Ionic composition of PM2.5 particle fraction at a coastal urban background site in Croatia
2020
Gluščić, Valentina | Čačković, Mirjana | Pehnec, Gordana | Bešlić, Ivan
The mass concentrations and content of water-soluble anions (Cl⁻, NO₃⁻, SO₄²⁻) and cations (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) in the PM₂.₅ particle fraction were measured, and an investigation of their relationship and their contribution to the total PM₂.₅ mass measured was conducted at an urban background site as part of the Croatian monitoring network for air quality located in Rijeka, Croatia. Daily samples of PM₂.₅ particle fraction were collected over 2017 on PTFE filters using a low volume sampler Sven Leckel SEQ 47/50. Mass concentrations of the PM₂.₅ particle fraction were determined by gravimetry according to the standard HRN EN 12341:2014 (EN 12341:2014). The content of water-soluble inorganic anions and cations were determined using a Thermo Scientific ICS-5000 capillary ion chromatograph. Results show that the annual average PM₂.₅ mass concentration was 9.65 μg m⁻³ and did not exceed the limit value of 25 μg m⁻³ given by the Regulation on the level of pollutants in air (OG No. 117/12). The annual average mass concentrations of ions in PM₂.₅ particle fraction was SO₄²⁻> NH₄⁺> NO₃⁻ > Ca²⁺> K⁺> Na⁺> Cl⁻ > Mg²⁺. The contributions of total anion mass and total cation mass to the total PM₂.₅ mass were 25.4% and 12.8%, respectively. The acidic property of PM₂.₅ was obtained in spring and winter and slightly acidic in summer and autumn. For a prediction of the pollutant sources, we ran a factor analysis which was performed using the statistical packages STATISTICA 13.0. After varimax rotation, the obtained four principal component factors were found to account for 86% of the variance. Factor loadings > 0.7 were considered significant.
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