Li Weimo, Wang Binbin, Ma Yaoming
College of Atmospheric Science, Lanzhou University, Lanzhou 730000, China; Land-Atmosphere Interaction and its Climatic Effects Group, State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China.
Land-Atmosphere Interaction and its Climatic Effects Group, State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; National Observation and Research Station for Qomolongma Special Atmospheric Processes and Environmental Changes, Dingri 858200, China; Kathmandu Center of Research and Education, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2024 Aug 15;938:173408. doi: 10.1016/j.scitotenv.2024.173408. Epub 2024 May 24.
This study quantitatively evaluates the carbon dioxide (CO) sink intensity of a large saline lake (area > 2000 km) and a small saline lake (area 1.4 km) on the Tibetan Plateau (TP), alongside an alpine meadow, by analysing their net ecosystem exchange (NEE) figures obtained by eddy covariance (EC) measurements. Specifically, the "large lake" exhibits an NEE value of -122.51 g C m yr, whereas the small lake has an NEE value of -47.17 g C m yr. The alpine meadow, in contrast, demonstrates an NEE value of -128.18 g C m yr. Through standardization of the eddy flux data processing and accounting for site-specific conditions with a wind direction filter and footprint analysis, the study provides robust estimates of CO sink intensity. The "large lake" was found to absorb CO primarily during non-icing cold periods with minimal exchange occurring during ice-covered season, whereas the "small lake" showed no significant CO exchange throughout the year. On the other hand, alpine meadows engaged in CO uptake during the vegetative growth season but showed weak CO release in winter. CO uptake in lakes is mainly controlled by ice barrier and chemical processes, while biological processes dominate the alpine meadow. The carbon sink intensity of the TP's saline lakes is estimated to be 1.87-3.01 Tg C yr, smaller than the previous reported estimations. By evaluating the CO sink intensity of different lakes, the study highlights the importance of saline lakes in regional carbon balance assessments. It specifically points out the differential roles lakes of various sizes play in the carbon cycle, thereby enriching our understanding of carbon dynamics in high-altitude lacustrine ecosystems.
本研究通过分析涡度相关（EC）测量获得的净生态系统交换（NEE）数据，对青藏高原（TP）上一个大型盐湖（面积>2000平方千米）、一个小型盐湖（面积1.4平方千米）以及一片高寒草甸的二氧化碳（CO₂）汇强度进行了定量评估。具体而言，“大型湖泊”的NEE值为-122.51克碳/平方米·年，而小型湖泊的NEE值为-47.17克碳/平方米·年。相比之下，高寒草甸的NEE值为-128.18克碳/平方米·年。通过对涡度通量数据处理进行标准化，并利用风向过滤器和足迹分析考虑特定地点条件，该研究提供了可靠的CO₂汇强度估计值。研究发现，“大型湖泊”主要在非结冰寒冷期吸收CO₂，在冰封季节交换极少，而“小型湖泊”全年CO₂交换不显著。另一方面，高寒草甸在营养生长季节吸收CO₂，但冬季CO₂释放较弱。湖泊中的CO₂吸收主要受冰障和化学过程控制，而高寒草甸中生物过程占主导。青藏高原盐湖的碳汇强度估计为1.87-3.01太克碳/年，比先前报道的估计值小。通过评估不同湖泊的CO₂汇强度，该研究突出了盐湖在区域碳平衡评估中的重要性。它特别指出了不同大小湖泊在碳循环中所起的不同作用，从而丰富了我们对高海拔湖泊生态系统碳动态的理解。
