Study on the hydrochemical characteristics and formation mechanism of shallow groundwater in Karst Area,Meijiao Town,Ganzhou
Unravelling the recharge sources and water rock interaction processes of groundwater in karst area is of great significance for rational utilization of water resources and protection of karst water resources and water ecology.This paper used mathematical statistics,Gibbs diagram,and forward succession and end-member mixing models to qualitatively and quantitatively investigate the hydrochemical characteristics and evolution process of shallow groundwater in Karst Area,Meijiao Town,Ganzhou.The results showed that the shallow groundwater was weakly alkaline.The TDS value ranged between 27.61 mg·L-1 and 360.75 mg·L-1 with an average of 179.13 mg·L-1,and the hydrochemical type was mainly HCO3-Ca.Groundwater hydrogen and oxygen stable isotopes were distributed along the local meteoric water line,indicating that precipitation was the main source of recharge into the aquifers,with unsignificant impact of evaporation.Groundwater chemical compositions were mainly controlled by rock weathering and human activities.Ca2+,Mg2+and HCO3 mainly originated from the dissolutions of carbonatite,silicate and evaporates.Na+and K+was mainly derived from the dissolutions of silicate.Distribution of Cl-,SO42-and NO3 was attributed to the effect of human activities.Results of forward succession-end-member mixing modeling indicated that the average contribution of rock weathering to groundwater constituents was 78.74％,and this of atmospheric input and human activities was 12.50％and 8.76％,respectively.In rock weathering,carbonate rock contributed the most(67.64％)to groundwater composition,followed by silicate rock(7.33％)and evaporites(3.77％).Carbonate weathering is dominated by limestone which had an average contribution rate of 60.33％to groundwater composition,followed by dolomite,with an average contribution rate of 29.76％.
Karst Areashallow groundwaterhydrochemistryhydrogen and oxygen isotopesformation mechanism
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