Quantifying The Impact of Recent Climate Change on Sedimentary Biogeochemical Cycles and The Organic Carbon Sink

全球变暖正在改变北极环境中陆地和海洋有机碳（OC）的储存和释放。为了了解气候变化如何影响北极的碳循环，有必要了解它从永久冻土融化释放到最终目的地的过程，在大气中或在海底。麦肯齐流域和博福特陆架是受北极气候变化影响的关键地区，这可能是更广泛的北极地区将发生什么的一个指标。当永久冻土融化时，它会释放出已经冻结了数千年的有机碳。生活在土壤、湖泊、溪流和海洋中的微生物可以利用这些OC来生长，将其降解为二氧化碳或甲烷等温室气体（GHG），从而导致更多的变暖和更多的融化，这是一个正反馈。微生物利用电子受体，如氧、硝酸盐、锰、氧化铁和硫酸盐来降解OC。在海底，OC很可能会降解成二氧化碳。在陆地上，电子受体通常是稀缺的，微生物将OC发酵成甲烷气体，这是一种更强的温室气体。因此，降低OC的地点和途径对气候有直接影响，并可能加剧变暖。生物地球化学循环的快速变化已被观察到，以响应最近的变暖趋势，这可能影响OC的降解。我的长期研究目标是预测微生物-沉积系统与北极变化之间的响应和反馈。两个短期（5年）的科学目标是：(1)量化波弗特陆架有机碳矿化的现在和历史分布以及海洋和陆地来源的命运；(2)平衡温室气体生产和排放的碳预算，这些温室气体来自经历永久冻土突然融化的地点。(1)和(2)都处于北极研究的前沿，由于新技术的发展和微调以及多学科国际合作，可以通过实验获得。分析程序依赖于从现场取样孔隙水、沉积物和气体，以及在实验室用稳定和放射性同位素示踪剂分析微生物分解代谢率。然后将结果纳入考虑沉积速率、孔隙水中的化学通量和气体运移的成岩模型。碳和硫的稳定同位素在这一分析中起着关键作用。该项目将预测麦肯齐-博福特河流系统碳汇的变化。它与泛北极地区对有机碳运输、掩埋和退化的评估有关。这可能会影响政府政策和北极国家之间的关系。该项目是9个HQP的试验场，将提高他们与当地社区一起进行尊重研究的能力。它将使加拿大保持北极科学研究的前沿地位，并在评估气候变化后果方面处于领先地位。

Global warming is modifying the storage and release of organic carbon (OC) in the Arctic environment both on land and at sea. To understand how climate change influences the Arctic carbon cycle, it is necessary to understand its journey from release by permafrost thaw to final destination, in the atmosphere or in the seafloor. The Mackenzie watershed and Beaufort Shelf is a key region that is affected by changing Arctic conditions and which may be an indicator of what will happen across the broader Arctic. When permafrost thaws, it releases OC that has been accumulating frozen for thousands of years, all at once. Microbes living in soil, lakes, streams and the sea, can then use this OC to grow by degrading it into greenhouse gases (GHG) such as carbon dioxide or methane, leading to more warming and, more thaw, in a positive feedback. Microbes use electron acceptors such as oxygen, nitrate, manganese, iron oxides and sulfate to degrade OC. In the seafloor, OC is likely to degrade into carbon dioxide. On land, electron acceptors are often scarce and microbes ferment OC into methane gas, which is a more potent greenhouse gas. The place, and the pathway taken to degrade OC therefore has a direct impact on the climate and can exacerbate warming. Rapid shift in biogeochemical cycles, have been observed in response to the recent warming trends, which may affect OC degradation. My long-term research goal is to forecast the responses and feedbacks between microbial-sedimentary systems and the changing Arctic. Two short-term (5-year) science objectives are (1) quantify the present and the historical distribution of organic carbon (OC) mineralization on the Beaufort shelf and the fate of marine and terrestrial sources and (2) balance the carbon budgets of production and emissions of greenhouse gases from sites undergoing abrupt permafrost thaw. Both (1) and (2) are at the forefront of Arctic research and are experimentally accessible due to the development and fine-tuning of new techniques and multidisciplinary international collaborations. The analytical program relies on the sampling of porewater, sediment and gas from field sites and analysis of microbial catabolic rates with both stable and radioactive isotope tracers in the lab. Results are then incorporated in diagenetic models that considers deposition rates, chemical fluxes in porewater and gas migration. Stable isotopes of carbon and sulfur play a critical role in this analysis. The program will anticipate changes in the carbon sink of the Mackenzie-Beaufort fluvial system. It ties into pan-Arctic assessments of OC transport, burial and degradation. This could shape government policy and relations between Arctic nations. The program is the proving ground for nine HQP that will increase their capacity to conduct respectful research alongside local communities. It will maintain Canada at the forefront of Arctic scientific research and a leader in assessing the consequences of climate change.