Cesium-137 Concentrations in Sediments and Aquatic Plants from the Pinios River, Thessalia (Central Greece)

The levels of radioactive contamination by artificial radiocesium (¹³⁷Cs) were evaluated in sediments and the commonest species of water plants. Specimens were collected from a range of biotopes along the Pinios River and its tributaries, during the years 1998 and 2010. The ¹³⁷Cs concentrations within the above period clearly indicate that this radionuclide still decrease in the River Pinios. A marked decrease is also observed in comparison to our previous results in 1993. ¹³⁷Cs concentration activities in the sediment are higher than in the plant material. In general, roots showed greater ¹³⁷Cs concentration than leaves, while stems showed the lowest concentration. Significant differences in ¹³⁷Cs concentrations were found among different species growing under similar environmental conditions. ¹³⁷Cs content in collected aquatic plants was in the descending order: Ceratophyllum demersum L. > Myriophyllum spicatum L. > Paspalum pasalodes Scribner > Cladophora glomerata L. > Cyperus longus L. > Potamogeton nodosus Poiret. A comparison of the studied stations indicated that the southwest side of Thessalia plain, where the first two initial sampling stations of the Pinios River and the tributaries Enipeas and Kalentzis are situated, was highly contaminated. Low ¹³⁷Cs concentrations were observed in the Titarisios tributary, originated from the northeast part of Thessalia plain, behind Mt. Olympus and the last sampling stations of the Pinios River.