Assessing the present levels of 137Cs in the remote ecosystem of Bjornoya (South Svalbard)

Abstract

The remoteness and small size of Bjornoya (S Svalbard) make the island one of the most unreachable places in the Arctic. Limited accessibility contributes to still-existing knowledge gap on isotope accumulation in compartments of its ecosystem. Therefore, in this study we aimed to investigate the current concentration of ¹³⁷Cs in the terrestrial samples of vascular plants, cryptogams, and soil collected on Bjornoya in 2021. The measured average activity of ¹³⁷Cs in bryophytes was 56.5 Bq kg^-1, lichens 27.6 Bq kg^-1, vascular plants 7.26 Bq kg^-1, and soil 9.63 Bq kg^-1. In the case of bryophytes, ¹³⁷Cs activity was negatively correlated with δ¹⁵N. Our results suggest that bird guano was the main source of nitrogen and ¹³⁷Cs for vascular plants. For bryophytes, significantly lower values of δ¹⁵N than in vascular plants suggests that this group is more sensitive to atmospheric N intake, with fallout being the main source of ¹³⁷Cs.

Keywords: Bioaccumulation; Cryptogams; Isotope; Monitoring; Radioisotope; Vascular plants.