Carbon export by erosion of the biosphere: The role of earthquake-triggered landslides

生物圈侵蚀造成的碳输出：地震引发的山体滑坡的作用

• 批准号: NE/P013538/1
• 负责人: Robert Hilton
• 金额: $ 51.1万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP013538%2F1
• 关键词: Carbon; export; erosion; biosphere; role

Does mountain building influence the global carbon cycle and carbon dioxide (CO2) concentrations in the atmosphere, and hence modify Earth's climate? This question is at the heart of a long-standing debate as to how erosion and weathering act to draw down CO2, countering the input of CO2 from volcanoes over millions of years. Earthquakes offer a direct way of removing CO2 from the atmosphere, but how this happens and how large the impact might be has remained poorly understood. Ground shaking during earthquakes can trigger tens of thousands of landslides, which strip large amounts of carbon from soil and plants in mountain forests. Depending on the amount of carbon involved, and what happens to it, earthquakes could be a way in which mountain building drives the global carbon cycle. If the carbon removed from mountain forests reaches rivers, it can be transported in muddy waters downstream and into a long-term sink (storage) of CO2 following burial in sediments. Our research aims to quantify, for the first time, whether large earthquakes could increase the erosion and river export of carbon from mountain forests. Until now, it has proved very challenging to measure the impact of these extreme and unpredictable events in river systems. This is because we need samples collected from rivers before and after earthquakes, in order to use geochemical measurements to fingerprint the carbon source and measure the carbon flux. The research team has recently been involved in the only case where this has been done, after the 2008 Wenchuan earthquake in China which triggered over fifty thousand landslides. There, we found that the carbon flux in a mountain river increased significantly in the four years which followed the earthquake and the associated catastrophic landsliding. Our work from Wenchuan sets the foundation for this research proposal, demonstrating that carbon mobilised by earthquake landslides does reach rivers. However, we expect the impacts to last for ten years, or even hundreds, and Wenchuan is just a single example. It is clear we need other data, and a new approach in order to fill this research gap. We will study multiple large earthquakes, and make measurements over decades to centuries before and after each earthquake. To do this, we will combine landslide maps from historical earthquakes around the world, with some of the best studied records of sediment export following large earthquakes in lakes. The well-dated and well-understood lake sediment records come from the western Southern Alps, New Zealand. They record the response of the mountain landscape to four large earthquakes over a thousand years. We will use geochemistry techniques to fingerprint and track the carbon sourced from vegetation and soil (rather than eroded from bedrock) and combine these with measurements of sediment flux to calculate carbon flux. This can be done for four earthquakes in two lakes, as well as during the 'background' periods before and long after the catastrophic landsliding. The datasets will allow us to confidently quantify how earthquakes increase carbon export from forests from a 'background' state. We will use the new data and our understanding of the main processes operating to build a model to allow us to assess the role of earthquakes for carbon flux in mountains on longer timescales. For the first time, we will be able to apply the model around the world to mountains which experience earthquakes. We will account for changing earthquake size and how often they happen, and the amount of carbon in the forest and the rate at which it is degraded in landslide deposits. We will also consider how different rainfall patterns in river catchments can change the flux of carbon. With these novel insights, we will be able to quantify how earthquakes impact the carbon cycle, CO2 and the evolution of Earth's climate.

造山是否会影响全球碳循环和大气中二氧化碳(CO2)的浓度，从而改变地球气候？这个问题是关于侵蚀和风化如何作用于吸收二氧化碳，抵消数百万年来火山输入的二氧化碳的长期辩论的核心。地震提供了一种直接从大气中消除二氧化碳的方法，但这种情况是如何发生的，影响可能有多大，人们仍然知之甚少。地震期间的地面震动会引发数以万计的山体滑坡，山林中的土壤和植物中的大量碳被剥离。地震可能是造山推动全球碳循环的一种方式，这取决于涉及的碳量及其发生的情况。如果从山林中移走的碳到达河流，它可以在下游的泥水中运输，并在埋藏在沉积物中后进入长期的二氧化碳下沉(储存)。我们的研究旨在首次量化大地震是否会增加山林中碳的侵蚀和河流输出。到目前为止，衡量这些极端和不可预测的事件对河流系统的影响是非常具有挑战性的。这是因为我们需要从地震前和地震后的河流中收集样本，以便使用地球化学测量来确定碳源并测量碳通量。该研究小组最近参与了唯一一起这样做的案例，那是在2008年中国汶川地震引发5万多起山体滑坡之后。在那里，我们发现，在地震和与之相关的灾难性山体滑坡之后的四年里，一条山区河流的碳通量显著增加。我们来自汶川的工作为这项研究计划奠定了基础，证明了地震泥石流动员的碳确实到达了河流。然而，我们预计影响将持续十年，甚至数百年，汶川只是一个例子。显然，我们需要其他数据，需要一种新的方法来填补这一研究空白。我们将研究多次大地震，并在每次地震前后进行数十年至数百年的测量。要做到这一点，我们将结合世界各地历史地震的滑坡地图，以及一些研究最好的湖泊大地震后沉积物输出的记录。这些年代悠久、广为人知的湖泊沉积物记录来自新西兰的南阿尔卑斯山西部。它们记录了一千年来山脉景观对四次大地震的反应。我们将使用地球化学技术对来自植被和土壤(而不是从基岩侵蚀)的碳进行指纹和跟踪，并将这些与沉积物通量的测量相结合来计算碳通量。对于两个湖泊中的四次地震，以及在灾难性山体滑坡之前和很长一段时间后的背景时期，都可以做到这一点。这些数据集将使我们能够自信地量化地震是如何增加森林中的碳从背景状态输出的。我们将使用新的数据和我们对主要运行过程的理解来建立一个模型，使我们能够在更长的时间尺度上评估地震对山区碳通量的作用。我们将第一次能够将该模型应用于世界各地经历地震的山脉。我们将考虑地震规模和发生频率的变化，以及森林中的碳量和滑坡堆积物中碳素的降解速度。我们还将考虑河流集水区不同的降雨模式如何改变碳通量。有了这些新颖的见解，我们将能够量化地震如何影响碳循环、二氧化碳和地球气候的演变。

项目成果

Seismic cycles, earthquakes, landslides and sediment fluxes: Linking tectonics to surface processes using a reduced-complexity model

• DOI: 10.1016/j.geomorph.2019.04.017
• 发表时间: 2019-08-15
• 期刊: GEOMORPHOLOGY
• 影响因子: 3.9
• 作者: Croissant, Thomas;Steer, Philippe;Hilton, Robert G.
• 通讯作者: Hilton, Robert G.

Post-seismic evolution of organic carbon mobilised by landsliding

滑坡移动有机碳的震后演化

• 发表时间: 2018
• 作者: Croissant T

Carbon export from mountain forests enhanced by earthquake-triggered landslides over millennia

• DOI: 10.1038/s41561-018-0216-3
• 发表时间: 2018-10-01
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Frith, Nicole, V;Hilton, Robert G.;Densmore, Alexander L.
• 通讯作者: Densmore, Alexander L.

Post-seismic export of organic carbon - a reduced-complexity approach

震后有机碳输出 - 一种降低复杂性的方法

• 发表时间: 2019
• 作者: Croissant T

The role of landslides in mobilising organic carbon from the biosphere in the Southern Alps, New Zealand

新西兰南阿尔卑斯山山体滑坡在调动生物圈有机碳方面的作用

• 发表时间: 2018
• 作者: Harvey E