Bioaccumulation of polonium (²¹⁰Po) and uranium (²³⁴U, ²³⁸U) in plants around phosphogypsum waste heap in Wiślinka (northern Poland)

Abstract

In the study the activities of polonium ²¹⁰Po and uranium ²³⁴U, ²³⁸U in plants, collected near phosphogypsum waste heap in Wiślinka (northern Poland), were determined by using the alpha spectrometry. The obtained results revealed that the concentrations of ²¹⁰Po, ²³⁴U, and ²³⁸U in the analyzed plants were differentiated. In the analyzed flora organisms the highest amounts of polonium and uranium were found in ruderal plant samples as well as willow samples (Salix viminalis) from protection zone of phosphogypsum waste heap. The concentrations of ²¹⁰Po, ²³⁴U and ²³⁸U in the analyzed plants were higher in roots than in green parts of plants. The higher concentrations of ²¹⁰Po and ²³⁸U radionuclides were estimated for hydrophyte (common sedge Carex nigra Reichard), the favourite habitat of which is particularly wet meadow and for plants co llected in the vicinity of phosphogypsum waste heap. The major source of polonium and uranium in analyzed plants is root system. The values of ²³⁴U/ ²³⁸U activity ratio in all analyzed plants are closed to one, what indicated that source of uranium in analyzed plants is phoosphogypsum. The highest uranium and polonium concentrations were characterized for plants, which are covered with tomentose.

The comparability polonium and uranium contents were confirmed in edible plants, but higher accumulation was determined in ripe species than immature species of vegetables. The higher polonium and uranium concentrations were noticed in green parts of plant, the lower in roots. Polonium concentration in cultivated plants samples was not species diverse. Therefore, the significant source of polonium and uranium in analyzed plants is wet and dry atmospheric falls gathering the soil and air dust from phosphogypsum waste dump.

The maximum ²¹⁰Po and ²³⁸U radionuclides concentrations were found in green parts of red beet (Beta vulgaris esculenta), the minimum in garden radish (Raphanus radicula). That's interesting too, that both species have hypocotyls tubers, but tuber of red beet is large than garden radish. In our opinion these differences may be connected with turgidity because leaves and root of radish garden were withered.