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THE IMPACT OF AGRICULTURE ON THE CAMBISOL SOIL DEVELOPED IN THE AREA OF THE VELIKA GORICA WELL FIELD

Increased concentrations of anions and cations, as well as potentially toxic metals in the agricultural soils developed in the area of water field Velika Gorica can present problem from the standpoint of environmental risk. The subject of this study is the Cambisol soil developed on the area of the Velika Gorica water well field. The objective of this research was to determine the main soil properties and soil accumulation or mobilisation of potentially toxic metals and ions in Cambisol under agricultural activities. Physical, mineralogical and geochemical analysis of the collected soils were carried out in order to determine their properties, such as soil reaction (pH), electrical conductivity, carbonate, organic and mineralogical content and grain size distribution. Sequential extraction analysis was made to determine the main binding site of potentially toxic metals in the soil. The analyses were performed according to the BCR procedure and proportions of elements were determined in four fractions: (1) carbonate, (2) the fraction of Fe-Mn oxide and hydroxide, (3) organic-sulphide, and (4) residual fraction. The following potentially toxic metals were measured: Cu, Cd, Zn and Pb. The analysis of anions and cations (Na+, K+, NH4 +, Mg2+, Ca2+, Cl-, NO3 -, NO2 - and SO4 2-) were made using ionic chromatography. The analysis showed that the concentrations of potentially toxic elements (Cu, Cd, Zn and Pb) as well as cations and anions (Na+, K+, NH4 +, Mg2+, Ca2+, Cl-, NO3 -, NO2 - and SO4 2-) are significant in a layer of up to about 80 cm. Their concentration decreases beneath the specified depth as a result of particle size distribution, dominated by silt and clay that determine a lower permeability of the soil. Surface samples showed increased element concentrations, as well as the influence of agricultural activities. Even though influence of agricultural activities is recognized, all results show that impact is decreasing after approximately 80 cm depth.

agricultural activities, unsaturated zone, potentially toxic metals, cations and anions, Cambisol

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