Preliminary study on short-time carbon absorption in epikarst spring basin─A case of the Shuifang Spring in Jinfo Mountain, Chongqing

The study mainly focus on the Shuifang epikarst spring basin. By using the multi-parameter instrument CDTP300, interannual continuous data of conductivity, water temperature and water level are got. Annual and monthly CO2 consumption in two years are calculated by means of karst hydrochemistry-discharge method. The result shows that CO2 consumption of Shuifang Spring is relatively high in June, July and August; while it’s low in January, February and December. The maximum value of CO2 absorptive quantity appeared in July and the minimum in January. The result also shows that the monthly discharge of the Shuifang Spring and rainfall are intensively correlated with the CO2 consumption, and the CO2 consumption in rainy season is much larger than dry season. The bicarbonate concentration of the Shuifang Spring is influenced by air temperature, rainfall, discharge and soil CO2. There are two months time-delay between the biggest monthly CO2 consumption and the highest bicarbonate concentration. Through this study it is found that the estimate of carbon flux in small watersheds by hydrochemistry-discharge method is more accurate than large watersheds and it may give an effective method to the further research on carbon sink for karstification and its control mechanism in epikarst zone.