Chemical composition and mass size distribution of fine particulate matter emitted by a small masonry heater

Residential wood combustion is a significant particulate emission source in many European countries. Especially for fine particle emissions in wood combustions, the lacking knowledge of emission factors (F-E) makes assessment of their contribution to ambient concentrations difficult. One reason for the discrepancy between modeled and measured contributions is many variables involved in combustion process. In this study, the fine particulate matter (PM) emissions coming from batch combustion of birch wood in a small masonry heater were investigated. The experiments were carried out in the specified conditions (normal and smouldering combustion, NC and SC, respectively). To enable various chemical analytical techniques, two sampling combinations for PM2.5 (particle diameter < 2.5 mu m), and size-segregated sampling were used. The samples were analyzed for gravimetric mass, major ions, monosaccharide anhydrides (MA, including levoglucosan, galactosan and mannosan), trace elements, elemental carbon (EC) and water-insoluble and -soluble particulate organic matter (WISPOM and WSPOM, respectively). F-E of PM2.5 based on gravimetric mass was three times higher for SC than for NC. Particulate organic matter (POM = 1.6 x OC) accounted for approximately 30% and 70% of F-E of PM2.5 in NC and SC, respectively. The corresponding values for EC were 32% and 25%. About 30% of the OC was water-soluble. Ions constituted about 20% of the F-E of PM2.5 in NC but only a few percents in SC. Potassium comprised around 60% of the analyzed ions. The fraction of trace elements consisting 94% of Zn was only about 1% of the total PM2.5 emissions. This study showed strong influence of combustion practice on emissions of the major chemical components from the small-scale wood combustion.