engleski

CONTENT OF IONIC COMPOUNDS IN THE AMBIENT FINE PARTICULATE MATTER FRACTION

Because of its negative impact on human health, the climate and environment, the fine particulate matter fraction (PM2.5) presents a prominent environmental issue and is in the center of scientific concern. The most common natural sources of PM2.5 are sea spray and dust, while vehicular exhausts, shipping emissions, industrial emissions, agricultural activities and biomass burning are common anthropogenic sources. PM2.5 may also be formed as secondary aerosols from gaseous precursors through heterogeneous or homogeneous chemical reactions. Therefore, the complex chemical composition of PM2.5 is an outcome of the nature of the source. The aim of this study was to determine the mass concentrations of PM2.5 and water-soluble anions (Cl-, NO3 -, SO4 2-) and cations (Na+, NH4 +, K+, Mg2+, Ca2+) in PM2.5 and to investigate the possible seasonality in their levels, relations and contribution to the total PM2.5 mass. During the summer and winter of 2019, at an urban measuring station located at the northern part of the Adriatic coast in the city of Rijeka, daily samples of PM2.5 particle fraction were collected on PTFE filters using the Sven Leckel SEQ 47/50 low volume sampler. The mass concentration of PM2.5 was determined by gravimetric method. The content of water-soluble inorganic anions and cations were determined using a capillary ion chromatograph. Determined daily PM2.5 mass concentrations ranged from 1.4 μg m-3 to 47 μg m- 3. No significant difference in average PM2.5 mass concentrations was obtained between summer and winter. The determined daily mass concentrations of ions in PM2.5 particle fraction content ranged from 0 μg m-3 to 11.9 μg m-3. Results show significantly higher average mass concentrations of Cl-, NO3 -, Na+, K+, Mg2+, Ca2+ ion in PM2.5 in winter in comparison with the determined average values for summer, while the higher average mass concentration for SO4 2- and NH4 + ion in PM2.5 were obtained in summer. Contributions of each ion to the total PM2.5 mass ranged from 0.01 % to 29.2 %. The highest contribution to the total PM2.5 mass was obtained for SO4 2- and NH4 + in both seasons. The average contribution of total anion mass and total cation mass to the total PM2.5 mass was 29% and 13.4% in summer and 17.4% and 9.3% in winter, respectively. The obtained seasonal variations in mass concentrations of ionic species in PM2.5 and its contribution to the total PM2.5 mass indicated its different air pollution sources or formation pathways present in air in each season.

PM2.5 ; anions ; cations ; capillary ion chromatograph

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