Analysis of Hydrochemical Characteristics and Pollution Sources Based on Multi-Model Approach: A Case Study of the Wuhan Karst Region

Karst terrains hold vital global groundwater reserves, underpinning regional water security and ecological stability. To elucidate groundwater hydrochemical patterns and formation mechanisms in Wuhan’s karst zone, this study adopted the Gibbs model, correlation analysis, principal component analysis and positive matrix factorization to explore water–rock interactions, hydrochemical origins, element migration, hydrogeochemical facies and genetic processes. The results show that water in both confined porous loose rock aquifers (CPLRAs) and karst fissure carbonate rock aquifers (KFCRAs) is mainly of HCO₃–Ca and HCO₃·SO₄–Ca types. Carbonate dissolution dominates hydrochemical evolution, with Ca²⁺, Mg²⁺, and HCO₃⁻ as major ions. Natural water–rock interactions control the ionic characteristics of both groundwater types. Silicate weathering exerts a greater influence on water in the KFCRA, while water in the CPLRA has more complex ion sources. Anthropogenic activities contribute 17.52% and 17.61% to their hydrochemical variations, suggesting moderate human influence. Water in the CPLRA is mainly affected by domestic sewage and soil organic nitrogen, locally superimposed with industrial and mining disturbances. Water in the KFCRA is primarily influenced by agricultural pollution, with minor domestic sewage input. These findings provide a scientific basis for sustainable development, protection, and targeted pollution control of groundwater resources in the Wuhan karst area, and offer a reference for hydrochemical studies in comparable karst regions.