Progress on karst carbon cycle and carbon sink effect study and perspective

Abstract

Carbonate weathering is an important part of the global carbon cycle, acts as an atmospheric and soil CO2 sink. Driven by ecosystem factors and affected by global change, carbon sinks in karst areas have the characteristics of surface and underground carbon sinks.This work briefly introduces the relationship between the karst carbon cycle and global change, discusses the related scientific issues and main progress of karst carbon sinks, analyzes the potential of karst sink increases and land use changes, and further proposes a conceptual model of carbonate weathering processes based on the concept of karst critical zones.Carbon sink generated by weathering of carbonate rocks may contribute to the "missing sink" of the global carbon cycle and play a role in mitigating the release of soil CO2 to the atmosphere, thus becoming an important regulator of the item of "land use change" (ELUC) in the global carbon cycle model.The carbonate weathering process responds quickly to short-time scale environmental factors, which is the core driving mechanism that connects biological, hydrological, as well as geochemical processes in karst critical zones.The karst carbon cycle can be regarded as an extension or lateral component of the soil-ecosystem carbon cycle, which together constitute a complete terrestrial shallow surface carbon cycle system in karst areas.The negative feedback effect of carbonate weathering on the increase of atmospheric CO2 concentration and the continuous promotion of rock desertification control and ecological restoration contain huge potential for karst carbon sequestration and sink increase.The monitoring and research on seasonal and regional variations in soil CO2 should be strengthened, and an inverse model based on the correlation between soil CO2 and the watershed hydrochemistry index should be constructed to estimate the background of the regional carbon sink and evaluate the annual carbon sink increment and potential, thus providing a clearer and effective scheme and approach for karst sink increase.

Keywords

• karst carbon cycle
• carbon sink effect
• source reduction
• reverse model
• sink increase potential
• carbonate weathering
• karst critizal zone