Advance of Karst Critical Zone and Its Carbon Cycle

The category of karst critical zone includes surface karst zones with strong carbon-water-calcium cycle composed of atmosphere-precipitation-vegetation-soil-fissure-bedrock-water and huge karst underground space composed of karst pipeline/fissure-cave-underground river-aquifer, which is the frontier direction of karst earth system science research. This paper summarized the research results of carbon cycle and its effect on atmospheric CO₂ source and sink from the scientific development of karst earth system up to now, including the early carbon migration model,the calculation methods and results of current mainstream regional carbon sink and the new discovery of bio-carbon pump, etc. It discussed the problems that the current research frameworks of karst carbon cycle are too single or inconsistent and time scales of carbon turnover are not the same. It was proposed that systematic monitoring of carbon input, storage and output in karst critical zone should be carried out. The importance of karst carbon sinks in the global carbon cycle model should be more convincing through the construction of online high-resolution monitoring sites and the "3S" technology to achieve point-to-area research.