Tracking changes in organic matter reservoirs in boreal forest landscapes

有机物质从陆地环境向水生环境的迁移及其在内陆水域的循环是全球碳循环的一个重要组成部分。在这些环境中，调节土壤和溶解有机质的反应性的因素传统上是孤立地研究的，仍然知之甚少--阻碍了对这些水库在调节气候的反馈中所起作用的预测性理解。OM的形成和命运在很大程度上取决于在短时间尺度上活动的微生物的活动--然而，这些活动具有十年和百年的影响。因此，我们对这些有机质储集层的理解需要将水生和陆地生物地球化学概念结合起来，并提高我们将地球化学工具与微生物活动联系起来的能力，以解决这些概念。北方有机质在气候反馈中的潜在作用是重要的，因为北方地区拥有全球土壤碳的30%，预计在下个世纪将经历一些最严重的变暖。这项研究计划将重点放在可能控制北方森林景观中的有机质水库的关键生物地球化学机制上。将进行研究，以评估：(1)有机质来源、组成和化学计量对通过水系微生物生物膜呼吸损失溶解的有机质的作用，(2)微生物输入到土壤有机质池的周转，(3)调节微生物生物标记物稳定碳同位素解释的因素--微生物生物标志物是评估天然OM样品中微生物底物使用的关键工具，以及(4)气候变暖如何调节每种因素。这项研究将沿着研究地点的既定气候梯度进行，其他政府和大学研究人员正在进行补充研究。这将促进拟议的研究，并促进学生与直接参与环境管理和政策的省级和加拿大政府研究人员之间的互动。因此，拟议的研究将成为培养本科生和研究生成为能够提出和回答相关地球科学问题的高技能、独立研究人员的特殊手段。

The movement of organic matter (OM) from the terrestrial to aquatic environment and its cycling within inland waters is a significant component of the global carbon cycle. Factors regulating the reactivity of soil and dissolved OM across these environments has traditionally been studied in isolation and remains poorly understood- preventing a predictive understanding of the role these reservoirs play in feedbacks regulating climate. The formation and fate of OM depends largely upon activity of microorganisms operating on short-time scales- yet these activities have decadal and centennial ramifications. Therefore, our understanding of these OM reservoirs requires the coupling of aquatic and terrestrial biogeochemical concepts and improving our ability to link geochemical tools to microbial activities to address these concepts. The potential role for boreal OM in climate feedbacks is significant given the boreal region holds >30% of the global soil carbon and is expected to experience some of the greatest warming over the next century. This research program will focus on key biogeochemical mechanisms potentially controlling OM reservoirs in boreal forest landscapes. Studies will be conducted to assess; (1) The role of OM source, composition and stoichiometry on the loss of dissolved OM via stream microbial biofilm respiration, (2) Turnover of microbial inputs to soil OM pools, (3) The factors regulating the interpretation of the stable carbon isotopes of microbial biomarkers- a critical tool for assessing microbial substrate use in natural OM samples, and (4) How each of these may be regulated by climate warming. This research will be conducted along an established climate gradient of study sites where other governmental and university researchers are conducting complementary research. This will facilitate the proposed research and also promote interactions between students and provincial and Canadian government researchers directly involved in environmental management and policy. The studies proposed will, therefore, serve as an exceptional means for training undergraduate and graduate students to become highly skilled, independent researchers who can ask and answer relevant earth science questions.