Seasonal changes of soil dissolution rate and estimations on carbon sequestration in the subalpine epikarst spring zone：A case study in the Shuifang Spring in Jinfoshan, Chongqing

Annual soil dissolution rates of carbonate under forestland, grassland and shrub land at different depth in the Shuifang Spring in Jinfoshan, Chongqing are tested by means of the standard limestone tablets. The results show that the karst erosion rates are quite different under different land-use types, in different seasons and at different depth of soil. Through analysis on soil organic matter, soil CO2 concentration and soil pH during different seasons and at different depth in forestland, grassland and shrub land, it is discovered firstly that the soil organic matter and pH coupled with each other to affect the dissolution rate of carbonate, and the higher the organism and the less the pH value, the higher the dissolution rate. And secondly, the soil CO2 concentration is of certain relations with the dissolution rate of carbonate, and the soil CO2 concentration in summer and autumn is higher than in winter and spring, so, the soil erosion rate in summer and autumn is higher than in winter and spring. Finally, an estimation on the carbon sequestration in the spring area is done by means of standard limestone tablets, the result is about 25.595 t/a.