dominated by SO2-4,the medium-to-high-value area of NO-3 concentration continued to expand,and the HCO-3 concentration underwent a fundamental change.The chemical type of phreatic water re-mained stable,while the confined water tended toward the SO4·Cl-Ca·Mg type.Comprehensive analyses based on Gibbs diagrams,end-member plots,and ionic ratios indicate that groundwater hydrochemical evolution is jointly controlled by rock weathering and evaporation-crystallization,with rock weathering being dominant.Car-bonate influence has weakened,whereas silicate and evaporite dissolution has intensified,and cation exchange is predominantly positive.Agricultural input is an important anthropogenic source of elevated NO-3,while Cl-en-richment is mainly controlled by evaporation-concentration and evaporite dissolution,with additional influence from agricultural activities.The UNMIX model identified three major factors:an agricultural input-nitrification factor,an industrial input-silicate weathering composite factor,and a dissolution-evaporation-concentration salini-zation factor,contributing 22.22%,41.64%,and 36.14%,respectively.