Abstract
Between June and September 2018, particulate matter (PM) samples were taken in the Sartenejas Valley, southeast of Greater Caracas, Venezuela. The aim was to evaluate the morphology and the elemental chemical composition of particulate matter and establish possible emission sources during the rainy season. Functional groups were identified by FTIR spectroscopic analysis, and morphology and elemental composition were obtained by SEM–EDX analysis. The sampling period coincided with a Sahara dust storm. The SEM–EDX and FTIR analyses found evidence of mineral elements related to soil and crustal origins. The presence of C-rich or C-containing aerosols is related to biological sources or mineral carbon. SEM–EDX analysis of PM revealed the following particle groups: geogenic, metallic, C-rich, and secondary aerosols. Quantitative source appointments through principal component analysis (PCA) corroborated PM sources, including soil dust, sea salts, and reacted aerosols. According to the authors’ knowledge, this study represents the first report to indicate that an episode of African dust could influence the particles collected in an intertropical continental sector in Venezuela, South America.
Highlights
Particulate matter (PM) refers to any substance, except pure water, that exists as a liquid or solid in the atmosphere under normal conditions and is microscopic or submicroscopic but larger than molecular dimensions (Seinfeld and Pandis 2016)
The scanning electron microscopy (SEM)–EDX analysis found evidence of mineral elements related to soil and crustal origins, some of which were identified by Fourier transform infrared spectroscopy (FTIR) analysis due to characteristic absorption peaks spectra
By SEM–EDX analysis, some particles with varying amounts of C were associated with biological sources
Summary
Particulate matter (PM) refers to any substance, except pure water, that exists as a liquid or solid in the atmosphere under normal conditions and is microscopic or submicroscopic but larger than molecular dimensions (Seinfeld and Pandis 2016). PM can be classified according to its aerodynamic diameter (Dp) in P M2.5 (Dp ≤ 2.5 μm), PM10 (Dp ≤ 10 μm), and TSP (total suspended particles) (Dp ≤ 70 μm). The PM2.5 is called fine fraction and particles between. The most petite particle sizes (including PM2.5) have the most negative impacts on human health and climate change (Cohen et al 2017; Yin et al 2020; HEI 2019). PM may have a natural or anthropogenic origin; particles of natural origin come from soil erosion, resuspended soil dust, sea salt transport, forest fires, volcanic eruptions, and fractionated biological material emissions. Particles of anthropogenic origin result from human activities as vehicular traffic (mainly from vehicles with diesel engines), combustion and industrial processes, mining-metallurgical activity, and biomass burning (Aragón-Piña, 2011a, b)
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