Effects of snowfall and tourism activities on water chemistry of surface karst springs in the Jinfo Mountain

The Jinfo Mountain is a world natural heritage which attracts many tourists to visit its scenic spots in winter. The purpose of this work is to explore the effects of snowfall and tourism activities on the surface karst springs in this area. We conducted high-frequency automatic sampling monitoring of chemical changes in water springs during a large-scale snowfall in December 2014, obtaining high resolution hydrochemical change curves, which were compared with physical and chemical characteristics of atmospheric precipitation, soil water and sewage. Principal component analysis (PCA) was used to determine the main factors affecting spring water chemistry. The physical and chemical indexes of spring water show significant dynamic changes in different stages of snowfall, at the beginning of snow cover period(2014-12-10 to 2014-12-14), most of the hydrochemical indicators were stable largely; afterwards until the large area of snow melted (2014-12-15 to 2014-12-28), the amount of tourism emissions increased, spring water temperature, flow rate, turbidity, salinity and ion content exhibited an upward trend, while pH, dissolved oxygen showed a downward trend, and hydrochemical indicators changed greatly. During the melting of the snow, the melt water supply increased the dissolved oxygen and turbidity of the spring water, and other water chemical indicators first decreased and then rose. Principal component analysis shows that the sewage input of tourism activities was the primary factor causing the change of spring water quality, and the contribution rate of principal components reached 59%. The dilution effect of snow melting can relieve the groundwater pollution situation in the basin to a certain extent, which is the second influencing factor, with a contribution rate 31%.