Asian dust delivers highly reactive iron (Fe_HR) to the Pacific Ocean, affecting marine biogeochemical cycles and Earth's climate. Tracing the source of dust deposited in the Pacific is vital for assessing global nutrient cycles but poses challenges. This work applies the (²³⁴U/²³⁸U) activity ratio to determine the pre-deposition time and provenance of dust in North Pacific Ocean sediments (Ocean Drilling Program site 1209B). Results indicate a consistent dust pre-deposition time (134 ± 10 ka) over the past 300,000 years, except during Marine Isotope Stage 7 when volcanic ash input shortened it to 31 ± 19 ka. Comparing the dust pre-deposition times to those of the potential source deserts, we identify the dust transported to the North Pacific Ocean was primarily from the Taklamakan Desert, which contains higher Fe_HR content than other deserts. This finding enhances our understanding of soluble Fe supplied to the oceans, especially in dust circulation models.

中文翻译：

---

铀同位素对亚洲沙尘预沉积到北太平洋的时间的限制：对来源和铁供应的影响

亚洲尘埃向太平洋输送高活性铁 (Fe _HR )，影响海洋生物地球化学循环和地球气候。追踪太平洋沉积灰尘的来源对于评估全球营养循环至关重要，但也带来了挑战。这项工作应用 ( ²³⁴ U/ ²³⁸ U) 活度比来确定北太平洋沉积物中灰尘的预沉积时间和来源（海洋钻探计划站点 1209B）。结果表明，过去 30 万年中灰尘预沉积时间一致（134 ± 10 ka），但在海洋同位素第 7 阶段除外，火山灰输入将其缩短至 31 ± 19 ka。将沙尘预沉积时间与潜在源沙漠的沙尘预沉积时间进行比较，我们发现输送到北太平洋的沙尘主要来自塔克拉玛干沙漠，该沙漠的铁_HR含量高于其他沙漠。这一发现增强了我们对海洋中可溶性铁的理解，特别是在灰尘循环模型中。