LI Longbo^1,2, ZANG Xingyong³, CAI Dawei¹

(1.Guizhou Institute of Geo-Environment Monitoring, Guiyang 550081, China；
2.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China；
3.Key Laboratory of Karst Environment and Geohazard Prevention, Ministry of Land and Resources, Guizhou University, Guiyang 550025, China)

Abstract: Rocky desertification in the karst region of Southwest China with Guizhou Province as the center is one of the fundamental regional environmental problems faced by China in the implementation of the western development strategy. Rocky desertification in karst area is a land degradation process associated with fragile ecological background and human activities, and soil degradation is the core part of land degradation. In this study, soil samples from sandstone yellow soil profile and calcareous soil profile in Guizhou karst area were collected. The soil organic carbon content, soil carbonate content and its δ13C of the profile samples were measured. The results showed that the distribution of carbonate in sandstone yellow soil and calcareous soil was different. The overall change of carbonate content in black limestone soil decreased gradually from top to bottom. While, for yellow limestone soil, carbonate mainly concentrated in surface soil, and little change was found for sandstone yellow soil. In addition, the variation of δ13C in sandstone yellow soil and calcareous soil is different, which indicates the degree of transformation from organic carbon to inorganic carbon. The difference of soil forming process and degree, soil forming environment may be the main reason for the difference of δ13C composition between sandstone yellow soil and calcareous soil. This study improves the understanding of regional carbon pool characteristics and provides theoretical support for the study of biogeochemical cycle of soil organic matter in karst ecosystem.

Key word: Guizhou; karst area; soil carbonate; carbon isotope

EARTH AND ENVIRONMENT Vol.49, No.4, Tot No.342, 2021, Page 409-415