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HARMFUL HEAVY METALS IN FOREST SOIL AND FRUIT GROWING IN ENVIRONMENTALLY LOADED REGION OF SLOVAKIA

Alena Vollmannová

Abstract

The Upper Orava region is for several decades affected by emissions from manufacturers of ferroalloys as well as by a transport of pollutants via the atmosphere from abroad. The aim of this study was to assess the degree of risk for Pb, Cd, Cr, Cu, Zn, Ni and Co input from soil into small forest fruit species growing in this region. Soil and fruit samples were collected from 8 sampling points exactly fixed using GPS. In soil the agrochemical characteristics (pH/KCl, content of K, Mg, P, Ca and humus) were determined. Pseudototal content of heavy metals including all metal forms except of residual fraction was determined in soil extract by aqua regia and the content of bioavailable forms in soil extract by NH4NO3 (c = 1mol/L) using the flame AAS method and compared to hygienic limits for agricultural soils. The contents of risky metals in fresh fruits as well as in dry leaves of blueberries and raspberries were determined by AAS method, too. Obtained results were evaluated according to legislation valid in the Slovak Republic. In all sampling sites the determined pseudototal soil Cd content (2.48-2.95 mg/kg) as well as content of mobile Pb and Cd forms (0.18 ? 0.79 and 0.11 ? 0.43 mg/kg, resp.) were higher than limit values. Content of bioavailable Zn forms (0.47 ? 11.26 mg/kg) exceeded in 5 soil samples the critical value given by the legislation. In all fruit samples the determined Pb and Cd contents (1.18 ? 1.80 and 0.12 ? 0.19 mg/kg, resp.) were higher than hygienic limits and in 4 fruit samples also content of Ni (0.38 ? 1.00 mg/kg) exceeded the maximal allowed amount. At the same time, in dry leaves of all fruit species the determined values of Pb, Cd and also Ni content were higher than hygienic limits. The intervals of determined values of Pb, Cd and Ni content (mg/kg) in leaves were: 3.63 ? 10.60; 0.94 ? 1.49 and 2.01 ? 4.80. Our results suggest the casual connection among enhanced contents of dangerous heavy metals in soils as well as forest fruit growing in the vicinity of emission sources and the metallurgical activity in this area.

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