The role of earthquakes and storms in the fluvial export of terrestrial organic carbon along the eastern margin of the Tibetan plateau: A biomarker perspective
The role of earthquakes and storms in the fluvial export of terrestrial organic carbon along the eastern margin of the Tibetan plateau: A biomarker perspective
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DOI：
10.3389/feart.2022.1090983
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
Jin Wang;Tian Ma;Fei Zhang;R. Hilton;Xiaojuan Feng;Zhangdong Jin
中科院分区：
文献类型：
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作者：
Jin Wang;Tian Ma;Fei Zhang;R. Hilton;Xiaojuan Feng;Zhangdong Jin
在地震和强降雨的驱动下，陡峭的构造活动山脉是陆地有机碳从土壤、岩石和植被中通过滑坡进入河流的热点。来自不同来源的有机碳的后续输送和河流流动可在一系列时间尺度上影响大气中的CO2浓度。极端滑坡触发事件可以提供有关碳输出过程和速率的见解。本文利用2005 - 2012年在青藏高原东缘的长江支流岷江上游采集的悬浮沉积物，比较了2008年汶川地震前后和2005年暴雨泥石流事件前后陆地有机碳的侵蚀。为了限制河流颗粒有机碳（POC）的来源，我们量化了悬浮沉积物，集水土壤和滑坡沉积物中的木质素酚和正链烷酸。我们发现，河流POC有较高的输入少降解，离散的有机物在高悬浮泥沙负荷，而POC的来源似乎随机在低悬浮泥沙浓度。2005年的泥石流动员了大量的POC，导致一天内输出的木质素相当于正常年份。相比之下，2008年汶川地震增加了POC和颗粒木质素的通量，尽管与季节变化相比，对POC来源的影响有限。我们的研究结果突出了重要作用的情景事件在河流输出陆地碳。
Driven by earthquakes and intense rainfall, steep tectonically active mountains are hotspots of terrestrial organic carbon mobilization from soils, rocks, and vegetation by landslides into rivers. Subsequent delivery and fluvial mobilization of organic carbon from different sources can impact atmospheric CO2 concentrations across a range of timescales. Extreme landslide triggering events can provide insight on processes and rates of carbon export. Here we used suspended sediment collected from 2005 to 2012 at the upper Min Jiang, a main tributary of the Yangtze River on the eastern margin of the Tibetan Plateau, to compare the erosion of terrestrial organic carbon before and after the 2008 Wenchuan earthquake and a storm-derived debris flow event in 2005. To constrain the source of riverine particulate organic carbon (POC), we quantified lignin phenols and n-alkanoic acids in the suspended sediments, catchment soils and landslide deposits. We found that riverine POC had higher inputs of less-degraded, discrete organic matter at high suspended sediment loads, while the source of POC seemed stochastic at low suspended sediment concentrations. The debris flow in 2005 mobilized a large amount of POC, resulting in an export of lignin within a single day equivalent to a normal year. In comparison, the 2008 Wenchuan earthquake increased the flux of POC and particulate lignin, albeit with limited impact on POC sources in comparison to seasonal variations. Our results highlight the important role of episodic events in the fluvial export of terrestrial carbon.