Here we present an environmental magnetic study of atmospheric deposition collected by a multi-site network in Spain that covers fourteen locations representative of urban, industrial, agricultural, and natural environments across southwestern Europe. We have combined magnetic methods with scanning electron microscopy and geochemical data to characterize the magnetic mineral assemblages of particulate matter across different types of sites and phenomenological scenarios, and to unravel their environmental significance in terms of the most important anthropogenic and natural components of atmospheric deposition. Our results enable identification of two magnetite/maghemite components of anthropogenic origin, derived mostly from vehicular traffic, plus a hematite component associated with a baseline supply of north African dust, in all the studied sites regardless of their type. The ubiquitous presence of anthropogenic magnetite/maghemite particles in pristine natural environments, albeit in lower concentrations, point to their arrival from neighbouring urban areas through atmospheric mixing processes. Samples including particulate matter deposited during distinctively intense periods of north African dust supply are characterized by a fourth component, represented also by coarser-grained hematite, that is likely derived from a different source area within the Sahara Desert. The concomitant increase observed in these cases in the amounts of magnetite/maghemite particles suggests strongly that part of the magnetite/maghemite load attributed to anthropogenic sources for the rest of the phenomenological scenarios is aeolian in origin. This seems to explain the overall moderate correlation observed between magnetite/maghemite contents and proxies for vehicular traffic, and demonstrates the need for caution when interpreting environmental magnetic proxies for magnetite/maghemite abundances in terms of anthropogenic loads. This is especially the case in southern European cities where a steady supply of north African dust occurs throughout most of the year. Our results show a good correlation between hematite abundances and geochemical proxies for north African dust, which collectively delineate broad maxima during the summer and large peaks during distinctive dust breakouts. Thus, environmental magnetic proxies of hematite abundances can be used to monitor the contribution of natural sources to atmospheric deposition.

在这里，我们展示了由西班牙多站点网络收集的大气沉降环境磁学研究，该网络涵盖了代表欧洲西南部城市、工业、农业和自然环境的 14 个地点。我们将磁学方法与扫描电子显微镜和地球化学数据相结合，以表征不同类型地点和现象学情景中颗粒物质的磁性矿物组合，并根据大气沉积的最重要的人为和自然成分阐明它们的环境意义。我们的结果能够识别出两种人为来源的磁铁矿/磁赤铁矿成分，主要来自车辆交通，以及与北非粉尘的基线供应相关的赤铁矿成分，在所有研究的站点中，无论其类型如何。人为磁铁矿/磁赤铁矿颗粒在原始自然环境中无处不在，尽管浓度较低，但表明它们是通过大气混合过程从邻近城市地区到达的。样品包括在北非粉尘供应特别强烈的时期沉积的颗粒物质，其特征在于第四种成分，也以粗粒赤铁矿为代表，可能来自撒哈拉沙漠内的不同源区。在这些情况下观察到的磁铁矿/磁赤铁矿颗粒量的伴随增加强烈表明，在其余的现象学情景中，部分磁铁矿/磁赤铁矿负荷归因于人为来源是风成起源的。这似乎解释了在磁铁矿/磁赤铁矿含量与车辆交通代理之间观察到的总体中度相关性，并表明在从人为负荷方面解释磁铁矿/磁赤铁矿丰度的环境磁性代理时需要谨慎。在南欧城市尤其如此，那里全年大部分时间都在稳定供应北非粉尘。我们的结果显示赤铁矿丰度与北非尘埃的地球化学指标之间存在良好的相关性，它们共同描绘了夏季的宽阔最大值和独特的尘埃爆发期间的大峰。因此，赤铁矿丰度的环境磁性替代物可用于监测自然资源对大气沉积的贡献。