engleski

Porijeklo arsena u tlima Panonskog dijela Hrvatske

In order to determine the origin of arsenic in soils in the Pannonian part of Croatia data were collected from the agro-ecological studies that the Department of General Agronomy, Faculty of Agriculture, conducted in the period from 1989 to 2015. In this period more than 1, 000 soil samples were collected from the surface layer (0-25 cm), and about 100-odd samples from a depth of 100 cm. In order to determine the origin of arsenic, research results are presented according to soil origin - automorphic and hydromorphic soils, and soil use - agricultural, forest and technosols. Arsenic content in surface layer (0-25 cm) varies from 0.9 mg/kg soil to almost implausible 490 mg/kg. In automorphic soils that develop without excessive retention of precipitation or groundwater average arsenic content was 10.7 mg/kg, and the maximum content was 31 mg/kg. In hydromorphic soils that are formed under the influence of surface and groundwater, which are in the area closest to the riverbed of the Drava River (where the majority of samples were taken) average arsenic content was 14.8 mg/kg, and the maximum content was 490 mg/kg. In soils covered with forest vegetation average arsenic content was 13.9 mg/kg while the maximum content was 267 mg/kg. In technosols (most of these are soils from which petroleum hydrocarbons are extracted) average arsenic content was 14.4 mg/kg, and the maximum content was 143 mg/kg. In terms of vertical distribution of arsenic (in different depths of soil) the content is uniform in automorphic soils, while large profile deviations were recorded in hydromorphic soils. On the basis of the conducted research it can be concluded that current anthropogenic activities (agriculture and extraction of hydrocarbons) have not caused an increase of the arsenic content in soils of the Pannonian part of Croatia. The reason for the highest content in vertical and horizontal distribution in hydromorphic soils should probably be sought in recent history. It is less probable that the reason for the increased arsenic content in hydromorphic low-ground 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. It is widely known that in the first half of the last century, the impure waters from factory areas were discharged during the periods of high water levels. At that time there were no defensive embankments and during the floods the water would spread across flooded areas. More precise results should be obtained by more detailed vertical and horizontal soil sampling, and sampling on both sides of the Drava River.

arsenic; type of soil; land use

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