Particle analysis on urban green: a record of urban particulate matter pollution
Particulate matter (PM), which consists of a panoply of fine respirable particles suspended in the air, is one of the major health-threatening air pollutants. Anthropogenic PM sources include the burning of fossil fuels (for electricity generation, transport, industry and households), industrial processes, waste treatment and agriculture; in addition to the combustion-derived particles, vehicle traffic is also responsible for the release of abrasion metallic particles due to the wear of vehicle components and the friction between vehicles and the pavement (cars and road, trains and railway track). The large diversity of pollution sources, with especial abundance within urban environments, makes that PM pollution displays a wide range in size, shape and chemical composition. Particle characterization of the different sources of PM emissions is essential to better understand their contribution to the urban-mixed source atmosphere, as well as their relevance to human health. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX) allows the high-resolution examination of nano- to micrometer particles; determination of their size and shape, and estimation of their chemical content are the main outcomes of this particle-based analysis.
As an alternative to airborne samples collected via high-volume samplers or impactors, urban green is herein used as a recorder of atmospheric particle pollution. Plant leaves and bark wood samples are examples of biological accumulation matrices of atmospheric particles, therefore studied for biomonitoring/source characterization purposes. These biological substrates are also investigated in terms of their micro-surface characteristics, such as roughness, hairiness, and presence of stomata. Species-dependency and spatiotemporal variations are also targets of our study.
Leaf-deposited particles on the adaxial and abaxial surface of ivy leaves.
Investigation of micro-surface characteristics (e.g. roughness, hairiness) for different plant species.