Insights into biogeochemical transformations and fluxes from high-frequency ocean time-series data.

从高频海洋时间序列数据中洞察生物地球化学转变和通量。

• 批准号: RGPIN-2021-04332
• 负责人: Wallace, Douglas
• 金额: $ 3.72万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=761603
• 关键词: Insights; into; biogeochemical; transformations; fluxes

The research will examine ocean cycling of carbon, nitrogen, oxygen and iodine. Oxygen and carbon will be studied in the Labrador Sea, where wintertime deep mixing creates potential for rapid, climate-sensitive transfer of oxygen, anthropogenic CO2 and organic carbon to the ocean interior. The cycling of nitrogen and iodine will be studied in Bedford Basin, Nova Scotia, a 70m deep coastal fjord, adjacent to Halifax. The research will be based on time-series of chemical, physical and biological parameters from: a) an autonomous, multidisciplinary observatory in the deepwater formation region of the Labrador Sea which is a key region for delivery of O2 and anthropogenic CO2 to the deep ocean; b) a multidisciplinary, weekly time-series from the seasonally-stratified Bedford Basin, whose nitrogen cycle is impacted by humankind and in which both nitrogen and iodine undergo major seasonal transformation. Deployment of the SeaCycler profiling winch and sensor package in the Labrador Sea (summer 2021), will provide high-resolution profiles (0-150m; 1-4 times per day for a year) of bio-optical properties, dissolved gases (CO2 and O2), nitrate, phosphate, temperature, salinity and turbulence, as well as estimates of zooplankton biomass. The SeaCycler will be operated in parallel with fixed-depth measurement of pH, alkalinity, pCO2 at a nearby mooring which will also be equipped (by other investigators) with a phytoplankton sampler allowing species succession to be related to chemical/physical data. HQP will use the new data as well as data from an earlier deployment to examine: 1) the fraction of net community production exported to the deep ocean by winter mixing (compared to settling via the biological carbon pump); 2) factors that explain the timing of the spring bloom; 3) the organic carbon export efficiency after seasonal stratification, based on nutrient, carbon and oxygen budgets above and below the euphotic zone. Given constrained exchanges and manageable size, Bedford Basin has characteristics of a large natural mesocosm so that time-series allow detailed examination of processes underlying speciation changes as well as fluxes of nitrogen and iodine. The time-series will provide context for the HQP projects which will involve repeated, short-term experimental manipulations to test and refine understanding and parameterization of chemical and microbially-mediated transformations (e.g. nitrification; iodate reduction). In both locations, the time-series provide an environment for multidisciplinary teams of HQP to work on complementary projects. The research will deliver: (a) tests, with comprehensive in-situ data, of diverse hypotheses for initiation of spring phytoplankton blooms, debated since the 1950's; (b) understanding of the sensitivity to climate change of organic carbon and oxygen delivery to the deep ocean via deep-mixing; (c) understanding of controls of nitrogen and iodine speciation and fluxes in the coastal ocean.

该研究将研究碳、氮、氧和碘的海洋循环。氧气和碳将在拉布拉多海进行研究，那里的冬季深度混合创造了将氧气、人为二氧化碳和有机碳快速、气候敏感地转移到海洋内部的潜力。氮和碘的循环将在新斯科舍省贝德福德盆地进行研究，该盆地是一个 70m 深的沿海峡湾，毗邻哈利法克斯。该研究将基于以下化学、物理和生物参数的时间序列：a）位于拉布拉多海深水形成区域的一个自主、多学科观测站，该区域是向深海输送氧气和人为二氧化碳的关键区域; b) 来自季节性分层贝德福德盆地的多学科每周时间序列，该盆地的氮循环受到人类的影响，其中氮和碘都经历了重大的季节性转变。在拉布拉多海部署 SeaCycler 剖面绞车和传感器套件（2021 年夏季），将提供生物光学特性、溶解气体（CO2 和O2）、硝酸盐、磷酸盐、温度、盐度和湍流，以及浮游动物生物量的估计。 SeaCycler 将与附近停泊处的 pH、碱度、pCO2 固定深度测量同时运行，该停泊处还将（由其他研究人员）配备浮游植物采样器，使物种演替与化学/物理数据相关。 HQP 将使用新数据以及早期部署的数据来检查：1）通过冬季混合导出到深海的净群落产量的比例（与通过生物碳泵沉淀相比）； 2）解释春季开花时间的因素； 3) 季节性分层后的有机碳输出效率，基于亮光带上方和下方的养分、碳和氧预算。 鉴于有限的交换和可管理的规模，贝德福德盆地具有大型自然中生态系统的特征，因此时间序列可以详细检查物种形成变化以及氮和碘通量的过程。该时间序列将为 HQP 项目提供背景，该项目将涉及重复的短期实验操作，以测试和完善对化学和微生物介导的转化（例如硝化；碘酸盐还原）的理解和参数化。在这两个地点，时间序列为 HQP 的多学科团队提供了开展互补项目的环境。该研究将提供： (a) 利用全面的现场数据，测试自 1950 年代以来一直争论不休的关于春季浮游植物大量繁殖的各种假设； (b) 了解通过深度混合输送到深海的有机碳和氧对气候变化的敏感性； (c) 了解沿海海洋中氮和碘形态和通量的控制。