Collaborative Research (OSU, USC, RU): Continental Shelf Diagenesis II: The Importance of Increasing Oceanic Hypoxia to Coastal Iron Supply and the Ocean's Iron Isotope Composition

合作研究（俄勒冈州立大学、南加州大学、俄罗斯大学）：大陆架成岩作用 II：海洋缺氧加剧对沿海铁供应和海洋铁同位素组成的重要性

• 批准号: 1029739
• 负责人: Silke Severmann
• 金额: $ 27.52万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-15 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1029739&HistoricalAwards=false
• 关键词: Collaborative; Research; OSU; USC; RU

AbstractCoastal zone hypoxia (oxygen depletion) has both natural and, increasingly, anthropogenic dimensions that can lead to host of changes to the biogeochemical processes taking place on continental shelves. Continental shelf regions are well known to be important transition zones between terrestrial sources and the deep ocean. The objectives of this collaborative study are to determine the efflux rates of iron from coastal zone and continental shelf sediments to overlying water columns during the development of seasonal anoxia cycles. The underlying hypothesis being tested at selected study sites in the Gulf of Mexico, and on previously sampled materials from Peru and Namibia continental margins, is that the redox gradients occurring in these shelf sediments will deliver both increasing flux rates and with characteristically isotopically lighter Fe signatures as anoxia develops. If the extent of anoxia transitions to a sulfidic sediment regime, the benthic iron flux may decrease in a negative feedback loop due to solubility constraints, but with even lighter isotopic Fe escaping to the water column. A better understanding of the diagenetically delivered flux of iron, an essential micronutrient for phytoplankton growth, from sediments is sought to account for the global balance of ocean productivity under changing oceanic conditions. The ability of Fe-isotopic systematics to trace coastal benthic iron sources is a potentially transformative outcome of this research. The work will also strengthen the international collaboration between US, and German researchers, and provide an opportunity to develop these ideas with methodologies such as benthic chambers for bottom water sampling, as well as sediment pore fluids and core incubations, and water column isotopic studies. A range of educational and outreach activities will also be carried out.

摘要代码区缺氧（氧耗竭）具有天然和越来越多的人为维度，可以导致大陆架子上发生的生物地球化学过程的多种变化。众所周知，大陆架区域是陆地和深海之间的重要过渡区。这项合作研究的目标是确定沿海地区和大陆架沉积物的铁的外排速率在季节性缺氧周期发展过程中覆盖水柱。在墨西哥湾的选定研究地点以及先前从秘鲁和纳米比亚大陆边缘采样的材料上测试的基本假设是，这些货架沉积物中发生的氧化还原梯度既可以提供增加的通量速率，又可以带来增加的磁通速率，并且具有同性恋的特征性较轻的FE签名，因为Anoxia也会发育。如果缺氧向硫化沉积物状态过渡的程度，底栖铁通量可能会因溶解度限制而导致负反馈回路减少，但是更轻的同位素Fe逃到了水柱上。 寻求更好地了解铁的浮游铁的通量，这是浮游植物生长的必不可少的微量营养素，从沉积物中寻求考虑在不断变化的海洋条件下的全球海洋生产率平衡。 Fe-异位系统能够追踪沿海底栖铁源的能力是这项研究的潜在变革结果。这项工作还将加强我们与德国研究人员之间的国际合作，并提供了一个机会，可以使用诸如用于底部水采样的底栖动物室以及沉积物孔隙液和核心孵化以及水柱同位素研究来开发这些想法。 还将进行一系列教育和外展活动。