Investigation of the Relations between Biogenic and Anthropogenic Sources of Organic Atmospheric Aerosol under Conditions of Restrictions Due to the Coronavirus Pandemic

Abstract

—The effect of restrictions caused by the 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 the adoption of restrictions, prior to the start of growing season, that is, with the minimal emission of biogenic compounds into the atmosphere. Differences in diurnal variations and the composition of hydroperoxides are revealed on a background of weakening 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 were analyzed. To explain the observed changes in the composition of organic aerosol, the stages formation of condensable products was numerically simulated. A sharp decrease in the strength of anthropogenic sources allowed us to reveal and characterize the contribution from biogenic sources to the formation of organic atmospheric aerosol and to describe this process.