engleski

MASS CONCENTRATIONS OF CARBON POLLUTANTS AT A TYPICAL STREET CANYON LOCATION

Narrow city streets engulfed by tall buildings are favourable to a general effect of a “canyon” in which pollution accumulates strongly on a relatively small area because of weak or inexistent ventilation. The most important anthropogenic sources of primary particulate matter in cities are exhaust and non-exhaust emissions from road traffic as well as incomplete fuel combustion (diesel and gasoline) but they can also originate from resuspension from street surfaces. PM1 (particulate matter with an aerodynamic diameter under 1 μm) mass concentration and its chemical composition depend strongly on meteorological factors (i.e., low ambient temperatures, temperature inversions), traffic, as well as street geometry. Especially in a canyon type street, the exhausts of motor vehicles accumulate and harm travellers, which are directly exposed to the atmosphere. Long and short-term exposure to ambient air pollution can trigger acute, chronic illness (cardiovascular diseases and asthma) or infectious diseases, preterm birth, earlier mortality and adverse neuropsychological effects. The aim of this study was to determine and compare levels of elemental carbon (EC), organic carbon (OC), total carbon (TC), water soluble OC (WSOC), polycyclic aromatic hydrocarbons (PAHs) and levoglucosan (LVG) mass concentrations and black smoke index (IBS) in PM1 particles between the colder (January-March) and warmer (April-June) part of the year at one street canyon location in the centre of Zagreb during 2019. Daily samples of airborne particles were collected on pre-fired quartz fibre filters from January to June 2019. PM1 mass concentrations were determined gravimetrically. Samples were analysed for OC, TC, WSOC and EC with thermal/optical transmittance method (TOT) using a EUSAAR_2 protocol, PAHs with high performance liquid chromatograph (HPLC) with a fluorescence detector and time programmed changes in excitation and emission, levoglucosan with high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) while IBS was determined with the Smokestain reflectometer EEL43M. Preliminary measurements showed seasonal variations of mass concentrations for carbon species in PM1. The higher concentrations were observed during the cold periods of the year, while lower concentrations were recorded during the warmer period. Data analysis indicate that carbon content in particulate matter may be influenced by traffic and traffic jams due to the increased number of traffic lights and vehicles standing with engines running. The reducing particle concentration could be due to vehicles standing more than moving and raised less dust from the road itself. Therefore, a lower temperature during wintertime favours the condensation of organic compounds onto pre- existing particles and higher OC mass concentrations and OC content in PM1.

EC ; OC ; TC, WSOC, PAH

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