Chemical concentrations and fluxes from EPICA ice cores EDML and EDC

Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring in Antarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate of changes in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosol source. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes in the glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of the Southern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of the atmospheric dust concentration changes in Antarctica, while factor 5-10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmental conditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2-4 °C warmer temperatures recorded in Antarctica during the penultimate interglacial than today. 2-3 times higher sea salt fluxes found in both ice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and the distant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea ice formation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than in the Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea ice coverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka before present sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to the large distance of the sea ice salt source to our drill sites.

连续的海盐和矿物粉尘气溶胶记录已在两个EPICA（欧洲南极冰芯钻探项目，European Project for Ice Coring in Antarctica）深冰芯中开展研究。结合南极东部高原两侧的这些记录，不仅可以估算粉尘传输和排放强度的变化，还能识别海盐气溶胶源的区域差异。两个站点的矿物粉尘通量记录在过去15万年中显示出强烈的一致性，这与冰川期巴塔哥尼亚粉尘源的排放变化相关——南大洋（SO）大西洋扇区的粉尘通量比印度洋扇区高3倍。使用简单的概念性传输模型表明，传输仅能解释南极大气粉尘浓度变化的40%，而实际变化幅度达5-10倍。因此，南极冰川期粉尘通量剧烈变化的主要原因必然在于巴塔哥尼亚的环境变化。尽管倒数第二次间冰期南极的温度比现今高2-4°C，但巴塔哥尼亚的粉尘排放（进而其环境条件）在过去两次冰川期和间冰期分别表现出高度相似性。两个冰芯中冰川期的海盐通量比全新世高2-3倍，这难以与传输强度基本不变以及遥远的开阔海洋源相协调。假设海冰形成是海盐气溶胶的主要来源，且威德尔海（夏季）海冰的扩张范围显著大于南大洋印度洋扇区，则冰川期海盐气溶胶通量的大幅增加可得到合理解释。在倒数第二次间冰期，我们的海盐记录表明，南大洋印度洋和大西洋扇区的冬季海冰覆盖范围比全新世减少了50%。然而，在距今2万至8万年间，尽管温度波动显著，但海盐通量仅表现出非常微弱的千年尺度变化，这可能是由于海冰盐源与我们钻探站点的距离较远所致。