The subarctic Pacific Ocean and Bering Sea comprise the second‐largest high nitrate, low chlorophyll region in the world, where primary production is limited by the availability of iron (Fe). To estimate the potential impact of different terrestrial aerosol Fe sources on marine ecosystems, we performed a suite of laboratory assessments following established protocols, including: (1) leaching with Milli‐Q water, (2) sequential extractions, (3) complete acid digestions, (4) X‐ray diffraction, and (5) grain size analysis. Measurements were performed on 20 fine‐grained (<5 μm) glacier‐derived sediments from Alaska and the Yukon, two fresh, never‐wetted volcanic ashes (Redoubt 2009 and Pavlof 2016), and six weathered ashes (Redoubt and Augustine) which span the past ∼8,700 years. We compared results to published data on Asian desert‐derived sediments, finding that the glacier‐derived sediments have five times higher easily reducible Fe (median 2.3 ± 0.6 wt.%) than desert‐derived samples (0.49 ± 0.1 wt.%) and fourteen times higher easily reducible Fe than fresh ash (0.16 ± 0.1 wt.%). In addition, fractional Fe solubility was higher in glacial sediment (median cumulative 0.31 ± 0.11% Fe_S) than volcanic ash (0.04 ± 0.02% Fe_S). Glacial sediments contained higher concentrations of other bioactive metals including Co, Ni, Cu, Zn, Mo, Cd, and Pb. Results suggest that glacier‐derived dust may provide the subarctic Pacific with more bioavailable iron per unit mass than either volcanic ash or Asian desert‐derived dust.

中文翻译：

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冰尘的铁肥潜力超过了火山灰和沙漠尘

亚北极太平洋和白令海是世界上第二大高硝酸盐，低叶绿素区域，那里的主要生产受到铁（Fe）的供应的限制。为了估算不同陆地气溶胶铁源对海洋生态系统的潜在影响，我们按照既定规程进行了一系列实验室评估，包括：（1）用Milli-Q水浸出，（2）连续萃取，（3）完全酸消化，（4）X射线衍射和（5）粒度分析。对来自阿拉斯加和育空地区的20个细粒度（<5μm）冰川沉积物，两个未润湿的新鲜湿火山灰（Redoubt 2009和Pavlof 2016）以及六个跨度的风化灰（Redoubt和Augustine）进行了测量。过去约8,700年。我们将结果与关于亚洲沙漠源性沉积物的公开数据进行了比较，发现冰川源性沉积物的易还原铁（中值2.3±0.6 wt。％）比沙漠源性样品（0.49±0.1 wt。％）高五倍。易还原铁的含量是新鲜灰分（0.16±0.1重量％）的14倍。此外，在冰川沉积物中铁的​​溶解度分数较高（中值累积铁为0.31±0.11％_S）比火山灰（0.04±0.02％Fe _S）。冰川沉积物中含有较高浓度的其他生物活性金属，包括Co，Ni，Cu，Zn，Mo，Cd和Pb。结果表明，与火山灰或亚洲沙漠源尘埃相比，冰川源尘埃可以为北极亚太平洋提供每单位质量更多的生物可利用铁。