Oxford Resilient Buildings and Landscapes Laboratory (OxRBL), School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK.
Marine Isotope Geochemistry, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg, Germany.
Sci Total Environ. 2021 Mar 10;759:143916. doi: 10.1016/j.scitotenv.2020.143916. Epub 2020 Dec 3.
Black crusts on historic buildings are mainly known for their aesthetic and deteriorative impacts, yet they also can advance air pollution research. Past air pollutants accumulate in distinct layers of weathering crusts. Recent studies have used these crusts to reconstruct pollution to improve our understanding of its effects on stone-built heritage. However, the majority of the studies provide only coarse resolution reconstruction of pollution, able to distinguish between 'inner = old' and 'outer = modern' crust layers. In contrast, very few studies have linked distinct periods of exposure to pollution variations in the composition of these crusts. Here we address this research gap by developing a finer-scale resolution pollution record. Our study explored the unique configuration of limestone sculptures in central Oxford, which have been exposed over the last 350 years to three different periods of atmospheric pollution; the early Industrial Revolution, the Victorian period and the 20th century. When the first two generations of sculptures were moved to less polluted areas, their 'pollution clocks' were stopped. Here we discuss the potential of investigating the 'pollution clock' recorded in the geochemical makeup of each sculpture generation's weathering crust layers. We found the analysed crusts record clear changes related to the evolution of modes of transport and industrial and technological development in Oxford. Higher levels of Arsenic (As), Selenium (Se) are linked to pollution from coal burning during Victorian times and Lead (Pb) indicated leaded petrol use in modern times. Our work shows that stone-built heritage with a known history of air pollution exposure allows improving the pollution reconstruction resolution of these weathering crusts. The results provide the basis for calibrating long-term geochemical archives. This approach may be used to reconstruct past air quality and has the potential to inform stone weathering research and conservation, in addition to improving the reconstruction of historical pollution.
历史建筑上的黑色外壳主要因其美观和恶化影响而为人所知，但它们也可以推进空气污染研究。过去的空气污染物在风化外壳的不同层中积累。最近的研究利用这些外壳来重建污染，以提高我们对其对石质建筑遗产影响的理解。然而，大多数研究仅对污染进行粗略的分辨率重建，能够区分“内部=旧”和“外部=现代”外壳层。相比之下，很少有研究将不同时期的暴露与这些外壳中污染成分的变化联系起来。在这里，我们通过开发更精细的分辨率污染记录来解决这一研究差距。我们的研究探索了牛津市中心石灰岩雕塑的独特配置，这些雕塑在过去 350 年中经历了三个不同的大气污染时期；早期工业革命、维多利亚时期和 20 世纪。当前两代雕塑被移到污染较少的地区时，它们的“污染时钟”就停止了。在这里，我们讨论了调查每一代雕塑风化外壳层中记录的“污染时钟”的潜在可能性。我们发现，分析的外壳记录清楚地反映了与牛津运输方式演变、工业和技术发展相关的变化。砷 (As) 和硒 (Se) 的含量较高与维多利亚时代煤炭燃烧造成的污染有关，而铅 (Pb) 则表明现代使用含铅汽油。我们的工作表明，具有已知空气污染暴露史的石质建筑遗产可以提高这些风化外壳的污染重建分辨率。研究结果为校准长期地球化学档案提供了基础。这种方法可用于重建过去的空气质量，并有可能指导石质风化研究和保护，以及改善历史污染的重建。
