Physical Weathering Intensity Controls Bioavailable Primary Iron(II) Silicate Content in Major Global Dust Sources
Physical Weathering Intensity Controls Bioavailable Primary Iron(II) Silicate Content in Major Global Dust Sources
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DOI：
10.1029/2019gl084180
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发表时间：
2019-10
影响因子：
5.2
通讯作者：
E. Shoenfelt;G. Winckler;A. Annett;K. Hendry;B. Bostick
中科院分区：
文献类型：
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作者：
E. Shoenfelt;G. Winckler;A. Annett;K. Hendry;B. Bostick
到达海洋的铁（Fe）的形态，例如在风吹尘和沿海沉积物中，影响其对浮游植物的生物利用度及其对大气二氧化碳（CO2）和气候的影响。对于到达南大洋的尘埃，与化学风化的富含Fe（III）的物质相比，从基岩物理风化的初级Fe（II）硅酸盐具有高度的生物可利用性，这表明尘埃源区的风化影响了生物可利用的Fe供应。然而，这种现象还没有在其他重要的陆地铁源，其中风化制度和源地质不同的研究。在这里，我们使用海洋沉积物岩心的Fe X射线吸收光谱来表明，受高度物理风化影响的全球主要灰尘和沉积物来源含有丰富的原生矿物质，因此被忽视为全球高度生物可利用的Fe来源。因此，重要的是要考虑物理与化学风化的铁施肥和生物CO2循环的作用。
The speciation of iron (Fe) reaching the ocean, for instance in wind‐blown dust and coastal sediments, impacts its bioavailability to phytoplankton and its impact on atmospheric carbon dioxide (CO2) and climate. For dust reaching the Southern Ocean, primary Fe(II) silicates that are physically weathered from bedrock are highly bioavailable compared to more chemically weathered, Fe(III)‐rich species, suggesting that weathering in dust source regions impacts the bioavailable Fe supply. However, this phenomenon has not been studied in other important terrestrial Fe sources, where weathering regimes and source geology vary. Here, we use Fe X‐ray absorption spectroscopy on marine sediment cores to show that major global dust and sediment sources impacted by high physical weathering contain abundant primary minerals and thus are overlooked as a source of highly bioavailable Fe globally. Thus, it is important to consider the role of physical versus chemical weathering in Fe fertilization and biotic CO2 cycling.