Challenges

Global climate change concerns the future of all humanity, and cooperation and governance are essential to this issue. The Earth\’s critical zones control the material cycle and energy flow of the Earth\’s surface rock-soil-atmosphere-water-biological zones. Comparative observation and research on positioning are beneficial for enhancing the understanding of material migration, transformation, and service functions in the Earth\’s critical zones, and providing technical support for local ecological protection and sustainable economic and social development. Conducting comparative research and application demonstrations on carbon cycling processes in typical karst critical zones between China and Cambodia can quantitatively and accurately evaluate the carbon sink and potential for carbon sequestration in these zones. This is a practical implementation of the joint statement between China and Cambodia on building a community with a shared future in the new era.

Toward a Solution

According to statistics, the modern global karst distribution area is 22 million km², accounting for 15% of the land area. Among them, China\’s karst area reaches 3.44 million km², accounting for about 15.6% of the total global karst area. The southeastern part of Cambodia is located on the edge of the Indochina Plateau and has deposited a thick layer of carbonate salts, which is a typical representative of tropical karst. Under the interaction of water-carbon dioxide-carbonate rocks-organisms, karst carbon cycling is active, forming a karst carbon sink of 0.84 Pg C/a globally, accounting for about 30% of the global \”missing sink\”. However, due to the lack of precise and systematic assessment of karst carbon sinks, there is still controversy over the mechanism of their generation. This is because the carbon sequestration rate, as an important parameter for carbon sink assessment, currently has significant differences in its calculation and a considerable degree of uncertainty. The critical zones of the Earth control the material cycle and energy flow of the rock soil atmosphere water biological zones on the Earth\’s surface. Comparative observation and research on positioning are beneficial for enhancing the understanding of material migration, transformation, and service functions in the critical zones of the Earth, and providing technical support for local ecological protection and sustainable economic and social development.

According to karst dynamics theory, this project conducts a comparative study on carbon cycle monitoring of five types of karst critical zones (Tropical karst critical zone, subtropical karst critical zone, temperate karst critical zone, cold karst critical zone, arid karst critical zone) under different climatic backgrounds in China and Cambodia. High resolution and multi-element dynamic monitoring of subsystems such as atmosphere, vegetation, soil, soil water, groundwater, and spring water is carried out to reveal the key driving factors and dynamic mechanisms of carbon cycle in typical karst critical zones. A karst carbon cycle model of water rock soil gas interaction in typical karst critical zones is constructed, and the potential assessment of karst carbon sink in China and Cambodia is carried out, providing strong support for establishing a karst carbon cycle research framework based on critical zone theory.

Moreover, conducting comparative research and application demonstrations on carbon cycling processes in typical karst critical zones between China and Cambodia can quantitatively and accurately evaluate the carbon sink and potential for carbon sequestration in karst critical zones. This not only fully implements the Joint Statement on Building a Community with a Shared Future for China and Cambodia in the New Era, but also fully recognizes that conducting carbon cycling research in karst critical zones as a \”nature based solution\” is an important means to achieve the \”dual carbon\” goal and provide technical support for promoting economic and social development.

Then, with the joint assistance from China, the Cambodian National Geological Laboratory has been established. The laboratory covers an area of 14000 square meters, making it Cambodia\’s first national geological laboratory. The laboratory is known as a landmark project in the field of China and Cambodia mineral resources exploration and development cooperation, and is also one of the important achievements of China in helping the country jointly build the \”the Belt and Road\” initiative. Moreover, the China-Cambodia Karst critical Zone Science and Technology Joint Research Center and the Cambodia Karst critical Zone Observation Station were established. Through this project, we will continue to provide follow-up instrument installation and personnel training for the Cambodian National Geological Laboratory and carry out the construction of field monitoring stations in critical karst zones in Cambodia.