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

我们正在申请资金，以获得一个系统的三个组成部分，以量化北极流域溶解有机物（DOM）的大小分布和元素组成。多年冻土是土壤有机质（SOM）的大量储存，它是大气碳（CO2和CH4）的潜在来源，如果这种有机质分解，可能会导致气候变暖的正反馈。气候变暖正在增加永久冻土的物理扰动和融化，这暴露了以前被掩埋和冻结的SOM池，导致这种有机碳源作为DOM在北极流域的动员和运输。众所周知，许多金属和污染物的生物有效性和毒性，而DOM的生物降解性与其大小有关。然而，很少有人知道的分布，组成或反应的不同大小的部分DOM在加拿大北极。这种知识的缺乏是一个关键的差距，这限制了我们的能力，以评估冻土退化的潜在影响的冻土碳反馈和污染物输送在冻土流域。

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.