Search for latitudinal trends in the effective half-life of fallout ¹³⁷Cs in vegetation of the Canadian Arctic

Abstract

Using published data on the integrated deposition of fallout 90Sr (137Cs) until 1975 and current measurements of the,137Cs activity in plant communities along the latitudinal gradient north of 50° N, an estimate has been made of the 137Cs effective half-life, Teff, in the composite vegetation of the Canadian Arctic. The lichens Alectoria nigricans, Alectoria ochroleuca, Cladonia rangiferina, Cornicularia divergens, and Umbilicaria muhlenbergii were studied, as well as a moss, Polytrichum juniperinum, and the vascular cushion plants Dryas integrifolia, Saxifraga oppositifolia, and Silene acaulis. In all cases, the effective half-life increased with increasing latitude, the longest Teff (10–12 years) being exhibited by dry-habitat lichens at 80° N.

Cesium-137 monitoring using lichens and mosses from northern Greece

“…Their high surface area to biomass ratio, the absence of cuticle on the thallus surface, and the slow growth rate combine to enhance the interception and retention of 137Cs from fallout (Svoboda and Taylor 1979;Taylor et al 1985;Eckl et al 1986;Papastefanou et al 1989). The dense canopy of mosses also acts as an efficient filter in trapping airborne particles.…”

Bioconcentration of Fallout 137Cs by Fungi and Red-backed Voles (Clethrionomys gapperi)

“…Lichens and mosses are known to accumulate 137Cs originating from atmospheric contamination, because of their complex surfaces (Looney et al 1986). Loss of 'j7Cs is extremely slow, with effective halflives of 10+ y for lichens and 4 y for mosses (Mattsson and LidCn 1975;Taylor et al 1985). In contrast, high concentrations of 137Cs in the Ericaceae are thought to be related to this family's association with mycorrhizal fungi on acidic soils typical of bogs (Bunzl and Kracke 1986).…”

Issues and Challenges in Assessing Ecological and Human Health Risk From the Siting of SMRS in Canada

“…Canadian Nuclear Laboratories (CNL) are actively pursuing a SMR demonstration project on the Chalk River site, with a 2026 target date for operation. The Chalk River site, with a long history of nuclear reactor operation, environmental research, and assessment (see e.g., [1][2][3]), poses fewer challenges from an ecological and human health risk assessment perspective than more remote, northern, or Arctic regions, where current knowledge of radioecology is rudimentary [4][5][6]. Significant data and knowledge gaps remain and need to be filled to develop parameters and models to accurately assess risk to these remote regions, where communities often depend on hunting and fishing for a considerable portion of their diet [7,8].…”