Qu Bin, Sillanpää Mika, Li Chaoliu, Kang Shichang, Stubbins Aron, Yan Fangping, Aho Kelly Sue, Zhou Feng, Raymond Peter A
Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli, Finland.
Department of Civil and Environmental Engineering, Florida International University, Miami, Florida, United States of America.
PLoS One. 2017 May 26;12(5):e0178166. doi: 10.1371/journal.pone.0178166. eCollection 2017.
The role played by river networks in regional and global carbon cycle is receiving increasing attention. Despite the potential of radiocarbon measurements (14C) to elucidate sources and cycling of different riverine carbon pools, there remain large regions such as the climate-sensitive Tibetan Plateau for which no data are available. Here we provide new 14C data on dissolved organic carbon (DOC) from three large Asian rivers (the Yellow, Yangtze and Yarlung Tsangpo Rivers) running on the Tibetan Plateau and present the carbon transportation pattern in rivers of the plateau versus other river system in the world. Despite higher discharge rates during the high flow season, the DOC yield of Tibetan Plateau rivers (0.41 gC m-2 yr-1) was lower than most other rivers due to lower concentrations. Radiocarbon ages of the DOC were older/more depleted (511±294 years before present, yr BP) in the Tibetan rivers than those in Arctic and tropical rivers. A positive correlation between radiocarbon age and permafrost watershed coverage was observed, indicating that 14C-deplted/old carbon is exported from permafrost regions of the Tibetan Plateau during periods of high flow. This is in sharp contrast to permafrost regions of the Arctic which export 14C-enriched carbon during high discharge periods.
河网在区域和全球碳循环中所起的作用正受到越来越多的关注。尽管放射性碳测量（14C）有潜力阐明不同河流碳库的来源和循环，但仍有大片区域，如对气候敏感的青藏高原，尚无相关数据。在此，我们提供了来自三条流经青藏高原的亚洲大河（黄河、长江和雅鲁藏布江）的溶解有机碳（DOC）的新14C数据，并展示了青藏高原河流与世界其他河流系统的碳输送模式。尽管在高流量季节流量较高，但由于浓度较低，青藏高原河流的DOC产量（0.41 gC m-2 yr-1）低于大多数其他河流。与北极和热带河流相比，西藏河流中DOC的放射性碳年龄更老/更贫化（距今511±294年，yr BP）。观察到放射性碳年龄与多年冻土流域覆盖率之间存在正相关，这表明在高流量时期，14C贫化/古老的碳从青藏高原的多年冻土区输出。这与北极的多年冻土区形成鲜明对比，北极的多年冻土区在高流量时期输出富含14C的碳。
