Heavy Metal Concentrations in Some
Slovakian Agricultural Soils

Salem Yaseen Mejeed Department of Geochemistry, Faculty of Natural Sciences, Comenius University,
Mlynská dolina, 842 15 Bratislava, Slovakia


In excess quantities many of the trace elements present in soils may be toxic to plants and/or animals or may affect the quality of foodstuffs for human consumption. In Slovakia, there are many evidences that human health is under stress of such geochemial factors in many districts. Consequently, high attention is being paid currently to follow concentrations of trace elements in agricultural soils. We present here our current results from agricultural soils in the south- western part of Slovakia (Z˜itny´ ostrov region), hopping to present results in the proposed poster session from agricultural soils of the Malé Karpaty Mountains (Small Carpathians) situated to the north-west of the first region, which is very important from the anthropogenic viewpoint because, historically, it was under the stress of mining and smelting activities for long periods.

The area of Z˜itny´ ostrov is economically very important for the country as it is agriculturally very densely and diversely exploited. In the same time it is considered to be the largest aquifer in Central Europe potentially used for drinking, domestic and irrigation purposes which is in danger of agricultural and industrial pollution due to the very shallow groundwater level.

Trace element contents in these soils are in good consistency with those of the normal range in soils, of the mean sediments and of the earth crust. Therefore, they could be considered to represent the natural backgroud levels in the studied soils, with only few exceptions of enhancement or depletion that could be attributed to both natural and man-induced activities.

Comparison of the vertical trends of trace elements and other studied properties along the soil profiles showed a close relations among the trends of most trace elements (decreasing downwards) and the trends of clay fraction and organic carbon, being concentrated in the surface horizons (biogeochemical barriers) and depleted in the lower horizons, which is also expressed by similar trend for CEC. While sand fraction shows a contrary trend. Carbonate showed an increase with depth in line with Sr trend and pH (evaporative carbonatic geochemical barriers). In addition to Sr, elements Ag, As and Cd showed an increasing trend downward the soil profile. These observations were also proved by calculating the correlation coefficients among the trace elements and the different soil properties. Most of these elements displayed positively significant correlation coefficients with the clay and the organic carbon, Zr with the sand fraction and Sr with carbonate. Elements Ag, As and Cd did not show any significant relation to the studied fractions and therefore are supposed to be most probably associated with the Fe and Mn oxides (oxidizing geochemical barriers).
Such occurrences are also reflected in the inter-elements correlation patterns.

Comparison of total trace element contents with Dutch standards for the assessment of any anthropogenic influence revealed the existence of only limited contamination on a local scale in case of the elements Ag, As, Cu, Hg and Ni. Elements Ba, Be, Cd and V exceed the allowed limits in most of the studied samples, however, their enhanced values could be mostly attributed to the parent material, with the exception of Cd which could be partially of anthropogenic origin due to application of fertilizers.