Emission Ratios and Source Identification of VOCs in Moscow in 2019–2020

Abstract

Measurements of CO and 15 volatile organic compounds (VOCs) at the IAP-RAS (A.M. Obukhov Institute of Atmospheric Physics) site located in the center of Moscow were analyzed. Acetaldehyde, ethanol, 1.3-butadiene, isoprene, toluene and C-8 aromatics were established to be the main ozone precursors in the observed area, providing up to 82% of the total ozone formation potential of the VOCs measured. Diurnal and seasonal variations of the compounds are discussed. The concentrations of anthropogenic VOCs (acetaldehyde, benzene, 1.3-butadiene, toluene, and C-8 aromatics) did not exceed their maximum permissible levels, reaching their maxima in summer and autumn in the morning and evening hours. Biogenic ethanol and isoprene were the highest in summer midday but their concentrations were low enough (up to 4 and 0.4 ppbv, respectively) due to small vegetation area around the site. Emission ratios (ERs) for the main ozone precursors—acetaldehyde, ethanol, 1.3-butadiene, isoprene, toluene, and C-8 aromatics—were estimated from two-sided linear regression fits using benzene and CO as tracers for anthropogenic emissions, with spatial and temporal filters being applied to account for the influence of chemistry and local emission sources. The best estimates of ERs were obtained using benzene as a reference species. Anthropogenic fractions of VOCs (AFs) were then estimated. As expected, acetaldehyde, toluene, 1.3-butadiene, and C8aromatics were entirely anthropogenic and emitted mainly from urban vehicle exhausts throughout the day, both in summer and in winter. AFs of isoprene and ethanol did not exceed 30% and 50% in summer, respectively, during both daytime and nighttime hours. In winter, the anthropogenic fractions of isoprene and ethanol were slightly higher (up to 35% and 60%, respectively).

Variations of Organic and Inorganic Atmospheric Boundary Layer Gaseous Species by Observations in Moscow and Zvenigorod

“…Figure 7 shows the diurnal variations obtained from the PTR-MS observations on the ZSS. The diurnal variations of such VOCs as acetone and acetic acid are completely similar to those for observations in a metropolis [Belikov et al, 2019;Berezina et al, 2020Berezina et al, , 2022Jordan et al, 2009]. The concentrations of these VOCs, both in the metropolis and in the countryside, have a pronounced maximum in the daytime, and a minimum -at night.…”

“…The nitrogen monoxide concentrations peaks at Figure 5 between 0:00 and 5:00 o'clock could be explained by complex pollutant emission sources at the densely built area surrounding the measuring site [Berezina et al, 2022]. Measurements at the ZSS (Figure 6), where there are no such emission sources, don't show such peaks, as well as measurements at the site in Moscow, but located far from local emission sources [Elansky et al, 2007].…”

“…Measurements of the concentrations of minor gaseous species in the atmospheric surface layer were carried out using automated integrated hardware and software systems developed and manufactured at the IAP RAS (hereinafter -complexes) [Berezina et al, 2020[Berezina et al, , 2022. The complexes are built on the basis of a set of measuring instruments manufactured by leading foreign and domestic manufacturing companies.…”

“…This method was first developed in 1995 at the Institute of Ion Physics of the University of Innsbruck (Austria) [de Gouw and Warneke, 2006]. In recent years, instruments of this type have become widely used for observing VOCs concentrations in the atmosphere [Belousov et al, 2018;Berezina et al, 2020Berezina et al, , 2022Jordan et al, 2009;Taipale et al, 2008].…”

“…The PTR-MS instrument was periodically calibrated using permeation tubes. The calibration procedure was in detail described in [Berezina et al, 2022]. Functioning checking and calibration of other instruments is carried out out at least quarterly, using calibration gas mixtures manufactured by the company "Linde Gas Rus" (Russia, Balashikha), with accuracy of about 4%.…”