Hydrochemical characteristics and their controls in Jining National High-tech Zone: A land-use perspective

Groundwater chemistry reflects both natural and anthropogenic processes. In rapidly urbanizing areas where agricultural and construction land coexist, differences in shallow groundwater chemistry remain poorly understood. This study compared hydrochemical characteristics between agricultural and construction land-use types in the Jining National High-tech Zone, China, using geochemical diagrams, ion ratios, mineral saturation indices, and multivariate statistics. Groundwater in the study area was generally neutral to weakly alkaline, with pH 6.78-7.51 in agricultural samples and 7.19-7.47 in construction samples. Agricultural groundwater had higher mean TDS (797.28 vs 624.00 mg/L in construction groundwater) but lower variation, suggesting spatially uniform carbonate dissolution. Conversely, construction groundwater displayed higher mean Na+ concentrations (59.85 mg/L) and greater hydrochemical heterogeneity. After Holm correction, pH, TDS, total hardness, and Ca2+ differed significantly between the two land-use types (adjusted p < 0.05), whereas the remaining parameters, including NO3-N, did not. The Cl- coefficient of variation exceeded 100% in construction areas, and NO3-N variability was elevated in agricultural areas. These patterns indicate mixed influences from silicate weathering, cation exchange, and localized anthropogenic inputs. Principal component analysis yielded three components: PC1 (44.62%) represented a mineralization gradient, PC2 (17.08%) reflected pH-alkalinity balance, and PC3 (14.17%) indicated silicate weathering versus carbonate dissolution. PC1 and PC2 scores differed significantly among land-use types (p = 0.007 and 0.009, respectively), but PC3 scores did not (p = 0.826). Overall, agricultural groundwater showed carbonate-dissolution dominance with pronounced nitrate enrichment (NO3-N 102.7%), while construction groundwater showed silicate-influenced, Na-Cl-coupled signatures with greater heterogeneity (Cl- 106.6%). These results link land-use differences to distinct shallow groundwater hydrochemical patterns, though such patterns may reflect combined influences of land use, hydrogeological setting, and aquifer lithology. The findings underscore the need for land-use-specific groundwater management in rapidly urbanizing agricultural-industrial regions and provide a baseline for future process-oriented research.