engleski

Airborne Ammonia and Ammonium in the Northern Adriatic Area (Croatia)

Determination of airborne ammonia started in early eighties, as a part of air pollution monitoring programme in the proximity of industrial plants: old petroleum refinery facilities located in the wider city center (Site 1) and in the proximity of the new industrial area eastwards from the city (Site 2) where new petroleum refinery, power plant and coke plant were erected. Due to high emissions from these industrial plants, the city of Rijeka was one of the most polluted in Croatia in mid-eighties. Post-war reduction in industrial activity, switch to use of better quality fuel and better maintenance of industrial facilities resulted in considerable reductions in SO2 and NOx emissions (approx. 70% and 40%, respectively) that led to lower airborne levels of these pollutants. In spite of coke plant closure in 1994, there is only weak decline in airborne ammonia over a period of 25 years (1980-2005), with annual means being in the range of 12-20 μ g/m3 at Site 1 and 6-28 μ g/m3 at Site 2. Similar behaviour is observed with ammonium in bulk rainwater samples since 1996, if data for 2002. were excluded because of higher frequency of Saharan sand episodes. Though without any significant point source, ammonium’ s contribution to total nitrogen deposition is approx. 2/3. As with PWA of nitrate, higher concentrations (45-70 μ M) of ammonium were found only at Site 1, thus confirming the local wash-out of the atmosphere, while at Site 3 (remote island in the Kvarner Bay) these concentrations were lower (30-40 μ M).The PWA concentration of ammonium at Site 4 are between these two levbels. The lower deposition of N-NH4 was observed at the remote Site 3 (approx 300– 400 eq/ha y) , while higher values were obtained for the urban Site 1 and the remote mountainous Site 4 (approx 330-870 eq/ha y, up to 1660 eq/ha y in 2002 ).

atmosphere; ammonia; ammonium; Northern Adriatic

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