High-resolution study on the hydrochemical variations caused by the dilution of precipitation in the epikarst spring: an example spring of Landiantang at Nongla,Mashan, China |
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Authors: | Qiang Li Hailong Sun Jun Han Zaihua Liu Longjiang Yu |
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Institution: | (1) School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China;(2) Karst Dynamics Laboratory, MLR, Institute of Karst Geology, CAGS, 50 Qixing Road, Guilin, Guangxi, 541004, China;(3) The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang, 55002, China |
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Abstract: | In addition to rainfall, high-resolution measurements of water level, pH, specific conductivity and temperature of Landiantang
epikarst spring at Nongla, Mashan county in Guangxi Province, China were recorded in summer rainy season by using a data logger
with time interval of fifteen minutes. Water from the spring issues along a karst conduit. During the rainstorms in summer,
it was found that the pH and temperature of Landiantang spring increased while its specific conductivity decreased. As HCO3
−, Ca2+ and Mg2+ are the dominant ions, linear relationships between concentrations of those ions and specific conductivity were developed.
According to the ion concentrations from the linear relationships, the saturation indexes of calcite (SIC), the saturation indexes of dolomite (SID) and CO2 partial pressure (Log
) of the spring were calculated. Results indicated that the Log of the spring during the rainstorms was lower than that without rain, and its SIC and SID was also lower. Combined with the characteristics of the epikarst zone, it was inferred that the above results were caused
by the dilution of rainwater, because overland flow with high pH (due to neutralization of carbonate rock dusts in the air
to rainwater) and low specific conductivity traveling through the conduit rapidly during rainstorms, showed greater influences
on the hydrochemical variations of the epikarst spring. |
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Keywords: | Epikarst zone Auto data logging Hydrochemical variation The dilution of precipitation Landiantang spring China |
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