Variability and temporal structure of concentrations of carbon monoxide in Poznan (central-western Poland)

Carbon monoxide, in addition to CO2 and CH4, constitutes the largest source of carbon in the atmosphere and. by reacting with the hydroxyradical OH, it indirectly contributes to the increase in the concentration of methane and ozone in the atmosphere. The aim of the study was to determine the temporal variation of CO concentrations and its dependence on the weather course in an urban area situated in Wielkopolska, a region in central-western Poland. The research used data from the State Environmental Monitoring Station in the north-western part of Poznań (Hs = 84 m above sea level) in the immediate vicinity of a residential and recreational area. The data included hourly concentrations of CO and hourly values of atmospheric pressure, air temperature, total solar radiation, relative air humidity and wind velocity in 2005-2014. To measure the concentration of carbon monoxide, a Horiba APMA 360 analyzer and TELEDYNE API T400 were used. The measurement method was infrared spectroscopy. The time distribution of CO concentrations was considered by years, half years, months and hours. Relationships between the analyzed variables were confirmed using the Spearman’s correlation coefficient at the level of p ≤ 0.01. It was found that in the years of research the average concentration of CO in central-western Poland had a negative trend, as well as higher values in the heating season than in the warm half of year, and on week days than at weekends. Two concentration maxima, morning and evening ones, both in warm and cool half-year and on working days, were observed. On non-working days, there was one evening maximum. The variability of CO was mostly affected by air temperature (rs = -0.45) and solar radiation (rs = 0.32). The highest concentrations of CO were accompanied by the lowest values of solar radiation, air temperature and wind velocity, and highest values of the atmospheric pressure, as well as higher than average relative air humidity.