Air pollution - State and impacts (Croatia)
- Air pollution
Figure 4. Spatial distribution of mean annual concentrations (mg/l) in precipitation and mean annual deposition (kg/ha) of sulphate ions (SO ), nitrate (NO ) and ammonia (NH ), 2005-2008.
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Air quality in settlements
Air quality is monitored in settlements and cities or their parts where a more significant pollution occurs. In rural areas the air is generally clean, and pollution is transported there from polluted urban or industrial areas.
Clean or slightly polluted air (first category air) was recorded in 60 % of cities and settlements or their parts in Croatia in the period from 2005 to 2008 . Moderately polluted air, or second category air, was recorded in 20 % of cities and settlements or their parts, while excessively polluted air, or third category air, was also recorded in 20 % of cities and settlements or their parts.
The pollutants which excessively or moderately contaminate the air include sulphur dioxide, nitrogen dioxide, total suspended particulate matter, suspended particulate matter with aerodynamic diameter less than 10 µm (PM10), suspended particles with aerodynamic diameter less than 2.5 µm (PM2.5), benzo-a-pyrene in PM10, hydrogen sulphide, ozone, benzene, ammonia, total deposited matter, lead, nickel, cadmium and thallium in total deposited matter.
Atmospheric pollution of particulate matter with aerodynamic diameter less than 10 µm (PM10) is the most widespread problem in Croatia. The particles primarily come from traffic, large combustion plants and large point sources (Figure 1).
Targeted measurements of hydrogen sulphide (H2S) are done in Rijeka, Kutina and Sisak. The air quality was of second and third category due to too many exceedances of hourly concentration of limit values and margins of tolerance. Mean annual concentrations were mainly below the allowable limit value (Figure 2).
Air pollution with ammonia (NH3) has been reduced in Croatia (Figure 3).
Tropospheric ozone is the key ingredient of so-called summer smog, the main pollution problem in almost all big cities worldwide. In Zagreb and Rijeka agglomerations, air quality with respect to ozone was of second and third category respectively. The ground-level ozone is the most important photochemical oxidising agents in troposphere. It is a secondary pollutant since it is not emitted directly, but generated by photochemical reactions (with solar irradiation) from nitrogen oxide and volatile organic compounds which comprise the urban atmosphere.
Acidification and eutrophication
The spatial distribution of mean annual concentrations (mg/l) and mean annual deposition (kg/ha) of sulphate, nitrate and ammonia is shown in Figure 4. Precipitation pollution by sulphates is the most prominent in Osijek, eastern Croatia, and in areas with increased SO2 emissions (City of Rijeka area).
Ammonia concentrations in the region of Slavonia, eastern Croatia, are twice the national average. Significant sources of ammonia emissions are agriculture and animal husbandry, which are dominant in the eastern Croatia (Slavonia) region. Transboundary air pollution movement from neighbouring countries, particularly from Serbia and Hungary considerably contributes to increasing values acidification and eutrophication compounds in the area of eastern Croatia.
The largest deposition of acidification and eutrophication compounds is recorded around the City of Rijeka and in Gorski Kotar region, and in eastern Croatia. Although ammonia concentrations in precipitation are greatest in eastern Croatia, the highest level of deposition has been recorded in Gorski Kotar, which is due to increased precipitation rates in this area. Climate in areas with particularly high levels of deposition is characterised by increased precipitation, but there is also an important contribution of local sources of sulphate, especially in the area of the City of Rijeka.