Identification, targeted extraction and source apportionment of magnetic micro- and nanoparticles in particulate matter

在我们以前的工作的基础上，人为和自然颗粒物（PM）在慕尼黑和周围地区在1999-2001年，我们提出了一个高分辨率的微磁和电子显微镜PM调查约25年后。我们建议开发一种独特的系统，使我们能够从尘埃中提取单个微米大小的磁性颗粒，并通过闪光量热法测量它们的居里温度。令人惊讶的是，在PM研究中很少进行磁性分析，因为它们相对容易，灵敏度和成本效益，再加上含铁颗粒可能对人类健康构成严重风险。例如，2022年3月，大量撒哈拉沙尘吹进了慕尼黑，使天空变黄，覆盖了所有表面。我们对尘埃的分析显示出令人惊讶的高磁化率;居里温度测量在770°C时产生了明显的信号，表明存在金属铁。这就提出了一些重要的问题：铁从哪里来，它是如何运输的，在氧化成磁铁矿，然后是赤铁矿或磁赤铁矿之前，它能在金属相中持续多久？在慕尼黑的地方一级，我们打算解决以下问题的特点和发生的磁性PM：1）如何比例和组成的磁性PM组件之间的变化1999-2001年和2023-2025年？2)哪些来源在发射磁性粒子？3)把磁性粒子带到慕尼黑的交通路线是什么？为了识别和表征尘埃中的磁性成分，我们希望进一步开发所谓的磁阵-一种由四个电磁铁包围的高分辨率光学显微镜。我们打算用一个非常精确的微量吸管提取器来补充磁场。该集成将使我们能够有效地选择磁性颗粒，并自动将它们放置在SEM样品架上用于后续显微镜或用于闪光量热法的网格上。散装样品将在现有设备上进行一系列磁性测量，以进一步表征其磁性，以及X射线衍射和穆斯堡尔光谱等非磁性技术。本文的工作将是博士论文的基础。将在慕尼黑地区的关键地点定期采集样本，这些地点是专门为区分人为来源和自然来源而选择的。此外，我们还将与西班牙经验丰富的合作伙伴（Manuel Calvo Rathert，Uni.布尔戈斯;爱德华多科隆博，魔术望远镜，拉帕尔马）和意大利（法比奥弗洛林多，大学。罗马）谁将提供样品。对来自意大利、西班牙和加那利群岛的灰尘样本进行进一步分析，应有助于回答有关金属铁来源的关键问题，众所周知，金属铁对人类健康极为有害。与奥地利Hoher Sonnblick天文台的合作将使我们能够分析多年的PM记录。

Building on our previous work on anthropogenic and natural particulate matter (PM) in and around Munich during 1999-2001, we propose a high resolution micro-magnetic and electron microscopic investigation of PM some 25 years later. We propose to develop a unique system that will allow us to extract individual micron-sized magnetic particles from dust and measure their Curie temperatures via flash calorimetry. Magnetic analyses are surprisingly rarely made in PM studies, given their comparative ease, sensitivity and cost effectiveness, combined with the fact that iron bearing particles can be a serious risk to human health. For example, in March 2022, an enormous volume of Saharan dust blew into Munich that turned the sky yellow and blanketed all surfaces. Our analyses of the dust showed surprisingly high magnetizations; Curie temperature measurements yielded a distinct signal at 770°C, signifying the presence of metallic iron. This raises the important questions: where did the iron come from, how was it transported and how long can it last in the metal phase, before oxidizing to magnetite and then hematite or maghemite? On a local level in Munich, we intend to address the following questions regarding the characteristics and occurrence of the magnetic PM: 1) How did the proportion and composition of the magnetic PM component change between 1999-2001 and 2023-2025? 2) Which sources are emitting the magnetic particles? 3) What are the transportation routes that bring magnetic particles to Munich? To identify and characterize the magnetic components in the dust, we want to further develop the so called Magnetodrome - a high resolution optical microscope surrounded by four electromagnets. We intend to compliment the Magnetodrome with an extremely precise micro-pipette extractor. The ensemble will allow us to efficiently select magnetic particles and automatically place them on SEM sample holders for subsequent microscopy or onto grids for flash calorimetry. Bulk samples will be further subjected to a suit of magnetic measurements on existing equipment to further characterize their magnetic properties, as well as non-magnetic techniques like X-ray diffraction and Mößbauer-spectroscopy. The work herein will be the basis for a doctoral thesis. Samples will be collected at regular intervals at key places in the Munich area chosen specifically to unravel anthropogenic from natural sources. Moreover, we will cooperate with experienced partners in Spain (Manuel Calvo Rathert, Uni. Burgos; Eduardo Colombo, MAGIC Telescope, La Palma) and Italy (Fabio Florindo, Uni. Rome) who will provide samples. Further analyses of dust samples from Italy, Spain and the Canary Islands should help to answer the key questions concerning the source of metallic iron, which is known to be extremely hazardous to human health. A cooperation with the Hoher Sonnblick observatory in Austria will enable us to analyze years of PM recordings.