Magnetic and analytical fingerprinting of particulate matter for urban (bio)monitoring
21 January 2020
Stadscampus, Promotiezaal "De Grauwzusters" - Lange Sint-Annastraat 7 - 2000 Antwerpen (route: UAntwerpen, Stadscampus
Organization / co-organization:
Department of Bioscience Engineering
Roeland Samson & Karolien De Wael
PhD defence Ana Castanheiro - Faculty of Science, Department of Bioscience Engineering
Particulate matter (PM), the collection of fine respirable particles suspended in the air, is the greatest health-threatening pollutant. To properly monitor the high spatial variability of PM is not possible at the moment, particularly within dynamic, mixed-source urban environments, as conventional air quality monitoring networks have limited spatial resolution and often lack information on PM composition. To use urban vegetation as a bio-indicator for atmospheric PM (biomonitoring), as it provides a natural surface for deposition of particulates, may help filling out those gaps. Iron and other metals are of particular interest within PM. Therefore, biomagnetic monitoring of leaves has been extensively used as a rapid and cost-effective tool to assess urban PM exposure.
Leaves exposed to atmospheric conditions leads to the invariable accumulation of magnetic particles, which are ubiquitously present in PM but allow distinguishing between low and high pollution levels. Throughout this PhD research, the applicability of biomagnetic monitoring as a fingerprinting tool for atmospheric PM was investigated across different environments and source types, using a combination of analytical techniques. Overall this consisted in 1) characterizing major urban source types of PM by means of magnetic, chemical and microscopic techniques, to obtain source-specific magnetic and physicochemical PM fingerprints, 2) investigating potential associations source-specific magnetic and physicochemical PM fingerprints, and 3) evaluating leaf biomagnetic monitoring as a strategy to infer atmospheric PM levels and characteristics of major PM contributing sources.
Leaf-deposited PM from environments mainly exposed to different pollution sources were first investigated microscopically for their morphological characteristics and elemental composition. In a second stage, dedicated particle-analysis was combined with leaf magnetic investigation to discriminate between different source types (small scale) and between urban streets and parks across 20 European cities (large scale). To gain more insight on the leaf accumulation of PM, a multi-approach leaf monitoring campaign was also conducted using plant species with distinct macro- and micro-morphology.
The information gathered on the analytical techniques used and their potential for source characterization were finally applied in a large PM fingerprinting (PMF) project. The PMF project comprised the monitoring and fingerprinting of five different source locations (road, railway and shipping traffic, industry and a background site) based on air-pumped samples (conventional monitoring) and exposed plant leaves, to obtain source-specific signatures and evaluate the applicability of leaf magnetic monitoring of PM. The health-risk potential of the studied source types was also explored in terms of human lung pro-inflammatory response.