Fossil and non-fossil sources of the carbonaceous component of PM 2.5 in forest and urban areas

Atmospheric particulate matter (PM 2.5 ) can damage human health. Biogenic organic compounds emitted from trees may increase the concentration of PM 2.5 via formation of secondary aerosols. Therefore, the role of biogenic emissions in PM 2.5 formation and the sources of PM 2.5 need to be investigated. Dual carbon isotope and levoglucosan analyses are powerful tools to track the sources of total carbon (TC) in PM 2.5 . We collected a total of 47 PM 2.5 samples from 2019 to 2020 inside a pine forest and in urban areas in South Korea. The average δ 13 C and Δ 14 C of TC in PM 2.5 at the Taehwa Research Forest (TRF) were − 25.7 and − 380.7‰, respectively, which were not significantly different from those collected at Seoul National University (SNU) in urban areas. Contribution of fossil fuel, C 3 -, and C 4 - plants to carbonaceous component of PM 2.5 were 52, 27, and 21% at SNU, whereas those were 46, 35, and 19% at TRF, respectively. The biomass burning tracer, levoglucosan, was most abundant in winter and correlated with the contribution of C 4 plants derived carbon. Results indicate that biogenic aerosols emitted from trees is less likely to be an important source of PM 2.5 and that trees can act as a bio-filter to reduce PM 2.5 .