title: Hydrochemistry and coal mining activity induced karst water quality degradation in the Niangziguan karst water system, China.
abstract: Hydrogeochemical analysis, statistical analysis, and geochemical modeling were employed to evaluate the impacts of coal mining activities on karst water chemistry in Niangziguan spring catchment, one of the largest karst springs in Northern China. Significant water quality deterioration was observed along the flow path, evidenced from the increasing sulfate, nitrate, and TDS content in karst water. Karst water samples are Ca-Mg-HCO3 type in the recharge areas, Ca-Mg-HCO3-SO4 type in the coal mining areas, and Ca-Mg-SO4-HCO3/HCO3-SO4 type in the rural areas and discharge areas. A four-factor principal component analysis (PCA) model is conducted which explains over 82.9% of the total variation. Factor 1, which explained the largest portion (45.33%) of the total variance, reveals that coal mining activities and natural water-rock interaction as the primary factors controlling karst water quality. Anthropogenic effects were recognized as the secondary factor with high positive loadings for NO3 (-) and Cl(-) in the model. The other two factors are co-precipitation removal of trace elements and silicate mineral dissolution, which explained 20.96% of the total variance. A two-end mixing modeling was proposed to estimate the percentage of coal wastewater giving on karst water chemistry, based on the groundwater sulfate chemistry constrains rather than sulfur isotopes. Uncertainty of sulfur isotope sources led to an overestimation of coal mining water contribution. According to the results of the modeling, the contribution of coal mining waste on karst water chemistry was quantified to be from 27.05 to 1.11% which is ca. three times lower than the values suggested using a sulfur isotope method.
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 388, Lumo Road, 430074, Wuhan, Hubei, People's Republic of China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 388, Lumo Road, 430074, Wuhan, Hubei, People's Republic of China.
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, No. 388, Lumo Road, 430074, Wuhan, Hubei, People's Republic of China. xubo.gao.cug@gmail.com.|University of Texas at Austin, Austin, TX, 78705, USA. xubo.gao.cug@gmail.com.
authors.forename: Xubo
authors.initials: X
authors.lastname: Gao
mesh_terms: D002681:China; D003032:Coal Mining; D004784:Environmental Monitoring; D060587:Groundwater / Q000737:chemistry; D009566:Nitrates / Q000032:analysis; D014867:Water / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D060753:Water Quality
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D014867:Water
keywords: China; Coal mining activity; Degradation; Hydrochemistry; Karst water quality; Niangziguan karst spring catchment