Predominance of secondary organic aerosol to particle-bound reactive oxygen species activity in fine ambient aerosol

Abstract

Abstract. Reactive oxygen species (ROS) are believed to contribute to the adverse health effects of aerosols. This may happen by inhaled particle-bound (exogenic) ROS (PB-ROS) or by ROS formed within the respiratory tract by certain aerosol components (endogenic ROS). We investigated the chemical composition of aerosols and their exogenic ROS content at the two contrasting locations Beijing (China) and Bern (Switzerland). We apportioned the ambient organic aerosol to different sources and attributed the observed water-soluble PB-ROS to them. The oxygenated organic aerosol (OOA, a proxy for secondary organic aerosol, SOA) explained the highest fraction of the exogenic ROS concentration variance at both locations. We also characterized primary and secondary aerosol emissions generated from different biogenic and anthropogenic sources in smog chamber experiments. The exogenic PB-ROS content in the OOA from these emission sources was comparable to that in the ambient measurements. Our results imply that SOA from gaseous precursors of different anthropogenic emission sources is a crucial source of water-soluble PB-ROS and should be additionally considered in toxicological and epidemiological studies in an adequate way besides primary emissions. The importance of PB-ROS may be connected to the seasonal trends in health effects of PM reported by epidemiological studies, with elevated incidences of adverse effects in warmer seasons, which are accompanied by more-intense atmospheric oxidation processes.

Source apportionment of atmospheric PM<sub>10</sub> Oxidative Potential: synthesis of 15 year-round urban datasets in France

“…We also observed a clear distinction between the intrinsic OP values for the different PM sources, ranging from 0.044 ± 0.064 nmol min −1 µg −1 to 0.223 ± 0.085 nmol min −1 µg −1 for the OP DTT and from −0.018 ± 0.152 nmol min −1 µg −1 to 0.197 ± 0.104 nmol min −1 µg −1 for the OP AA . Such results agree with previous studies reporting different reactivity (or intrinsic OP) for different sources based on receptor-model techniques (Ayres et al, 2008;Bates et al, 2015;Cesari et al, 2019;Costabile et al, 2019;Fang et al, 2016;Paraskevopoulou et al, 2019;Perrone et al, 2019;Verma et al, 2014;Weber et al, 2018;Zhou et al, 2019;Daellenbach et al, 2020).…”

“…The source apportionment of the OP can be performed in two main ways: 1) by including the OP as an input variable for receptor-model (RM) (Verma et al, 2014;Fang et al, 2016;Ma et al, 2018;Cesari et al, 2019) or 2) by conducting source attribution to the PM mass and then, using a multiple linear regression (MLR) model, assigning OP to each of the sources from the source-receptor model (Bates et al, 2015;Verma et al, 2015b;Weber et al, 2018;Cesari et al, 2019;Paraskevopoulou et al, 2019;Zhou et al, 2019;Daellenbach et al, 2020). We decided to use the second approach since adding the OP variable to the PMF may change the source apportionment solution.…”

“…The dithiothreitol (DTT) and ascorbic-acid (AA) assays are widely used in associations with health endpoints (Abrams et al, 2017;Atkinson et al, 2016;Bates et al, 2015;Canova et al, 2014;Fang et al, 2016;Janssen et al, 2015;Strak et al, 2017a;Weichenthal et al, 2016;Yang et al, 2016;Zhang et al, 2016) even if the exact methodologies differ from one study to the other. Results can also differ for the seasonality of OP based on these two assays and some studies report strong seasonality of OP whereas others don't (Bates et al, 2015;Calas et al, 2019;Cesari et al, 2019;Fang et al, 2016;Ma et al, 2018;Paraskevopoulou et al, 2019;Perrone et al, 2016;Pietrogrande et al, 2018;Verma et al, 2014;Fang et al, 2015;Weber et al, 2018;Borlaza et al, 2018;Zhou et al, 2019).…”

“…Finally, several studies have already shown that different sources of PM have different reactivity to OP tests (Verma et al, 2014;Bates et al, 2015;Fang et al, 2016;Weber et al, 2018;Paraskevopoulou et al, 2019;Cesari et al, 2019;Zhou et al, 2019;Daellenbach et al, 2020). In particular, sources with high concentrations of transition metals, such as road traffic, appear to have a higher intrinsic oxidative potential (i.e.…”

Effect of Renewable Fuels and Intake O2 Concentration on Diesel Engine Emission Characteristics and Reactive Oxygen Species (ROS) Formation

“…Other studies have linked ROS formation to organic components [69] and metal components. We therefor investigated the correlation between ROS and the chemical composition.…”