Contributions of Open Burning to PM2.5 in Suburban Tokyo and the Impact of Biomass Smoke on Cellular Redox Activity

Abstract:

Fine atmospheric particles (PM_2.5) in suburban Tokyo (Tsukuba), Japan were collected for 24 h every week over the course of a full year (2012–2013) to estimate the source contributions with a focus on open burning of crop residues. Using the quartz fiber filter-collected samples, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), inorganic ionic species, and organic markers were measured. More than 100 organic markers including levoglucosan, a marker of open burning, were measured using gas chromatography/mass spectrometry (GC/MS) after derivatization. Using the Teflon filter-collected samples, particulate mass, elements, and biological redox activity using an in-vitro rat alveolar macrophage reactive oxygen species (ROS) assay were measured. The PM_2.5 concentrations were higher in February–March and the annual average was 13.6 μg m^–3. The EC and OC concentrations were higher in March and September. Levoglucosan concentrations were remarkably higher in fall and winter (September–March) with maximum in November, suggesting enhanced biomass burning contribution. The ROS activity of the PM_2.5 (per air volume) was higher in spring (April) and summer (July). PM_2.5 sources as estimated by a chemical mass balance model using the organic markers, and relationships of redox activity with chemical species and emission sources will be presented.