First insights into the molecular characteristics of atmospheric organic aerosols from Iasi, Romania: Behavior of biogenic versus anthropogenic contributions and potential implications

Cornelia Amarandei; Romeo Iulian Olariu; Cecilia Arsene

doi:10.1016/j.scitotenv.2023.162830

First insights into the molecular characteristics of atmospheric organic aerosols from Iasi, Romania: Behavior of biogenic versus anthropogenic contributions and potential implications

Sci Total Environ. 2023 Jun 15:877:162830. doi: 10.1016/j.scitotenv.2023.162830. Epub 2023 Mar 15.

Authors

Cornelia Amarandei¹, Romeo Iulian Olariu¹, Cecilia Arsene²

Affiliations

¹ "Alexandru Ioan Cuza" University of Iasi, Faculty of Chemistry, 11 Carol I, 700506, Iasi, Romania; "Alexandru Ioan Cuza" University of Iasi, Integrated Centre of Environmental Science Studies in the North Eastern Region (CERNESIM), 11 Carol I, 700506, Iasi, Romania; "Alexandru Ioan Cuza" University of Iasi, Research Center with Integrated Techniques for Atmospheric Aerosol Investigation in Romania (RECENT-AIR), 11 Carol I, 700506, Iasi, Romania.
² "Alexandru Ioan Cuza" University of Iasi, Faculty of Chemistry, 11 Carol I, 700506, Iasi, Romania; "Alexandru Ioan Cuza" University of Iasi, Integrated Centre of Environmental Science Studies in the North Eastern Region (CERNESIM), 11 Carol I, 700506, Iasi, Romania; "Alexandru Ioan Cuza" University of Iasi, Research Center with Integrated Techniques for Atmospheric Aerosol Investigation in Romania (RECENT-AIR), 11 Carol I, 700506, Iasi, Romania. Electronic address: carsene@uaic.ro.

PMID: 36924952
DOI: 10.1016/j.scitotenv.2023.162830

Abstract

The present study reports first data on the organic molecular composition and evolution of secondary organic aerosols (SOAs) markers in aerosol samples from an urban environment in Romania. Targeted and non-targeted approaches of liquid chromatography tandem with time-of-flight mass spectrometry (LC-ToF-MS) were used as powerful analytical approaches for aerosol characterization at the molecular level. Four distinct organic molecular groups (CHO, CHON, CHONS, and CHOS) were classified as relevant for both warm (with 847 assigned molecular formulae) and cold (with 432 assigned molecular formulae) periods. Different formation mechanisms, physico-chemical processing, meteorological conditions, and sources origin or strengths (biogenic versus anthropogenic), were identified as governing factors of the mass concentration size distribution for the first generation and second-generation oxidation products of α-/β-pinene and two nitroaromatics (i.e., 4-nitrophenol and 4-nitrocatechol). Aromaticity equivalent (X_C), carbon oxidation state (OS_C), H/C and O/C ratios, and van Krevelen diagrams, were used to discriminate between: i) the aliphatic or aromatic nature of the identified organic aerosol constituents, ii) the oxidation state of the aerosol samples (e.g., more oxidized molecular formulae during the highly insolated period, more intense photochemistry), and iii) sources role in controlling OAs constituents abundances and behavior (e.g., higher relative contributions of aliphatic CHO formulae with a wider range of carbon numbers and CHOS molecular group with higher contribution during the warm period due to increased biogenic emissions or secondary formation from the biogenic precursors). Since in the present study >88 % of the 4-nitrocatechol and 4-nitrophenol was determined in the aerosol size fraction below 1 μm, it is believed that determination of their abundances and size distribution in ambient aerosols might provide direction for future studies such as to enhance the knowledge on their toxic potential levels for the human health.

Keywords: 4-Nitrocatechol; 4-Nitrophenol; LC-ToF-MS; Molecular formula groups; Monoterpene markers; Secondary organic aerosols; Size-segregated aerosols.