Concentrations of (137)Cs in summer pasture plants that reindeer feed on in the reindeer management area of Finland

Abstract

Samples of summer pasture plants that reindeer feed on were collected in order to study (137)Cs concentrations in different plant species and in species nested in certain site types, and to study the regional distribution of (137)Cs in the Finnish reindeer management area. Plant species were categorized by the site types of mineral soil forest (xeric heath forest and mesic heath forest) and peatland. A third category called 'other plant species' included plants with various site types, poorly determined species and species with poor statistics. The (137)Cs concentrations in different site types differed significantly. The mean (137)Cs concentrations of the whole reindeer management area in the xeric heath forest plant species was 44 ± 27 Bq/kg dw, in the mesic heath forest plant species 75 ± 59 Bq/kg dw and in the peatland plant species 219 ± 150 Bq/kg dw. The peatland species uptake (137)Cs more efficiently than plant species of mineral soil forests. A particularly efficient collector of (137)Cs was Trichophorum sp. It is suggested that Trichophorum sp. could be used as an indicator species for reindeer summer fodder plants. The highest concentrations of (137)Cs were found in Southern Lapland and the lowest in Northern Lapland. Today, the concentrations of (137)Cs in summer pasture plants that reindeer feed on in Finland are at such a level that there is no need to avoid any plant species. In the case of future nuclear fallout, reindeer grazing in peatlands would increase concentrations of (137)Cs in reindeer meat.