Possible Influence of Agriculture on an Unsaturated Zone in Croatia

摘要

Soil contamination in the agricultural areas developed on open aquifer systems can be environmental problem. The subject of this study is the Cambisol soil developed in the area of the Velika Gorica well field. The aim of this research was to determine possible agricultural influence on the unsaturated zone of the Zagreb aquifer area where Cambisol soil is developed. Concentrations of potentially toxic metals (Cu, Cd and Zn) and major cations and anions (Na+, K+, NH4+, Mg2+, Ca2+, Cl-, NO3-, and SO42-) were determined in soil horizons. Correlations between physical and chemical soil properties, analysed ions and potentially toxic metals were made. Samples that were closer to the surface showed increased element concentrations, indicating the increased impact of agricultural activities in the research area. All analysed potentially toxic metals showed highest concentrations in residual fraction, which indicates the possible influence of agricultural activities such as usage of fertilizers, manure, sludge as soil fertilizer and fungicides, or point sources of contamination, uncontrolled, active or untended waste dumps and aerodeposition. Statistical analysis showed strong correlations between the concentrations of the studied potentially toxic metals and some soil properties such as soil texture, pH and organic matter. In addition, correlation results between nitrates and some potentially toxic metals such as Cu and Zn indicate that these elements come from the same source of contamination, in this case probably agricultural activity. Even though the influence of agricultural activities is recognized, all results show that the impact is decreasing after approximately 0.8 m depth.