Comparison of Plant-derived Carbonaceous Components (Organic Molecular Markers and 14carbon) in PM2.5 in Summer and Autumn at Kazo, Japan

Abstract

In Japan, the primary carbonaceous particles emitted from motor vehicles and waste incinerators have been reduced due to strict regulations against exhaust gas. However, the relative contribution of carbonaceous particles derived from plants and biomass has been increasing. Accordingly, compositional analysis of carbonaceous particles has become increasingly important to determine the sources and types of particles produced. To reveal the sources of the organic particles contained in particulate matter with diameters of ≤ 2.5 μm (PM2.5) and the processes involved in their generation, we analyzed molecular marker compounds (2-methyltetrols, cis-pinonic acid, and levoglucosan) derived from the plants and biomass in the PM2.5 collected during daytime- and nighttime-sampling periods in summer (July and August) and autumn (November) in Kazo, which is in the northern area of Saitama prefecture, Japan. We also measured 14C carbonaceous concentrations in the same PM2.5 samples. The concentrations of 2-methyltetrols were higher in the summer than in the autumn. Because the deciduous period overlaps with this decrease in the levels of 2-methyltetrols, we considered the emission source to broad-leaved trees. In contrast, the emission source of the cispinonic acid precursor was considered to be conifers, because its concentration remained almost constant throughout the year. The concentration of levoglucosan was considerably increased in the autumn due to frequent biomass open burning. The ratio of plant-derived carbon to total carbon, obtained by measuring of 14C, in summer PM2.5 sample was higher in the nighttime, and could be influenced by anthropogenic sources during the daytime.

Keywords

• biomass burning
• carbon isotopic analysis
• fossil fuels
• molecular marker
• secondary formation