Iron (Fe) is a key element in the Earth climate system, as it can enhance marine primary productivity in the high-nutrient low-chlorophyll (HNLC) regions where, despite a high concentration of major nutrients, chlorophyll production is low due to iron limitation. Eolian mineral dust represents one of the main Fe sources to the oceans; thus, quantifying its variability over the last glacial cycle is crucial to evaluate its role in strengthening the biological carbon pump. Polar ice cores, which preserve detailed climate records in their stratigraphy, provide a sensitive and continuous archive for reconstructing past eolian Fe fluxes. Here, we show the Northern Hemisphere Fe record retrieved from the NEEM ice core (Greenland), which offers a unique opportunity to reconstruct the past Fe fluxes in a portion of the Arctic over the last 108 kyr. Holocene Fe fluxes (0.042–11.7 ka, 0.5 mg m⁻² yr⁻¹) at the NEEM site were 4 times lower than the average recorded over the last glacial period (11.7–108 ka, 2.0 mg m⁻² yr⁻¹), whereas they were greater during the Last Glacial Maximum (LGM; 14.5–26.5 ka, 3.6 mg m⁻² yr⁻¹) and Marine Isotope Stage 4 (MIS 4; 60–71 ka, 5.8 mg m⁻² yr⁻¹). Comparing the NEEM Fe record with paleoceanographic records retrieved from the HNLC North Pacific, we found that the coldest periods, characterized by the highest Fe fluxes, were distinguished by low marine primary productivity in the subarctic Pacific Ocean, likely due to the greater sea ice extent and the absence of major nutrients upwelling. This supports the hypothesis that Fe fertilization during colder and dustier periods (i.e., LGM and MIS 4) was more effective in other regions, such as the midlatitude North Pacific, where a closer relationship between marine productivity and the NEEM Fe fluxes was observed.

中文翻译：

---

冰河北太平洋的大气铁供应和海洋生产力

铁（Fe）是地球气候系统中的关键元素，因为它可以提高高营养低叶绿素（HNLC）地区的海洋初级生产力，尽管主要营养素含量很高，但由于铁而导致叶绿素产量低局限性。风尘矿物粉尘是海洋中铁的主要来源之一。因此，量化其在最后一次冰川循环中的变异性对于评估其在增强生物碳泵中的作用至关重要。极地冰芯在地层中保留了详细的气候记录，为重建过去的风铁流提供了灵敏而连续的档案。在这里，我们显示了从NEEM冰芯（格陵兰岛）取回的北半球铁记录，这为重建过去108年以来北极部分地区过去的铁通量提供了独特的机会。NEEM站点的⁻²  yr ^-1）比上一个冰川期（11.7–108 ka，2.0 mg m ⁻²  yr ^-1）的平均记录低4倍，而在上一个冰川期（LGM）更大。 ; 14.5–26.5 ka，3.6 mg m ^-2  yr ^-1）和海洋同位素阶段4（MIS 4; 60–71 ka，5.8 mg m ^-2  yr ^-1）。将NEEM Fe记录与从HNLC北太平洋获取的古海洋学记录进行比较，我们发现，以铁通量最高为特征的最冷期，其特征是北极洋中海洋初级生产力较低，这可能是由于海冰范围更大并且没有主要营养物质上升。这支持以下假设：在较冷和多尘的时期（例如LGM和MIS 4），在其他地区（例如北太平洋中纬度地区）观察到的海洋生产力与NEEM铁通量之间的关系更为紧密，铁肥的施用更为有效。