Air pollution studies in the city of Zagreb I. analysis of deposited matter

U toku godine dana sakupljani su i analizirani mjesečni uzorci sedimenata na 11 mjernih mjesta na području grada Zagreba. Rezultati su analizirani s obzirom na kretanje stupnja onečišćenja atmosfere u toku godine, i s obzirom na prostornu raspodjelu sedimenta na području grada Zagreba. Usporedba rezultata s podacima o onečišćenju drugih evropskih gradova pokazala je da se Zagreb, po stupnju onečišćenja atmosfere, nalazi među industrijskim gradovima s vrlo nečistom atmosferom.In the course of a year (April 1. l 9fi2 - March 31, 1963) monthly samples of deposited matter at eleven sites in the territory of Zagreb were collected and analysed. The results have shown that there was no regularity in the changes of the air pollution level in the course of the year, but that there was a relationship between·the amount of deposited matter and the amount of precipitation; this relationship was found proportional for soluble and inversely proportional far insoluble matter. This indicates the local character of the insoluble and gaseous origine of the soluble matter. The amount of tarry matter found in residential parts of the town was conspicuously higher in winter than in summer, while in industrial parts the difference was not statistically significant. Sulphates were found in considerably greater amounts in industrial than in residential areas all the year round, while in all areas their amount was significantly higher in winter than in summer. Sulphates in the atmosphere obviously originate from gaseous S02 produced by fuel combustion. The same applies to tarry substances, only that they are the result of incomplete fuel combustion which is more frequent in household heating of residential areas. Spatial distribution of the deposited matter shows two maxima: one in the eastern and one in the western industrial part of the town. By prevailing wind (N-NE) air pollutants are spread toward the south-western periphery of the town, with the exception of May and October when the north-western wind prevails and spreads pollutants from the western to the central parts of the town. In comparison with data on other European towns, Zagreb appears to be, with regard to the degree of its atmospheric pollution, among industrial towns with heavy air pollution. The problem calls for further more detailed studies