engleski

Heavy metals in the soil of the Varaždin region (Croatia)

Heavy metals are naturally present in soil up to certain levels as a consequence of the soil’s mineral content. However, above certain levels, the presence of heavy metals is a consequence of pollution. The most common sources of pollution are: traffic, fossil fuel consumption, mineral fertilizers, pesticides, floods, landfills etc. Heavy metals cannot be degraded ; they accumulate in the soil or sediment of water ecosystems. So they get into the food chain, and in elevated concentrations have a toxic influence on humans and other living organisms. The aim of this work was to determine the concentration of heavy metals in the soil of regularly-mown green city areas in the Varaždin region, in order to find possible heavy-metal pollution, and to detect the types of metal which exceed prescribed levels. Samples were collected from the upper layer of the soil, up to 15 cm in depth, at 16 locations during June and July of 2013. The concentration of heavy metals was determined by using atomic absorption spectroscopy. The levels of the following metals were determined: cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). Pollution was estimated on the basis of the Ordinance on the Protection of Agricultural Land Against Pollution (OG 09/14), since at the moment it is the only legislative document in the Republic of Croatia that prescribes the maximum allowed concentrations of heavy metals in soil. The results obtained have shown that eight locations were contaminated with heavy metals. Excess amounts of Pb were observed at seven locations, of Cd and Zn at three locations, of Ni at two locations and of Cu at one location. The three most contaminated locations were: the railway station in Varaždin (maximum allowed concentrations of Cd, Cu, Ni, Pb and Zn exceeded), Dravski otok (maximum allowed concentrations of Cd, Pb and Zn exceeded) and Svilarska ulica (maximum allowed concentrations of Cd, Pb and Zn exceeded). The most likely cause of pollution at the railway station was railway traffic ; at Dravski otok, flooding of the River Drava ; and in Svilarska ulica, the vicinity of the VIS factory plant. Contrary to expectations, at locations by crossroads and roads with heavy traffic, either there was no observation of increased concentrations of heavy metals or, in some cases, a slight excess of Pb was detected, which can be attributed to pollution by road traffic.

green city areas; heavy metals; pollution; soil; Varaždin

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