The biogeochemistry and ecology of Arctic aquatic ecosystems

覆盖加拿大一半陆地的永久冻土正在整个北极地区融化。这种变化对我们北部景观的影响之一是，目前被“锁”在冻土中的碳(C)和其他成分可以在土壤中发生反应，并从土壤中释放出来，并运输到水生环境。我们计划在加拿大西部北极地区开展工作，研究永久冻土融化过程中溶解无机和溶解有机碳（DIC， DOC）从陆地到水生环境的变化，以及这种变化的影响。DIC和DOC都是整个C循环的核心组成部分，但效果却截然不同。一方面，DIC通常代表大气中的CO2汇：碳酸氢盐（HCO3-）通常是水生DIC库的最大组成部分，主要由化学风化产生，其中溶解在水中的CO2（碳酸）驱动与岩石或矿物土壤的化学反应，并使原始CO2“固定”为HCO3-。相比之下，在阳光或细菌将DOC降解为CO2之后，通过土壤有机C在水中的溶解而从永久冻土中动员起来的DOC代表了未来的CO2来源。这些过程意义重大：虽然风化作用是陆地上两种主要的二氧化碳封存机制之一，但永久冻土封存的有机碳大约是目前大气中存在的二氧化碳的两倍。本研究将量化化学风化随永久冻土融化的变化，永久冻土DOC对矿物土壤捕获和阳光和细菌降解的敏感性，以及DIC生成和DOC释放的C平衡如何相互抵消。因此，它将有助于我们理解北方水生碳循环的未来轨迹，特别关注一个地区（加拿大北极西部），那里变暖强烈，永久冻土融化正在导致大规模的融化滑坡。这项工作将培养出许多高素质的人才。它还将具体地将北方的培训和北方的知识纳入研究工作，并促进与北方社区的联系，使北方能够对这项工作作出投入和反馈。

Permafrost, which covers about half of Canada's landmass, is thawing throughout the Arctic. One of the results of this change to our northern landscapes is that the carbon (C), and other constituents currently 'locked away' (sequestered) in frozen ground are becoming available for reaction within and liberation from soils, and transport to aquatic environments. We are proposing to work in the western Canadian Arctic to investigate changes in the delivery of dissolved inorganic and dissolved organic C (DIC, DOC) from land to the aquatic environment with permafrost thaw, and the implications of this change. Both DIC and DOC are central components of the overall C cycle, but with contrasting effect. On the one hand, DIC typically represents an atmospheric CO2 sink: bicarbonate (HCO3-), generally the largest component of the aquatic DIC pool, is mainly produced by chemical weathering, whereby CO2 dissolved in water (carbonic acid) drives chemical reactions with rock or mineral soils, and causes the original CO2 to become 'fixed' as HCO3-. In contrast, the DOC that is mobilized from permafrost soils by the dissolution of soil organic C in water represents a future CO2 source, following DOC degradation to CO2 by sunlight or bacteria. These processes are significant: while weathering is one of the two primary CO2 sequestration mechanisms on land, about twice as much organic C is sequestered by permafrost as currently exists in the atmosphere as CO2. This research will quantify changes in chemical weathering with permafrost thaw, the susceptibility of permafrost DOC to capture by mineral soils and degradation by sunlight and bacteria, and how the C balance of DIC creation and DOC liberation offset each other. As such, it will aid in our understanding of the future trajectory of the northern aquatic C cycle, focusing specifically on a region (the western Canadian Arctic) where warming is intense and permafrost thaw is causing massive thaw slumps. This work will result in the training of numerous highly qualified personnel. It will also specifically integrate northern training and northern knowledge into the research endeavour, and facilitate outreach to northern communities to enable northern input to, and feedback on, this work.