THE ORIGIN OF ARSENIC IN SOILS AND GROUNDWATER OF THE PANNONIAN PART OF CROATIA

Sa？etak Arsenic content in surface layer (0-25 cm) varies from 0.9 mg/kg soil to almost implausible 490 mg/kg. The reason for the highest content in hydromorphic soils should probably be sought in recent history. It is less probable that the reason for the increased arsenic content in hydromorphic soils is the geological origin of rocks in river valleys. It is more probable that the reason for the increased arsenic content is river flooding and changes in river flows in the recent past. Based on 208 groundwater samples from 12 locations of Koprivnica-kri？evci county during 2009-2012, the range of arsenic concentration from <0.1 μg/l to 25.4 μg/l was determined. The concentrations are, generally, very low (<0.1-6.9 μg/l) on the most of locations. The values in Vratno and Kolarec locations indicate an increase in arsenic concentration above the permitted values. Groundwater that is rich with arsenic is result of the natural mineral weathering of rocks