Abstract

Daily fine (PM_2.5) and coarse (PM_10-2.5) particle matter samples collected at Parque O’Higgins station in downtown Santiago de Chile have been studied to find the trends in concentration from 1998 to 2018. Elemental concentration was obtained using X-ray fluorescence. Regression models from previous studies indicate that the PM_2.5 and PM_10-2.5 fractions have had a continuous decrease since 1988 mostly due to several policy control measures carried out over several decades. PM_2.5 has decreased from 68.3 in 1988 to 27.6 μg/m³ in 2018 (60.4%). However, if only the last 8 years are considered (2011 – 2018), a leveling off can be observed in PM_10-2.5 and PM_2.5 which points to a change in the tendency. Cluster analysis of the elements in the fine and coarse fractions were identified to evaluate trends in the contributing sources. In the fine fraction, the mass contribution of crustal elements (Si, Al, Ca and Fe) has remain stable in the last 8 years, mass contribution of elements (Pb, Br and Cl) associated to anthropogenic sources (traffic, wood burning) has also remained stable in the same period. For the coarse fraction, the contribution of one group of elements associated to crustal or anthropogenic sources has remained stable and another group has decreased in the last 8 years. The leveling off can be ascribed to decreased rainfall during the last 8 years that have promoted soil dryness and re-suspension of dust facilitated by wind or vehicular traffic. Mean temperatures have increased in the last 30 years, but have not contributed directly to the leveling of the concentration.

摘要

研究了在智利圣地亚哥市区的Parque O'Higgins站收集的每日细颗粒物（PM _2.5）和粗颗粒物（PM _10-2.5）的样品，以发现1998年至2018年的浓度趋势。使用X-获得元素浓度射线荧光。先前研究的回归模型表明，自1988年以来，PM _2.5和PM _10-2.5的比例一直在持续下降，这主要是由于几十年来采取了多项政策控制措施。PM _2.5已从1988年的68.3下降到2018年的27.6μg / m ³（60.4％）。但是，如果仅考虑最近的8年（2011年至2018年），则可以在_10-2.5和PM处观察到_持平2.5这表明趋势发生了变化。确定了对细颗粒和粗颗粒中的元素进行聚类分析，以评估贡献来源的趋势。在细小部分中，地壳元素（Si，Al，Ca和Fe）的质量贡献在过去8年中保持稳定，与人为源（交通，木材燃烧）相关的元素（Pb，Br和Cl）的质量贡献同期也保持稳定。对于粗略部分，在过去的8年中，一组与地壳或人为源相关的元素的贡献保持稳定，而另一组则有所下降。平稳的原因可以归因于过去8年中降雨的减少，这增加了土壤的干燥性，并且通过风或车辆交通促进了灰尘的重新悬浮。