Supplementary information files for Increased North Atlantic dust deposition linked to Holocene Icelandic glacier fluctuations

Supplementary files for article Increased North Atlantic dust deposition linked to Holocene Icelandic glacier fluctuationsMineral dust concentrations are coupled to climate over glacial-interglacial cycles with increased dust deposition occurring during major cold phases over the last ~100 ka. Holocene records suggest considerable spatial and temporal variability in the magnitude, frequency and timing of dust peaks that reflects regional or local drivers of dust emissions and transport. Here, we present stratigraphical, geochemical and isotopic evidence for dust deposition from two high-resolution peat sequences 200 km apart in northern Scotland spanning the last c. 8200 years. εNd isotope data suggest the dominant minerogenic dust source switches between a low latitude (likely Saharan) and a high latitude, Icelandic source. Marked peaks in increased minerogenic dust deposition at: c. 5.4–5.1, 4.0–3.9, 2.8–2.6, 1.0 and 0.3 ka BP occur against a backdrop of low dust deposition during the mid-Holocene (c. 5.0–4.0 ka BP) and increased background levels of dust during the neoglacial period (<4.0 ka BP). These dust peaks coincide with periods of glacial advance in Iceland and heightened storminess in the North Atlantic. Isotope data for additional dust peaks at c. 1.0 and 0.7 ka BP and the last ~50 years suggest these reflect increased dust from the Sahara associated with aridity and land-use change in North Africa during the Late-Holocene, and modern anthropogenic sources. This work highlights the complexity of Holocene records of dust deposition in the North Atlantic and emphasises the role of dynamic sub-Polar glaciers and their meltwater systems as a significant dust source.

《北大西洋粉尘沉积增强与全新世冰岛冰川波动相关》论文补充材料。在冰期-间冰期旋回中，矿物粉尘浓度与气候紧密耦合，在过去约10万年的主要冷期内粉尘沉积量会出现升高。全新世粉尘记录显示，粉尘峰值的强度、出现频次与时间存在显著的时空异质性，这反映了粉尘排放与传输的区域或局地驱动因素。本研究针对苏格兰北部两处间距200公里、时间跨度约8200年的高分辨率泥炭序列，提供了粉尘沉积的地层学、地球化学与同位素证据。εNd同位素（εNd isotope）数据显示，研究区主要的矿质粉尘源区在低纬度地区（大概率为撒哈拉地区）与高纬度冰岛源区之间切换。矿质粉尘沉积显著升高的峰值出现在约5.4~5.1 ka BP、4.0~3.9 ka BP、2.8~2.6 ka BP、1.0 ka BP与0.3 ka BP；而全新世中期（约5.0~4.0 ka BP）粉尘沉积量处于较低水平，新冰期（<4.0 ka BP）的背景粉尘浓度则有所升高。这些粉尘峰值与冰岛冰川前进时期以及北大西洋风暴活动增强的时段相吻合。针对约1.0 ka BP、0.7 ka BP以及过去约50年出现的额外粉尘峰值的同位素数据显示，这些峰值分别对应全新世晚期北非干旱化与土地利用变化引发的撒哈拉粉尘增加，以及现代人为源粉尘。本研究揭示了北大西洋全新世粉尘沉积记录的复杂性，并强调了动态亚极地带冰川及其融水系统作为重要粉尘源区的作用。