Morton-Bermea Ofelia, Garza-Galindo Rodrigo, Hernández-Álvarez Elizabeth, Amador-Muñoz Omar, Garcia-Arreola Maria Elena, Ordoñez-Godínez Sara L, Beramendi-Orosco Laura, Santos-Medina Graciela L, Miranda Javier, Rosas-Pérez Irma
Instituto de Geofísica, Universidad Nacional Autónoma de México, 04510, Cd. México, Mexico.
Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, 04510, Cd. de México, Mexico.
Environ Monit Assess. 2018 Jan 17;190(2):83. doi: 10.1007/s10661-017-6443-z.
The study of airborne metals in urban areas is relevant due to their toxic effects on human health and organisms. In this study, we analyzed metals including rare earth elements (REE) in particles smaller than 2.5 μm (PM), collected at five sites around the Mexico City Metropolitan Area (MCMA), during three periods in 2011: April (dry-warm season, DW), August (rainy season, R), and November (dry-cold season, DC). Principal component analysis allowed identifying factors related to geogenic sources and factors related to anthropogenic sources. The recognition of the high impact of geogenic sources in PM is in agreement with the REE distribution patterns, which show similar behavior as those shown by igneous rocks, confirming the influence of the regional geogenic material. Metals associated to geogenic sources showed higher concentration (p < 0.05) at NE of the MCMA and a significant correlation with prevalent winds. Geogenic metals show similar seasonal distribution, with the highest concentration during DW (p < 0.05), suggesting a possible metal resuspension effect which affects more significantly at lower relative humidity (RH). The metals associated with anthropogenic sources are in agreement with the urban complexity of the area, showing homogenous distribution throughout MCMA (p > 0.05) and no similar seasonal pattern among them. These unexpected results exposed outstanding information regarding the identification of different geogenic sources as the main contributors of metals in the atmospheric environment in the MCMA and highlighted the importance of meteorology in the spatial and seasonal metal patterns.
对城市地区空气中金属的研究具有重要意义，因为它们会对人类健康和生物体产生毒性影响。在本研究中，我们分析了2011年三个时期在墨西哥城大都市区（MCMA）周边五个地点采集的小于2.5微米颗粒物（PM）中的金属，包括稀土元素（REE）：4月（干暖季，DW）、8月（雨季，R）和11月（干冷季，DC）。主成分分析有助于识别与地质源相关的因素和与人为源相关的因素。认识到地质源对PM的高影响与REE分布模式一致，该模式显示出与火成岩相似的行为，证实了区域地质物质的影响。与地质源相关的金属在MCMA的东北部浓度较高（p < 0.05），且与盛行风显著相关。地质源金属呈现相似的季节分布，在DW期间浓度最高（p < 0.05），这表明可能存在金属再悬浮效应，在较低相对湿度（RH）下影响更为显著。与人为源相关的金属与该地区的城市复杂性相符，在整个MCMA中分布均匀（p > 0.05），且它们之间没有相似的季节模式。这些意外结果揭示了有关识别不同地质源作为MCMA大气环境中金属主要贡献者的重要信息，并突出了气象学在金属空间和季节模式中的重要性。
