engleski

DEPOSITION OF ACIDIC COMPONENTS AND HEAVY METALS IN ZAGREB IN 1999-2001

Monthly samples of atmospheric depositions were collected over three years (1999-2001) at five different sites (city centre, northern, southern, western and eastern part of the city) in Zagreb using a Bergerhoff-type deposit gauge. After determining the total deposition, the samples were analysed for acidifying ions (Cl-, NO3-, SO42-) and heavy metals (Pb, Cd, Tl). Over the three years, total deposition varied from 18 to 518 mg/(m2d), chloride content from 0 to 20.42 mg/(m2d), nitrate from 0 to 10.66 mg/(m2d) and sulphate from 1.00 to 20.24 mg/(m2d). Lead varied from 9 to 93 &micro ; g/m2d, cadmium from 0.13 to 13.72 &micro ; g/m2d and thallium from 0 to 12.86 &micro ; g/m2d. No correlation between acidifying ion and heavy metal content has been found. It is assumed that the deposition includes other components, such as sodium, potassium, calcium, ammonia etc., which were not measured. Croatian legislation (Ordinance, 1996) defines recommended and limit values for monthly lead, cadmium, and thallium content in deposited matter. Lead and cadmium content in deposited matter were below the recommended values at all five sampling sites. Thallium content was above the recommended value, but under the limit value at four sampling sites, and below the recommended value at one sampling site (eastern part of the city).

Acidifying ions; Heavy metals; Total deposited matter; Recommended value; Limit value

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