Physico-chemical properties of Saharan dust samples deposited across Europe in March 2022 and collected through a participatory approach

A particularly long and dense episode of airborne dust transport crossed Spain, France and part of Europe from 15 to 18 March 2022. This episode led to significant dust deposits on cars, roofs, etc., which may have caused surprise or concern among the general public. Based on association reports, several media published articles stating that this dust contained an artificial radionuclide, cesium-137 (137Cs), the source of which was attributed to the French nuclear tests conducted in the Sahara early in the 1960s. In order to provide a solid and representative scientific basis for a better characterisation of this dust and its radionuclide content, a participatory call for the collection of about ten grams of dust in different sites in France and Europe was launched on 17 March 2022 on the social network Twitter by Olivier Evrard. It was then relayed by Germán Orizaola, generating numerous reactions and the collection of several dozen samples in France, Spain and other neighbouring countries in Europe. The current dataset provides general information about the location/time of sample collection (n=110 samples) and data about the content of dust samples in cesium-137 (137Cs), an artificial radionuclide emitted by nuclear atmospheric tests and accidents (Evrard et al., 2020). Samples (2-80g) were analysed using the ultra-low background Germanium HyperPure gamma spectrometry detectors of LSCE installed in the underground facilities at both University Paris-Saclay (Gif-sur-Yvette) and Modane (Underground Lab of Modane, France). Filters were analysed for 80,000 to 200,000 s to obtain sufficient counting statistics (for the detection of the 137Cs peak at 662 keV). All results were expressed in Bq kg−1 with activities decay-corrected to the sampling date. Counting efficiencies and reliability were conducted using certified International Atomic Energy Agency (IAEA) standards (IAEA-444, 135, 375, RGU-1 and RGTh-1) prepared in the same containers as the samples. Additional data regarding other physico-chemical properties analysed in these dust samples has been added in June 2024.2022年3月15日至18日，一场持续时间长、强度极高的悬浮沙尘输送事件横跨西班牙、法国及欧洲部分区域。此次事件导致车辆、屋顶等表面出现大量沙尘沉积，引发了公众的诧异与担忧。据相关报道，多家媒体发文称该沙尘中检出人工放射性核素铯-137（cesium-137, ¹³⁷Cs），其来源被归因于20世纪60年代初法国在撒哈拉地区开展的核试验。 为给该沙尘及其放射性核素成分的精准表征提供坚实且具代表性的科学依据，奥利维耶·埃夫拉尔（Olivier Evrard）于2022年3月17日通过社交平台推特（Twitter）发起公众征集活动，呼吁在法国及欧洲各地收集约10克沙尘样本。该活动随后被赫尔曼·奥里佐拉（Germán Orizaola）转发，引发大量响应，最终在法国、西班牙及欧洲其他周边国家收集到数十份样本。 本数据集包含110份沙尘样本的采集位置与时间等基础信息，以及各样本中铯-137（¹³⁷Cs）的含量数据。铯-137是一种由大气核试验与核事故释放的人工放射性核素（Evrard等，2020）。所有样本（重量2~80克）均采用法国气候与环境科学实验室（Laboratoire des Sciences du Climat et de l'Environnement, LSCE）的超低本底高纯锗γ能谱探测器进行分析，这些探测器分别部署于巴黎萨克雷大学（吉夫苏尔伊韦特校区）以及法国莫丹地下实验室的地下设施中。单份样本的分析时长为80000~200000秒，以获得足够的计数统计量，确保662 keV处的¹³⁷Cs特征峰可被有效检出。所有结果均以贝可每千克（Bq·kg⁻¹）为单位，并将放射性活度校正至样本采集当日的衰变值。计数效率与分析可靠性通过国际原子能机构（International Atomic Energy Agency, IAEA）认证的标准物质进行验证，所用标准物质包括IAEA-444、135、375、RGU-1及RGTh-1，且均采用与样本一致的容器制备。 2024年6月，本数据集新增了这批沙尘样本中其他理化性质的分析数据。