The effect of restrictions caused by COVID-19 pandemic in Novosibirsk in spring 2020 on the composition of trace atmospheric gases and organic aerosol in the air of Novosibirsk Akademgorodok is investigated. The concentrations of aldehydes (formaldehyde, acetaldehyde, benzaldehyde, acrolein, and substituted aromatic aldehydes), the corresponding carboxylic acids, and peroxy compounds were studied before and after adoption of restrictions, prior to the start of vegetation period, that is, with the minimal emission of biogenic compounds into the atmosphere. Differences in diurnal variations and the composition of hydroperoxides are revealed at the background of weakening of anthropogenic sources. The role of hydroperoxides in gas-to-particle conversion is shown. In parallel, the concentrations of nanometer-sized aerosol particles were measured, and differences in their chemical composition are analyzed. To explain the observed changes in the composition of organic aerosol, numerical simulation of the stages leading to the formation of condensable products was carried out. A sharp decrease in the strength of anthropogenic sources allowed us to reveal and characterize the contribution from biogenic sources into the formation of organic atmospheric aerosol and to describe this process.
atmospheric organic aerosol, formaldehyde, acetaldehyde, aromatic aldehydes, aerosol formation
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