The Application of Stable Carbon Isotope to the Study of Carbon Sources in Guijiang Watershed, Guangxi
利用稳定同位素技术研究广西桂江流域水体中碳的来源

This paper analyzed the stable isotope of organic carbon in Guijiang watershed of Guangxi and studied the water pre-treatment separation and purification techniques for organic carbon isotope in different samples collected in the karst area. The results show that C3 plants have a remarkable contribution to the content of organic carbon in water of the Guijiang River, whereas aquatic organisms have a small impact. The Fuhe River has higher content of dissolved organic carbon (DOC) than that of the Lijiang River because there is high intensity of microbial activity in soil and DOC has more production in non-karst areas. Karstification has major contribution to water dissolved inorganic carbon (DIC), while DIC and stable carbon isotope values in karst areas show complex variation, which may be related to different carbon isotopes of CO2 from plant root respiration, microbial activity or organic matter mineralization, and also to CaCO3 saturated and CO2 released from the main river. Different forms of carbon isotope values reflect the changes of carbon in the river between the karst areas and the non-karst areas, which provides a foundation for the study of the source of carbon.