engleski

ATMOSPHERIC PARTICULATE MATTER LEVELS IN PLITVICE LAKES NATIONAL PARK DURING SUMMER AND FALL

We investigated the impact of meteorological conditions and number of visitors on the atmospheric particulate matter (PM) mass concentrations and particle fraction ratios at the Plitvice Lakes National Park during summer and fall of 2018. Outdoor concentrations of particles with an aerodynamic diameters less than 1 µm, 2.5 µm and 10 µm (PM1, PM2.5, and PM10, respectively) were measured by a light- scattering laser photometer. The photometer was placed at the meteorological measuring site for which concurrent meteorological data were available. Another photometer recorded only the PM1 fraction in the nearby office of the National Park. Apart from standard statistical methods, the Openair software, which was developed specifically for the analysis of air quality data, and spectral analysis based on weighted overlapped segment averaging (WOSA) method were applied. Results showed an increase in mass concentration with the increase of number of visitors and the air temperature for all measured PM fractions. The latter, together with the decrease of PM1/PM2.5 ratio with an increase of temperature, pointed to the importance of photochemical reactions in the production and growth of particles. Furthermore, outdoor PM concentrations and PM1/PM2.5 and PM2.5/PM10 ratios decreased as the wind speed increased. As seen from bivariate polar plots, the highest and the lowest PM1/PM2.5 and PM2.5/PM10 ratios were associated with winds from the north-western and south-eastern quadrant, respectively. Apart from the diurnal periodicity of both PM and meteorological time series, a period of ≈ 25 min was present in the PM10 spectrum. This period was very likely associated with particle emissions and resuspensions due to diesel- powered tourist vehicles. While weekly periodicity was present in average weekly courses of all fractions of particulate matter, it was not accompanied by expected peaks in the PM spectra.

PM10, PM2.5, PM1, laser photometer, Openair, WOSA method

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