Environmental Science and Engineering Seminar
Plate tectonics and climate are two major drivers of the global carbon cycle over geological timescales. In this talk, I will present two studies examining how large earthquakes and a changing climate impact the carbon cycle, with a focus on particulate organic carbon (OC) – an important, yet less-well-understood component in the carbon cycle. The first study will illustrate how the 2008 Mw7.9 great Sichuan earthquake changed the carbon cycle in the eastern Tibetan mountains. Combining river system sampling and geochemical measurement, I found that the earthquake-triggered landslides accelerated OC erosion and burial, leading to an 8x increase in the capacity of the mountain range to draw down atmospheric CO2. The second study will focus on a tributary floodplain of the Yukon River, central Alaska, where the warming climate has largely altered the carbon cycle. In those Arctic floodplains, OC is eroded from permafrost soils and transported by rivers to the ocean for long-term storage. Previous studies suggest that the OC cycling processes are accelerated by warming-induced bank erosion. I will show that significant loss of OC occurred during transfer from soils to rivers, using measurements of sediment and OC samples collected from the studied floodplain. Overall, these two studies provide modern perspectives on how carbon cycle systems respond to changes in tectonics and climate, emphasizing the importance of landforms and geomorphic processes in regulating the OC cycle.