Usage of Scanning Electron Microscopy for Particulate Matter Sources Identification

Abstract

Particulate matter (PM) diameter and shape are the most discussed physical properties considering behaviour characterisation, source identification, and possible effects on human health. Some groups of particles not only have a typical chemical composition but also a specific shape reflecting the method of their formation, so it is possible to deduce the source. A scanning electron microscope VEGA TS 5136 LSU (Tescan, s.r.o., Czech Republic) was used for PM imaging. PM air samples were captured on Millipore special filters made of polycarbonate membrane (Isopore) with a 0.6 µm size of pores. PM samples were taken both from near the exhaust of gasoline and diesel engines to define PM shapes emitted from combustion processes in vehicles, and also from chosen localities that represent urban sites with different traffic intensity and with different possible PM sources (transportation, industry). Samples of street dust were also collected by sweeping with a broom and with a vacuum cleaner to identify PM generated by resuspension. Separate spherical particles were observed on exposed filters near a gasoline vehicle's exhaust pipe and their aggregates near a diesel vehicle's exhaust. Spherical particles aggregates were also observed on filters exposed at a locality with a high traffic intensity where road traffic is considered to be the dominant source of air pollution. Larger spherical particles that represent the products of coal combustion were found at a locality near an industrial area. Other particle shapes, excluding spherical particles, were often observed at the localities that represent a more open area with more trees. Sharp-edged particles of geological origin (soils) and larger spherical or elongated particles of biological origin (spores) were also often observed on the filters from these localities which is evidence of a significant contribution of other processes to the overall PM air pollution, namely resuspension.

Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

“…Abrasion of individual components of the mixtures must be confirmed by means of chemical analysis of the particulates collected on nitrocellulose filters and its subsequent comparison with the composition of each tested mixture. Thus, obtained results presented in this paper were compared with data published in scientific literature [10], [11] in which the same PM shapes were observed and assigned to specific source.…”

“…Particulate matter (PM) is considered a mixture of chemical components originated from a variety of sources with specific physical parameters (such as shape, diameter, electric charge, solubility, surface of the particles) and chemical composition (organic and inorganic compounds). Sources, mechanisms of formation, meteorological conditions, distance from the source and other conditions determine these basic parameters [10]. To gain a better understanding of PM origin and behaviour, it is necessary to describe their chemical composition and size distribution.…”

“…As the angle of incidence increases, the emission distance of one side of the beam will decrease, and more secondary electrons will be emitted. Thus steep surfaces and edges tend to be brighter than flat surfaces, which results in images with a well-defined appearance [10], [11], [12].…”

Particulate matter (PM10) enhances RNA virus infection through modulation of innate immune responses

“…Characterization of PM 10 is of significant importance as it classifies the air pollutant into active and hazardous as well as non-active and unharmful particles. Many studies support the notion of PM characterization through SEM-EDS analysis and has reported different morphological shapes and chemical composition of PM, that cause severe lung diseases and illness ( Anake et al., 2016 ; Bahadar Zeb et al., 2018 ; Galvez et al., 2013 ; Genga et al., 2013 ; Grassi et al., 2004 ; Labrada-Delgado et al., 2012 ; Ličbinský et al., 2010 ; Ramirez-Leal et al., 2009 ; Ramirez-Leal et al., 2014 ; Tuvjargal et al., 2019 ). Then, we demonstrated the effectiveness of PM 10 exposure on A549 cells, by testing its inflammatory property within the cells, as it was previously reported that PM causes dysregulated inflammation in lungs to cause severe damage and toxicity ( Cevallos et al., 2017 ; de Barros Mendes Lopes et al., 2018 ; Horne et al., 2018 ).…”

Chemical composition, morphology, and distribution of particulate matter produced by road pavement abrasion using different types of aggregates and asphalt binder

“…Polycarbonate membrane filters were used for PM sampling (Willis et al, 2002). The particles trapped on the filters were covered with a 20-nm layer of gold for better monitoring of shape and size (Licbinsky et al, 2010;Weinbruch & Ebert, 2004). PM imaging was performed in the laboratory of the Transport Research Centre in Brno, Czech Republic.…”