Measurement report: Chemical components and ¹³C and ¹⁵N isotope ratios of fine aerosols over Tianjin, North China: year-round observations

Abstract. To better understand the origins and seasonality of atmospheric aerosols in North China, we collected fine (PM2.5) at an urban site (Nankai District, ND) a suburban (Haihe Education Park, HEP) Tianjin from July 2018 to 2019. The PM2.5 was studied for carbonaceous, nitrogenous ionic components stable carbon nitrogen isotope ratios total (δ13CTC) (δ15NTN). On average, mass concentrations PM2.5, organic (OC), elemental (EC) water-soluble OC (WSOC) were higher winter than summer both ND HEP. SO42-, NO3- NH4+ dominant ions, their sum accounted 89 % 87 peaked minimum summer, whereas SO42- all other seasons HEP comparable among seasons, although it ND. δ13CTC δ15NTN −26.5 ‰ −21.9 +1.01 +22.8 −25.5 −22.8 +4.91 +18.6 Based on seasonal variations measured parameters, found that coal biomass combustion emissions are sources autumn winter, while terrestrial and/or marine biological important spring region, China. In addition, our results implied secondary formation pathways autumn/winter different those spring/summer; i.e., they might be driven by NO3 radicals former period.