Effects of topography on caesium-137 in montane peat soils and vegetation

Abstract

This study investigated the relationship between altitude and ¹³⁷Cs fallout in soils and plants. The soils and plants, Calluna vulgaris, Erica cinerea and Molinia caerulea, were sampled across a transect of two valleys in north-western Ireland. The results provided evidence that greater ¹³⁷Cs deposition to soils occurred at higher altitudes, and the data supported the findings of a previous investigation in the same area. A valley effect, whereby greater concentrations of ¹³⁷Cs accumulated in plants on the lower altitudes of the valley floors, was shown to be significant. Deposition values for total ¹³⁷Cs in soils were not correlated with plant concentrations, although a relationship between concentrations in C. vulgaris and M. caerulea was found to be statistically significant. No relationship was observed between the ¹³⁷Cs from weapons fallout with that of Chernobyl origin in the 0–10 cm depth soils, although a significant correlation emerged between the same two components measured in C. vulgaris. The results suggest that existing definitions of concentration ratios and transfer factors are, for many reasons, inappropriate for studies of soil to plant transfer of ¹³⁷Cs in peatland ecosystems.