Himalayan chemical weathering and carbon transfer triggered by the April 2015 Nepal Earthquake

尼泊尔最近发生的地震从人道主义角度来看是毁灭性的，但也对地球表面环境产生了深刻影响。地震期间地面运动的主要影响之一是它破坏了尼泊尔喜马拉雅山谷陡峭的山坡的稳定。这导致了重大的山体滑坡，其中一些已经大到足以筑坝河流。这些山体滑坡导致细粒岩石物质产生巨大的脉冲，输送到河流中，导致河流中的泥沙脉冲。这是一个活跃的研究领域。泥沙负荷增加会导致洪水，但我们感兴趣的是细粒泥沙是如何溶解的。这是因为沉积物的溶解对百万年的碳循环有重大影响。尽管这种时间尺度上的碳循环看起来可能很神秘，但理解它是至关重要的，因为正是这种长期的碳循环将地球表面的气候维持在一个狭窄的窗口内，最终使生命得以发展和维持。碳和岩石溶解是联系在一起的，因为岩石溶解的主要方式是通过碳酸，碳酸是大气中的二氧化碳溶解在水中。当碳酸溶解岩石时，它变成中和的碳酸氢盐，这是一种存在于所有自然水域中的碳(例如，检查矿泉水瓶的标签)。水中的碳酸氢盐通过河流转移到海洋中，最终转化为石灰岩，永久锁定二氧化碳。岩石溶蚀的主要控制因素是侵蚀作用对泥沙的补给作用，而滑坡是其中最重要的作用之一。我们预计，尼泊尔地震引发的数以千计的山体滑坡将在未来12个月内通过岩石溶解导致碳转移的巨大脉冲，然后材料将被季风降雨冲刷出系统。我们提议在未来12个月内与一系列国际合作伙伴一起收集尼泊尔的河水和沉积物样本，以试图更好地了解地震对碳循环造成的扰动。

The recent Nepalese earthquakes are devastating from a humanitarian perspective, but also have a profound impact on the surface environment of the Earth. One of the major impacts of the ground movement during the Earthquakes is that it destabilises the steep hillsides in the Himalayan valleys of Nepal. This causes major landslides, some of which have been big enough to dam rivers. These landslides cause a massive pulse in fine grained rock material that is delivered into rivers, causing a pulse of sediment in the rivers. This is an active field of research. Increased sediment load can cause flooding, but our interest stems from how that fine grained sediment dissolves. This is because the dissolution of sediment has a major influence on the million year carbon cycle. Although the carbon cycle on such time-scales might seem esoteric, it is critical to understand because it is this long-term carbon cycle that has maintained the climate at the surface of the Earth within a narrow window, ultimately allowing life to develop and be sustained. Carbon and rock dissolution are linked because the main way in which rocks dissolve is via carbonic acid, which is CO2 from the atmosphere dissolved in water. When the carbonic acid dissolves rocks, it becomes neutralised as bicarbonate, a form of carbon that is present in all natural waters (check the label of a mineral water bottle for example). This bicarbonate in waters gets transferred to the oceans by rivers, where ultimately it gets converted to limestone, locking down CO2 permanently. The dominant control on rock dissolution is the supply of sediment via erosion processes, of which land sliding is one of the most important. We expect that the thousands of landslides triggered by the Nepal earthquakes will cause a massive pulse in carbon transfer via rock dissolution over the next 12 months, before the material gets washed out the system by the monsoon rainfalls. We are proposing to collect river water and sediment samples in Nepal, over the next 12 months with a series of international partners to try and better understand the perturbation that an earthquake will have caused to the carbon cycle.