The latitudinal inventory of ¹³⁷Cs in vegetation and topsoil in northern Canada, 1980

Abstract

The latitudinal distribution of fallout 137Cs in Canada has been determined along a transect extending from 50° to 82° N in 1980. The 137Cs content of lichens, bryophytes, and cushionlike vascular species was measured at 16 sites between Brandon, Manitoba, and Alert, Ellesmere Island. Lichen species were shown to be the most effective biological monitors of 137Cs deposition because of their specific morphology, longevity, and slow growth rates. Dry, exposed ridges were the sites of the highest 137Cs retention by plants. 137Cs levels in vegetation followed a bell-shaped distribution along the transect and the maximum accumulation was measured in samples collected between 60° and 70° N (10 nCi m−2 at 63° N) (1 Ci = 37 GBq). This distribution is the combined result of the original latitudinal deposition of 137Cs, the expired portion of its physical half-life, and the efficiency of biotic and abiotic removal processes along the studied corridor. It is suggested that the long-term implications of 137Cs in the northern food chain ought to be followed and studied more closely in the light of the data presented.

Elevated PCB Contamination of Coastal Plants Near Polynyas in the High Arctic

“…This is important because accumulation of cesium has been shown to be reduced for arctic vegetation collected from such mesic sites (e.g. Hutchison-Benson et al 1985) presumably as a result of the protective cover of snow. Because PCB uptake by plants proceeds through foliar assimilation due to atmospheric transfer rather than by root relocation, it may be inferred that the higher snow associated with polynyas could likewise produce lower toxicant residues in plants growing there.…”

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

“…Cesium-134 was detected in many samples of vegetation, and it should have decayed below its detection limit since the time of nuclear weapons testing (Persson 1968). Similarly, unusual radionuclides such as IMRu and 12%b were detected in epiphytic lichens, known accumulators of atmospheric contaminants (Eckl et al 1984;Hutchison-Benson et al 1985;Eckl et al 1986;Looney et al 1986). These results agree with the trace levels of Chernobyl radionuclides found by others in southern Ontario in the spring of 1986 (Joshi 1987).…”

Cautionary notes on the assumptions made in erosion studies using fallout 137Cs as a marker

“…Significant quantities of 137 Cs have been found in soil of northern latitudes (Hutchison-Benson et al 1985;France et al 1993). Snow can be easily redistributed to low-lying areas in fields before it melts.…”