利用稳定同位素技术研究广西桂江流域水体中碳的来源

摘要

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.%本文对岩溶区不同类型样品中的有机碳同位素样品前处理的分离提纯技术进行了研究,并对广西桂江流域水体进行了稳定有机碳同位素分析.结果表明,C3植物对桂江水体可溶性有机碳(DOC)有很大比例的贡献,而水生生物对水体有机碳影响较小.抚河流域比漓江流域有较高的(DOC)含量,可能与非岩溶区土壤微生物活动强,土壤活性有机碳含量高有关.岩溶作用对水体可溶性无机碳(DIC)的贡献较大,岩溶区DIC浓度和稳定碳同位素值变化较大且复杂,可能与流域内土壤中植物根系呼吸、微生物活动或有机质矿化等作用产生的土壤CO2碳同位素值不同有关,也可能与水体中CaCO3过饱和生成碳酸钙沉淀向大气释放CO2有关.不同形态的碳同位素值反映了岩溶区和非岩溶区河流中碳的变化,为研究碳的来源提供了一定的依据.