Differences in stable carbon isotopic composition in the fine bulk aerosol and gas phases based on seasonally resolved data at a Prague site

Isotope fractionation between the gas and aerosol phases is an important phenomenon in terms of studying atmospheric processes. Here, we studied seasonal variations in the stable carbon isotope ratio (δ¹³C) of total carbon (TC; δ¹³C_TC) and water-soluble organic carbon (WSOC; δ¹³C_WSOC) in fine aerosol particles (PM_2.5) as well as in the total carbon of the gas phase (TCgas; δ¹³C_TCgas) at a suburban site in Prague, Czech Republic, Central Europe. The most ¹³C enrichment was found in WSOC, followed by particulate TC, whereas the most ¹³C depletion was found in gaseous TC. The clear seasonal pattern for all δ¹³C values (with the highest values in winter and lowest in summer) provides evidence for the presence of different aerosol sources at the site during the year. Despite the different seasonal compositions of carbonaceous aerosols, the isotope differences (Δδ¹³C) between the analyzed bulk aerosol parts and phases were similar during the seasons. This shows that the fractionation of stable carbon isotopes is a predominantly physical process in which the chemical composition of individual compounds in bulk aerosols does not play a major role.

Acknowledgement: This conference contribution was supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project No. LM2018122, by the ERDF project "ACTRIS-CZ RI" (No. CZ.02.1.01/0.0/0.0/16_013/0001315) and by the Japan Society for the Promotion of Science (JSPS) through Grant-in-Aid No. 24221001. We appreciate the financial support of JSPS fellowship to P. Vodička (P16760) in Japan.

Reference: Vodička, P., Kawamura, K., Schwarz, J., Ždímal, V.: Seasonal changes in stable carbon isotopic composition in the bulk aerosol and gas phases at a suburban site in Prague, Sci. Total Environ., 803, 149767, 2022. https://doi.org/10.1016/j.scitotenv.2021.149767.