Wang Zhigang, Li Xiaoyan, Liu Xin, Ding Ruiqiang, Miao Chiyuan
State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; School of Natural Resources, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.
Sci Total Environ. 2024 Nov 15;951:175720. doi: 10.1016/j.scitotenv.2024.175720. Epub 2024 Aug 22.
How environmental factors affecting dissolved carbon remains unclear in lakes on the Qinghai-Tibetan Plateau (QTP), which limits the understanding of the lake carbon cycle. In this study, 60 lakes on the QTP in summer were investigated to clarify the variation in dissolved carbon, estimate dissolved carbon storage, and reveal how environmental factors affect the variation in dissolved carbon. The average dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) contents of 60 lakes on the QTP in summer were 12.78 mg/L and 103.66 mg/L, respectively. Salinity and total nitrogen were the important drivers of variations in DIC and DOC, respectively. Lake salinity and temperature were reduced only when precipitation was >50 mm, thus affecting the variations in lake dissolved carbon. Importantly, the elevation and area of the lake also significantly affected the variation in lake dissolved carbon. The total storage amounts of DOC and DIC in the 60 lakes on the QTP in summer were 58.94 Tg and 6.22 Tg, respectively. Lake area was the most direct factor influencing dissolved carbon storage in lakes on the QTP. Moreover, the TN and pH of the lake water also affected the DOC and DIC storage in the lakes, respectively. Interestingly, the lake pH at 9.1 was an important turning point that caused variations in lake DIC storage. Surprisingly, we found that rivers were able to transport 30 % of the DIC into QTP lakes and were the main source of DIC in the lakes in summer. The findings of this study clarify the sources of dissolved carbon and its drivers and improve our understanding of the carbon cycling processes in the lake system on the QTP.
青藏高原湖泊中环境因素如何影响溶解碳仍不清楚，这限制了人们对湖泊碳循环的理解。在本研究中，对青藏高原夏季的60个湖泊进行了调查，以阐明溶解碳的变化，估算溶解碳储量，并揭示环境因素如何影响溶解碳的变化。青藏高原夏季60个湖泊的溶解有机碳（DOC）和溶解无机碳（DIC）平均含量分别为12.78mg/L和103.66mg/L。盐度和总氮分别是DIC和DOC变化的重要驱动因素。只有当降水量>50mm时，湖泊盐度和温度才会降低，从而影响湖泊溶解碳的变化。重要的是，湖泊的海拔和面积也显著影响湖泊溶解碳的变化。青藏高原夏季60个湖泊中DOC和DIC的总储量分别为58.94Tg和6.22Tg。湖泊面积是影响青藏高原湖泊溶解碳储量的最直接因素。此外，湖水的总氮和pH值也分别影响湖泊中DOC和DIC的储量。有趣的是，pH值为9.1的湖泊是导致湖泊DIC储量变化的一个重要转折点。令人惊讶的是，我们发现河流能够将30%的DIC输送到青藏高原湖泊中，并且是夏季湖泊中DIC的主要来源。本研究的结果阐明了溶解碳的来源及其驱动因素，并增进了我们对青藏高原湖泊系统中碳循环过程的理解。
