Phytoplankton Organic Carbon and Sulfur Cycling at the Marginal Ice Edge Zone

边缘冰缘区浮游植物有机碳和硫循环

• 批准号: 9200436
• 负责人: Maria Vernet
• 金额: $ 31.87万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-03-15 至 1996-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9200436&HistoricalAwards=false
• 关键词: Phytoplankton; Organic; Carbon; Sulfur; Cycling

Arctic phytoplankton may act as a sink for carbon dioxide (CO2) and a major producer of dimethylsulfide (DMS). Maximum effects are expected in the marginal ice zone where phytoplankton blooms extend from May to September as the ice recedes northwards. These productive waters can cover more than half the area of arctic shelf seas, such as the Barents Sea, in any one growth period. One of the main components of the phytoplankton at the marginal ice zone is Phaeocystis pouchetii which, in its colonial form, is a high producer of DMS. This species is known to excrete a high proportion of newly fixed carbon as high molecular weight polymers in order to form the colony. Later, it sinks in mass in the latter stages of the bloom when nitrate becomes limiting. Diatoms, such as Thalassiosira gravida, may dominate the bloom at the ice edge late in the summer and may also precede the P. pouchetii bloom in early spring (i.e. Chaetoceros socialis). The different patterns of dissolved organic carbon formation and cell sedimentation between P. pouchetii and diatoms need to be included in productivity models for an understanding of the production and sink of CO2 and DMS in arctic shelf areas. The objectives of this field and laboratory study, in collaboration with Norwegian scientists, are to: (1) to determine the quantitative differences between P. pouchetii and diatoms blooms in the ice edge with respect to primary production, proportion of carbon fixed that is extracellular, DMS production, and sedimentation of particulate carbon and sulfur to depth: (2) to determine which are the main environmental variables that favor each type of bloom using a 10-year time series from the Barents Sea; and (3) to estimate a 10-year time series of DMS production and CO2 uptake by combining the existing time series with carbon and sulfur budgets of the ice edge blooms. This research will provide a first approximation to the seasonal and interannual variability of the phytoplankton contribution to the carbon and sulfur cycle during the ice edge bloom in arctic shelf areas.

北极浮游植物可以作为二氧化碳（CO2）的汇和二甲基硫化物（DMS）的主要生产者。预计影响最大的是边缘冰带，那里的浮游植物从5月持续到9月，海冰向北消退。在任何一个生长期，这些富有生产力的水域可以覆盖北极大陆架海洋（如巴伦支海）一半以上的面积。边缘冰带浮游植物的主要组成部分之一是褐囊藻（Phaeocystis pouchetii），在其殖民地形态下，是DMS的高生产者。已知该物种排泄高比例的新固定碳作为高分子量聚合物，以形成菌落。之后，在开花的后期，当硝酸盐变得有限时，它会大量下沉。硅藻，如海带藻（Thalassiosira gravida），可能在夏末主导冰边的开花，也可能先于P. pouchetii在早春的开花（即Chaetoceros socialis）。为了更好地理解北极陆架地区二氧化碳和DMS的产生和吸收，需要将P. pouchetii和硅藻之间不同的溶解有机碳形成和细胞沉积模式纳入生产力模型。与挪威科学家合作进行的这一实地和实验室研究的目标是：(1)在初级产量、细胞外固定碳的比例、DMS产量以及颗粒碳和硫向深度的沉降方面，确定P. pouchetii和冰边硅藻华之间的定量差异；(2)利用巴伦支海的10年时间序列，确定有利于每种水华类型的主要环境变量；(3)将现有时间序列与冰边华的碳和硫收支相结合，估算10年DMS生产和CO2吸收的时间序列。这项研究将为北极陆架地区冰缘水华期间浮游植物对碳和硫循环贡献的季节性和年际变化提供第一个近似。