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，它通过各种外部来源进入热带北大西洋，包括河流径流、大气粉尘和大陆边缘，但大气粉尘的沉积是该地区铁元素的主要来源。然而，尽管大气尘埃输送的大小和路径有季节性波动，但表面营养物质的持续消耗和海洋颜色的中等偏高表明，其他来源正在向该地区提供铁。伍兹霍尔海洋研究所（Woods Hole Oceanographic Institute）的科学家们计划验证一个假设，即非洲西北部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。为了验证这一假设，主要研究人员将在冬季访问佛得角附近的新热带东北大西洋时间序列观测站（TENATSO）时使用一种新的测量组合（即同步加速器x射线分析颗粒铁，镭同位素，234剖面），该观测站位于热带大西洋东部，位于毛里塔尼亚沿海上升流下游约850公里处。和麻省理工学院的一位科学家一起研究了从毛里塔尼亚海岸到特纳索的夏季跨大陆架样带。预计跨大陆架样带和拟议的测量将使他们能够确定横向运输与粉尘输入和地下再矿化作为表层海洋铁源的重要性。至于更广泛的影响，这项研究将提供新的见解，了解生物可利用铁的横向来源对热带北大西洋的重要性。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，并通过在国家海洋环境研究所的报告传播研究结果。

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.