Naslov
Ozone and nitrogen dioxide concentrations in the Zagreb air

Autori
Pehnec, Gordana ; Vađić, Vladimira ; Hršak, Janko ; Šimić, Diana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Poster Abstracts 22nd International Conference on Information Technology Interfaces ITI 2000 / Kalpić, Damir ; Hljuz Dobrić, Vesna - Zagreb : Sveučilišni računski centar Sveučilišta u Zagrebu (Srce), 2000, 17-18

Skup
22nd International Conference on Information Technology Interfaces ITI 2000

Mjesto i datum
Pula, Hrvatska, 13.06.2000. - 16.06.2000

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
ozone; nitrogen dioxide; air pollution; functional principal components

Sažetak
Ozone (O3) is the main constituent of photochemical smog formed by the reaction of nitrogen dioxide (NO2) and volatile organic compounds to sunlight (WHO, 1987). This paper presents an analysis of temporal variation in O3 and NO2 concentrations in the Zagreb air, measured at four sites (Center, West, North and South) between March 1999 and February 2000. Concentrations of O3 were determined by active sampling of air in the absorption solution of sodium nitrite and analyzed using ion chromatography (Koutrakis et al., 1993). Measurements of NO2 involved passive sampling on filter paper impregnated with the solution of triethanolamine and acetone in the ratio 1:1. After extraction from the filters, concentration of NO2 was determined spectrophotometrically (UNEP/WHO, 1994). In addition to standard descriptive statistics, the data were analyzed using bivariate functional principal component analysis (Ramsey and Silverman, 1997). Smooth periodic functions were fitted to data on O3 and NO2 concentrations for each site, assuming the period of one year. Typical temporal variation in O3 concentrations showed high summer and low winter concentrations. Concentrations of NO2 did not show such obvious seasonal variation. Functions were represented using 7 principal Fourier basis functions. The first two bivariate principal component (PCA) functions accounted for 96.1% of variability. The solid curve represents mean concentration and + (-) represents the effect of adding (subtracting) a principal component. The first PCA function accounted for 74.3% of variability. It corresponded to a time shift in the onset of the summer peak for O3 and overall level of NO2 concentrations emphasizing the spring/summer period. Sites with positive score on this function had earlier O3 peaks and higher NO2 concentrations (especially during spring/summer). The second PCA function accounted for 21.8% of variability. It corresponded to the level of the summer peak for O3 and overall level of autumn/winter NO2 concentrations. The Center's high score on the first PCA function indicates its early onset of the O3 peak and high overall NO2 concentrations. The North had the lowest score on this PCA function. The Center's high score on the second PCA function reveals its high concentrations of O3 in the summer and of NO2 in the autumn/winter. The West and the South had the lowest scores on this function, while the North was more similar to the Center. The proximity of the West and the South indicates the similarity of their patterns of annual variation.

Izvorni jezik
Engleski

Znanstvena područja
Javno zdravstvo i zdravstvena zaštita

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