Biogeochemical cycles of climate-active gases CH4, N2O and DMS in Arctic and Subarctic Marine Waters

北极和亚北极海洋沃茨在控制影响地球气候的各种气体的大气浓度方面发挥着重要作用。 甲烷（CH 4）和一氧化二氮（N2 O）是使地球变暖的强效温室气体，而二甲基硫（DMS）是海洋微生物产生的一种微量气体，它促进了云和大气气溶胶的形成，这些气溶胶反向散射入射的太阳辐射并使地球降温。 这些“气候活跃”气体的浓度和海-气交换受到物理、化学和生物过程相互作用的影响，并对气候驱动的海洋条件变化敏感。 目前，这些潜在的依赖气候的变化的规模受到直接观测的限制。拟议的研究方案将收集关于表层海洋沃茨中二甲基硫、甲烷和氧化亚氮的浓度和生物/化学循环的基本数据。主要的研究目标是：1）量化这些气体在北极和亚北极海洋沃茨在各种海洋条件下的空间和时间变化; 2）使用同位素标记实验来量化DMS，CH 4和N2 O循环中的关键生产和消费速率。 这项工作的结果将促进我们对未来几十年海洋生产这些气体的潜在气候依赖性变化的理解。 将利用船载实地调查绘制亚北极太平洋沿海和近海沃茨以及加拿大北冰洋的甲烷、氧化亚氮和二甲基硫的浓度图。 测量将使用我们在过去十年中开发的一套分析方法进行。 同位素标记实验将用于跟踪DMS通过各种途径的生产和消费，并量化CH 4和N2 O通过不同前体化合物的循环。 拟议的工作的结果将提供新的机制的洞察力的因素调节海洋甲烷，N2 O和DMS浓度，及其对气候敏感的变量的潜在反应。 反过来，这将对理解全球气候系统的未来演变具有重要意义。

Arctic and Subarctic marine waters play a large role in controlling the atmospheric concentration of various gases that influence Earth's climate. Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases acting to warm the planet, while dimethylsulfide (DMS), a trace gas produced by marine microbes, promotes the formation of clouds and atmospheric aerosols that back-scatter incoming solar radiation and act to cool the planet. The concentration and sea-air exchange of these 'climate-active' gases are influenced through the interplay of physical, chemical and biological processes, and sensitive to climate-driven shifts in oceanic conditions. At present, the magnitude of these potential climate-dependent changes is poorly constrained by direct observations. The proposed research program will collect fundamental data on the concentrations and biological / chemical cycles of DMS, CH4 and N2O in surface ocean waters. The principle research objectives are to: 1) quantify the spatial and temporal variability of these gases in Arctic and Subarctic marine waters across a range of oceanographic conditions; and 2) use isotope-labeling experiments to quantify the rates of key production and consumption in the DMS, CH4 and N2O cycles. The results from this work will advance our understanding of potential climate-dependent changes in the oceanic production of these gases over the coming decades. Ship-based field surveys will be used to map the concentrations of CH4, N2O and DMS in coastal and offshore waters of the Subarctic Pacific, and in the Canadian Arctic Ocean. Measurements will be conducted using a suite of analytical methods we have developed over the past decade. Isotope labeling experiments will be used to follow the production and consumption of DMS through various pathways, and quantify the cycling of CH4 and N2O through different precursor compounds. The results of the proposed work will provide new mechanistic insight into the factors regulating oceanic CH4, N2O and DMS concentrations, and their potential response to climate-sensitive variables. This, in turn, will be of great relevance to understanding the future evolution of the global climate system.