Distribution and assessment of hydrogeochemical processes of F-rich groundwater using PCA model: a case study in the Yuncheng Basin, China

摘要

Hydrogeochemistry and factor analysis were conducted together to assess the distribution and the major geochemical processes in fluoride-contaminated shallow groundwater in the Yuncheng Basin.Spatially,fluoride concentration was low(<1.5 mg/L)in the southern piedmont plain,medium(<4 mg/L)in the central basin,and high(up to 14.1 mg/L)in Kaolao lowland areas in shallow aquifers.A three-factor principal component analysis model explained over 75.1%of the total variance.Sediment weathering leaching and evapotranspiration were recognized as the first primary hydrochemical processes response for the groundwater chemistry and explained the largest portion(42.1%)of the total variance.Factor two reflects the negative influence of human activities,with a positive loading of NO3^-and HCO3^-,and negative loading of well depth.Fluoride-bearing mineral dissolution and alkaline condition was ranked as the third factors responding for groundwater chemistry and explained 11.2%of the total variance.