Carbon gas dynamics in aquatic ecosystems: integrating physical processes and biogeochemical cycling

我研究的中心目标是建立一个可靠的定量框架，以评估内陆水域在从地方到全球的景观C预算中的作用。我们小组和其他地方最近的研究已经确定CH4是一个重要的参与者。由于甲烷的生物地球化学循环的性质比二氧化碳复杂得多，对其目前对温室气体排放总量的贡献的估计仍然很松散。然而，由于其高增温潜势和温度敏感性，其未来的作用可能更为重要，但更难以预见。我认为，评估和预测其贡献的部分困难在于缺乏一个物理-生物地球化学框架来整合主要通量，即生产途径、运输机制、氧化程度和最终逃逸到大气中。拟议的研究计划围绕几个侧重于甲烷动力学的子项目进行阐述，重点是物理限制对生物地球化学过程速率的影响。该研究将首先在一个模型湖（L. Croche）上进行，然后扩展到覆盖生态系统大小、形状和营养状况梯度的代表性湖泊的横截面。我们还将进行详细的调查，以进一步了解排放的一个关键组成部分，气体交换（k600），重点是它所起的生态作用。总之，研究计划的这些组成部分将提供必要的框架，以更好地了解湖泊中的CH4动态，最终将导致更好地预测水生生态系统的CH4排放。

The central goal of my research is to establish a solid quantitative framework to assess the role of inland waters in landscape C budgets, from local to global. Recent research by our group and elsewhere has identified CH4 as a significant player. Owing to the much more complex nature of the biogeochemical cycling of methane relative to CO2, estimates of its current contribution to total GHG emissions are still loosely constrained. However, with its high warming potential and temperature sensitivity, its future role is potentially much more important but even less foreseeable. I contend that part the difficulty in assessing and predicting its contribution is the lack of a physical-biogeochemical framework in which to integrate the main fluxes, namely production pathways, transport mechanisms, degree of oxidation and ultimately evasion to the atmosphere. The proposed research program is articulated around several sub-projects focussing on methane dynamics with an emphasis on the role played by physical constraints impinging on the rates of biogeochemical processes. The study will first be conducted on a model lake (L. Croche) and then be extended to a cross section of representative lakes covering gradients of ecosystem size, shape and nutrient status. We will also conduct detailed investigations to further our understanding of a key component of emission, gas exchange (k600), with an emphasis on the ecological role it plays. Together, these components of the research program will provide the necessary framework to better understand CH4 dynamics in lakes that will ultimately lead to the better predictions of CH4 emission from aquatic ecosystems.