ABSTRACT
Totally 49 water samples were collected in Shibing Dolomite Karst World Natural Heritage Site in Guizhou Province to analyze the characteristics and controlling factors of both the surface and underground waters, as well as the features and their origins of the dissolved inorganic carbon isotope. It was found that the pH of the study area was neutral to alkaline with low concentrations of total dissolved solids. The cations were dominated by Ca2+, Mg2 and anions by HCO3-, featured by HCO3-Ca x Mg type water. The ratios of Cl-, NO3- and SO4(2-) in the allogenic water from the shale area in the northern catchment were higher than those in autogenic water from the dolomite karst area, so did the concentration of Si. The SIc and SId of the allogenic waters in the shale area were negative. After the waters entered into and flew by the dolomite karst area, both the SIc and SId increased to over 0. It could be told by the water chemistry that the hydrochemistry was little impacted by the rainfall and human activities. The Gibbs plot revealed that the chemical composition of the waters was mainly controlled by rock weathering. The δ(13)C(DIC) of the surface waters ranged from -8.27% to -11.55% per hundred, averaging -9.45% per hundredo, while that of the underground waters ranged from -10.57% per hundred to -15.59% per hundred, averaging -12.04% per hundred, which was lighter than that of surface water. For the distribution features, it was found the δ(13)C(DIC), of the upper reaches of branches of Shangmuhe River was lighter than that of the lower reach, while that of the main river Shangmuhe River was relatively complex. Based on the mass balance of stable isotopes and the δ(13)C(DIC), the ratio of the origin of DIC of the ground water was calculated. It was found that 51.2% was from soil CO2, and 48.8% was from the rock itself.
