Abstract:

In order to study the atmospheric carbon sink effects of human activities such as land use of Karst catchments, the land use data of the two adjacent typical Karst basins were carried out by using a combination method of field surveys and remote sensing image analyses. The flux of atmospheric carbon sequestration and its intensity were calculated by the runoff coefficient method with the in situ data on physico-chemical parameters of the spring water of Chenqi and Dengzhanhe in Puding County, Guizhou. According to the comparative analysis of watershed land use types and Karst carbon sequestered intensity differences, we have gotten the following ideas: 1) The two spring watersheds had striking spatial variability of the land-use types with relatively consistent land use scale ratio, in which the land of the forest and bushwood were found in upper mountains, bared rock and grass on hill slope, dry land and paddy fields in highland or at foot of the hills, the paddy fields were distributed in highland of the upper discharging area of the Dengzhanhe spring watershed and at the hill foot of the lower discharging area of the Chenqi spring watershed, respectively. 2) the carbon sequestered intensity of the Chenqi and Dengzhanhe spring catchments were 1.24×10⁶ mol/（km²•a）and 1.44×10⁶ mol/（km²•a）respectively with significant seasonal variation，the rate of the atmospheric carbon sequestration in the larger area (Dengzhanhe spring catchment) was lower than that in the smaller area (Chenqi spring catchment); 3) Watershed land use types and their configuration relation, especially the paddy field configuration differences between the upper and lower reaches, resulted in the differences of carbon sequestration flux between the two adjacent small Karst spring watersheds (Chenqi Karst spring and Dengzhanhe Karst spring). The weathering process and its Karst dissolving intensity had important impact on the atmospheric carbon sequestration during the Karst processes. Human activity would be one of the effective ways to regulate the role of atmospheric carbon sinks during the rock weathering process of the basin.

Key words: land-use, rock weathering, atmospheric carbon sequestration, Karst basin