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The Sahara is the world’s largest source of the aeolian desert dust. The dust can be entrained over large areas in dust storms, transported over thousands of kilometers and then deposited downwind. Saharan dust has a major influence on soil characteristics, oceanic productivity, air chemistry and climate. Most Saharan dust is deposited from the atmosphere over Mediterranean countries of southern Europe by dry or wet deposition. Here, the characteristics of Saharan dust episodes over part of the southern Europe (Croatia) will be shown. We tried to determine the frequency of mud rains over Croatia and investigated their influence on precipitation chemistry. Further on, we analyzed the influence of Saharan dust on the coarse fraction levels (PM10) at several measurement sites in Croatia. Saharan dust episodes were identified using satellite data and backward trajectories. In addition, synoptic situations prevailing during the investigated Saharan episodes were analyzed. Three main types of weather situations connected to the transport of the dust from Sahara desert to Croatia were revealed and their characteristics will be shown.

This study investigates the influence of weather types found over the continental part of Croatia on daily PM10 concentrations and concentrations of metallic compounds in PM10 (namely manganese, lead and cadmium) in air during 2000-2002 period. Pollutant concentrations were measured at the northern, residential part of Zagreb, far from the major pollution sources. Weather types were determined from synoptic charts. In the employed categorization six different patterns were recognized: radiation weather type, high pressure ridge, precipitation weather type, southeastern advection, northeastern advection and wind weather type. The most frequently, elevated concentrations were related to radiation weather type and southeastern advection, while the lowest concentrations were recorded during the wind weather type. Obtained results generally suggest a major role of the local pollution sources, and particularly of the Zagreb industrial zone, in suspended particles/metallic compounds pollution. Since cadmium exhibits somewhat different behavior, the role of the long-range transport in cadmium pollution needs to be further investigated. Synoptic conditions favorable for elevated concentrations occurred in about 37 % of investigated days. Typically, these conditions are characterized by 1) the weak winds and turbulence, and consequently, inefficient pollutant concentration dilution (the nighttime and wintertime radiative conditions) ; or 2) southeastern airflow (southeastern advection and daytime radiative conditions), which transports pollutants from industrial zone of Zagreb towards the measuring site. Due to the latter, particulate pollutants emitted in the industrial zone pass rather frequently above the eastern part of Zagreb.

Particulate matter (PM10 particle fraction) and trace gases (CO, NO and NO2) have been sampled during six weeks in the Tuhobić road tunnel, Croatia, whose length is 2140 m. Eight mini portable air samplers (Air Metrics, USA) were placed in the centre of the tunnel at a height of 1.70-m above the ground. PM10 samples were collected on Whatman quartz filters with the diameter of 47 mm, while gases were collected in Tedlar bags. Diurnal variations of pollutant concentrations for weekends and weekdays were determined based on cumulative eight- and four-hour sampling intervals, respectively. Results revealed the dependence of air pollution levels on both, the traffic density and pollution history, i.e., traffic density in times prior to the time interval concerned. The highest correlation between PM10 and trace gases concentrations was found for NO2, while among the trace gases NO and CO were the best correlated.

U ovom radu prikazan je utjecaj tipova vremena na koncentracije frakcija lebdećih čestica PM10 i PM2.5. Uzorci su sakupljani na filtre od staklenih vlakana Whatman EPM 2000 promjera 47 mm. Sakupljanje je provedeno u dvorištu Instituta za medicinska istraživanja i medicinu rada, u rezidencijalnom dijelu grada Zagreba u razdoblju od 1.8.1999. do 31.7.2002. godine. U radu je korištena klasifikacija tipova vremena po Poju. Grupacija tipova vremena u šest grupa pokazuje značajne razlike u koncentracijama lebdećih čestica po tipovima vremena. Tipovi vremena stabilnih vremenskih prilika s visokim tlakom, slabim vjetrom, kao i s temperaturnim inverzijama duljeg trajanja, obilježeni su višim koncentracijama lebdećih čestica. S druge strane, niže koncentracije lebdećih čestica javljaju se pri izraženom vjetru, oborini i pri hladnoj advekciji tijekom toplog dijela godine.