Variations of concentration of aerosol particles (<10 μm) in Vilnius
AbstractLong-term observations of atmospheric constituents such as particulate matter (PM) are increasingly important in evaluating their adverse effects on human health and climate. Time series (2005–2007) of the hourly mass concentrations of PM10 recorded at three air quality monitoring (AQM) sites characterized by a different exposure to traffic emissions in Vilnius city have been used for the investigation of spatial and temporal variations as well as the input of pollutants to PM10 levels by long-range transport of air masses. The distribution plots of PM10 24-h mean mass concentrations showed a unimodal lognormal distribution with the mode centered on 34.4, 21.6, and 19.9 μg/m3, respectively, at the trafc-exposed (Žirmūnai), semi-urban (Senamiestis), and urban background (Lazdynai) sites. The difference between traffic-exposed and urban background data indicates average concentration increment of 12.5 μg/m3 of PM10. Site-specific, clear diurnal and seasonal fluctuations were observed for PM10 concentrations at all AQM sites. Two major pollution episodes when PM10 24-h mean exceeded 50 μg/m3 were differentiated. The first one (25 April – 15 May 2006) was characterized by the long-range transport of pollutants emitted by biomass burning in southeastern Europe. In the second episode (9–17 January 2009), high levels of PM10 were determined, tracing the polluted air mass transport from southwestern Europe where large combustion plants are responsible for two thirds of the European Union (EU) total sulphur emissions.
Keywords: PM10, mass concentration, statistical analysis, intraurban uniformity, long-range transport, air mass backward trajectories
PACS: 92.60.Mt, 92.60.Sz, 92.20.Bk