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。永久冻土层是土壤有机质（SOM）的一大储藏库，是大气碳（CO2和CH4）的潜在来源，如果这些有机质被分解，可能会对气候变暖产生正反馈。气候变暖加剧了永久冻土的物理扰动和解冻，使以前埋藏和冻结的有机质池暴露出来，导致这种有机碳源在北极流域以DOM的形式被动员和运输。众所周知，许多金属和污染物的生物利用度和毒性，DOM的生物可降解性与其大小有关。然而，人们对加拿大北极地区不同大小的DOM的分布、组成或反应性知之甚少。这种知识的缺乏是一个关键的缺口，它限制了我们评估永久冻土退化对永久冻土碳反馈和永久冻土流域污染物运输的潜在影响的能力。

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.