Atmospheric Transport of North African Dust‐Bearing Supermicron Freshwater Diatoms to South America: Implications for Iron Transport to the Equatorial North Atlantic Ocean
Atmospheric Transport of North African Dust‐Bearing Supermicron Freshwater Diatoms to South America: Implications for Iron Transport to the Equatorial North Atlantic Ocean
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DOI：
10.1029/2020gl090476
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发表时间：
2021-02
影响因子：
5.2
通讯作者：
A. Barkley;Nicole E. Olson;J. Prospero;Alexandre Gatineau;K. Panechou;N. Maynard;P. Blackwelder;S. China;A. Ault;C. Gaston
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文献类型：
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作者：
A. Barkley;Nicole E. Olson;J. Prospero;Alexandre Gatineau;K. Panechou;N. Maynard;P. Blackwelder;S. China;A. Ault;C. Gaston
赤道北大西洋(NAO)是一个营养有限的生态系统，依靠长距离输送的含铁(Fe)气溶胶的沉积来刺激初级生产力。利用显微镜，我们描述了北半球冬季和春季输送到北大西洋西部的超微米和超粗模非洲气溶胶的特征。我们检测到了三种颗粒类型，包括非洲尘埃、初级生物气溶胶颗粒和淡水硅藻(FDs)。FDS含有4%的铁，这是由于表面尘埃包裹体可能容易被化学处理和溶解所致。FDS通常比尘埃颗粒大，占直径在10至18μm之间的颗粒的38%。FD粒子的低密度、高表面积体积比和大纵横比表明了它们可以被携带到很远的高空的机制。这些相同的性质可能会增加FDs在地表水中的停留时间，从而增加铁的溶解时间，并对海洋生物地球化学循环产生潜在影响。
The equatorial North Atlantic Ocean (NAO) is a nutrient‐limited ecosystem that relies on the deposition of long‐range transported iron (Fe)‐containing aerosols to stimulate primary productivity. Using microscopy, we characterized supermicron and supercoarse mode African aerosols transported to the western NAO in boreal winter/spring. We detected three particle types including African dust, primary biological aerosol particles, and freshwater diatoms (FDs). FDs contained 4% Fe by weight due to surficial dust inclusions that may be susceptible to chemical processing and dissolution. FDs were typically larger than dust particles and comprised 38% of particles between 10 and 18 μm in diameter. The low density, high surface‐area‐to‐volume ratio, and large aspect ratios of FD particles suggest a mechanism by which they can be carried great distances aloft. These same properties likely increase the residence time of FDs in surface waters thereby increasing the time for Fe dissolution and their potential impact on marine biogeochemical cycles.