Breaking down the permafrost carbon feedback enigma: characterizing the composition and lability of dissolved organic carbon (DOC) according to size fractions

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We are requesting funding to acquire three integral components of a system to quantify the size distribution and elemental composition of dissolved organic matter (DOM) in Arctic watersheds. Permafrost soils represent a large store of soil organic matter (SOM), which represents a potential source of atmospheric carbon (CO2 and CH4) that could result in a positive feedback on climate warming if this organic matter is subject to decomposition. Climate warming is increasing the physical disturbance and thaw of permafrost, which is exposing previously buried and frozen pools of SOM, leading to mobilization and transport of this source of organic carbon as DOM in Arctic watersheds. It is well known that the bioavailability and toxicity of many metals and contaminants, and the biodegradability of DOM is related to its size. Yet very little is known about the distribution, composition or reactivity of different size fractions of DOM across the Canadian Arctic. This lack of knowledge is a critical gap, that limits our ability to assess the potential impact of permafrost degradation on both the permafrost carbon feedback and contaminant transport in permafrost watersheds.