Dissolved organic carbon, CO2, and CH4 concentrations and their stable isotope ratios in thermokarst lakes on the Qinghai-Tibetan Plateau

• Published in: Journal of Limnology
• Main Authors: Cuicui Mu, Tingjun Zhang, Qingbai Wu, Xiaoqing Peng, Peng Zhang, Yuzhong Yang, Yandong Hou, Xiankang Zhang, Guodong Cheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: PAGEPress Publications 2016
• Subjects: Qinghai-Tibetan Plateau; thermokarst lakes; greenhouse gas; dissolved organic carbon; stable carbon isotope; envir; geo; permafrost; Thermokarst
• Online Access: https://doi.org/10.4081/jlimnol.2016.1346; https://doaj.org/article/2336485da446444097e5ee628048bd59

Thermokarst lakes are widely distributed on the Qinghai-Tibetan Plateau (QTP), which accounts for 8% of the global permafrost area. These lakes probably promote organic matter biodegradation and thus accelerate the emission of carbon-based greenhouse gases. However, little is known about greenhouse gas concentrations and their stable isotopes characteristics of these lakes. In this study, we measured the concentrations of dissolved organic carbon (DOC), dissolved CO2 and CH4, as well as the distribution of δ13CCO2, δ13CCH4, and δ13COM (organic matter) of lake sediments in thermokarst lakes on the QTP. Results showed that the OM of the lake sediments was highly decomposed. The concentrations of DOC, CO2 and CH4 in the lake water on the QTP were 1.2–49.6 mg L–1, 3.6–45.0 μmol L–1 and 0.28–3.0 μmol L–1, respectively. The highest CO2 and CH4 concentrations were recorded in July while the lowest values in September, which suggested that temperature had an effect on greenhouse gas production, although this pattern may also relate to thermal stratification of the water column. The results implied that thermokast lakes should be paid more attention to regarding carbon cycle and greenhouse gas emissions on the QTP.