Total organic carbon (TOC) analyzer for characterizing carbon, mercury, and microbial dynamics across peatland and forest ecosystems

加拿大北寒带和亚北寒带的森林和泥炭地特别重要，因为它们将大量的大气二氧化碳作为有机物质储存在土壤中，否则将导致全球变暖，含有大量的世界可饮用淡水，并支持林业和泥炭自然资源工业。在这些生态系统中，土壤碳(C)、温室气体动态、生态系统管理和水质之间的联系是不可分割的。土壤微生物缓慢而不完全地分解顽固的植物物质，特别是在洪水或潮湿条件下，导致溶解有机碳（DOC）的产生，这代表了生态系统中大量的、往往无法计算的碳损失，并作为整个集水区泥炭地、高地和水生系统之间的生物地球化学联系。甲基汞（MeHg）是这些生态系统中的一种重要污染物，具有环境和人类健康后果。在DOC产量最大的厌氧湿地土壤和水生环境中，汞通过厌氧微生物活动甲基化。最近的证据表明，DOC是将汞转运到特定甲基化位置的重要载体，与DOC结合可能进一步提高生物利用度。越来越清楚的是，为了了解汞的运输和生物放大，我们必须表征整个流域的DOC动态。我们正在申请用于DOC表征的总有机C分析仪的资金，这将使我们能够测量土壤分解过程的速率，加拿大北部森林和湿地生态系统中对汞运输很重要的C转移，以及负责有机物质矿化和这些生态系统中温室气体释放的土壤微生物群落的C底物生物有效性和生物量。

The patterned forest and peatland boreal and sub-boreal regions of Canada are exceptionally important because they store vast amounts of atmospheric carbon dioxide as organic matter in soils that otherwise would contribute to global warming, contain a large volume of the world's potable freshwater, and support forestry and peat natural resource industries. Links between soil carbon (C), greenhouse gas dynamics, ecosystem management, and water quality are inextricable in these ecosystems. Slow, incomplete decomposition of recalcitrant plant material by soil microorganisms, particularly under flooded or wet conditions, results in the production of dissolved organic carbon (DOC) that represents significant and often unaccounted C losses from ecosystems and serve as a biogeochemical link between peatland, upland, and aquatic systems throughout catchments. Methylmercury (MeHg) is an important pollutant in these ecosystems with environmental and human health consequences. In anaerobic wetland soils and aquatic environments where DOC production is greatest, Hg is methlyated through anaerobic microbial activity. Recent evidence has suggested that DOC is an important vector for transporting Hg to specific locations of methylation and binding with DOC may further increase bioavailability. It is becoming clear that in order to understand transport and biomagnification of Hg, we must characterize DOC dynamics throughout watersheds. We are requesting funds for a total organic C analyzer for DOC characterization that will allow us to measure rates of soil decomposition processes, C transfer across northern Canadian forest and wetland ecosystems that are important for Hg transport, and C substrate bioavailability to, and biomass of, soil microbial communities that are responsible for mineralization of organic matter and release of greenhouse gasses from these ecosystems.