Sources of Iron to the Eastern Tropical Atlantic: Does the Continental Margin Supplement Saharan Dust?

铁是海洋初级生产过程中必需的微量营养素，通过各种外部来源进入热带北大西洋，包括河流径流、大气尘埃和大陆边缘，但大气尘埃的沉积是该元素进入该区域的主要来源。 然而，尽管大气尘埃输送的幅度和路径存在季节性波动，但表面营养物质的持续消耗和适度高的海洋颜色表明其他来源正在为该地区提供铁。 来自伍兹霍尔海洋研究所的科学家们计划验证一个假设，即西北非洲的大陆边缘为热带大西洋东部提供了大量的地下铁供应，补充了尘埃。 为了检验这一假设，主要研究人员将使用一种新的测量组合（即，在冬季访问佛得角附近新的热带东大西洋时间序列观测站（TENATSO）期间，与来自马萨诸塞州理工学院的一名科学家一道，对颗粒铁、镭同位素、234 Th剖面进行了同步加速器X射线分析（TENATSO），该观测站位于热带大西洋东部，在南大洋沿岸上升流下游约850公里处，并在夏季访问了从南大洋海岸到TENATSO的跨大陆架断面。 预计跨大陆架断面和拟议的测量将使他们能够确定横向迁移与灰尘输入和地下矿化作为表层海洋铁源的重要性。 至于更广泛的影响，这项研究将为生物可利用铁的横向来源对热带北大西洋的重要性提供新的见解。 伍兹霍尔海洋研究所的科学家计划与佛得角群岛的科学家合作，培训研究人员如何测定钍、镭和铁，并通过在国家渔业发展研究所的演讲传播研究结果。

Iron, a necessary micronutrient used during primary production in the ocean, enters the tropical North Atlantic through various external sources including river runoff, atmospheric dust, and continental margins, but deposition of atmospheric dust is the primary source of this element to this region. However, despite seasonal fluctuation in the magnitude and path of atmospheric dust delivery, persistent depletion of surface nutrients and moderately high ocean color indicates that other source(s) are providing iron to this area. Scientists from Woods Hole Oceanographic Institute plan to test the hypothesis that the continental margin of northwest Africa provides a significant subsurface supply of iron to the eastern tropical Atlantic that supplements dust. To test this hypothesis, the principal investigators would use a novel combination of measurements (i.e., synchrotron x-ray analysis of particulate iron, radium isotopes, 234Th profiles) during a wintertime visit to the new Tropical Eastern North Atlantic Time-Series Observatory (TENATSO) near Cape Verde, located in the eastern tropical Atlantic about 850 km downstream of Mauritanian coastal upwelling, and a summertime cross-shelf transect from the Mauritanian coast to TENATSO with a scientist from Massachusetts Institute of Technology. It is anticipated that the cross shelf transect and the proposed measurements would allow them to determine the importance of lateral transport versus dust inputs and subsurface remineralization as iron sources to the surface ocean. As regards broader impacts, the research would provide new insight into the importance of lateral sources of bioavailable iron to the tropical North Atlantic. Scientists from Woods Hole Oceanographic Institution plan to collaborate with those in the Cape Verde Islands, train the researchers in how to determine thorium, radium, and iron, and disseminate results from the study via presentations at the Instituto National de Desenvolvimento das Pescas.