Altitude dependent 137Cs concentrations in different plant species in alpine agricultural areas

The Gastein valley in the Central Part of the Austrian Alps was one of the regions most heavily affected by fallout of the Chernobyl nuclear catastrophe, depositing 137Cs inventory up to 70 kBq/m2 in May 1986. In many studies dealing with the uptake of 137Cs by vegetation used for farming, a significant correlation between 137Cs concentration in the plants and altitude a.s.l. has been observed. In order to quantify the influence of the composition of plant communities on the average 137Cs concentration in vegetation on farmland, plant-specific activity concentrations in plant species have been determined. Alongside a transect from valley sites at 850 m a.s.l. to alpine pastures at 1660 m, the aggregated transfer factors Cag (m2/kg) have been measured for plant communities and plant species. Cag values for mixed vegetation are more or less similar in valley sites, but they increase exponentially with a doubling height of 122 ± 22 m above appr. 1200 m altitude a.s.l. On average all species are affected by this increase in a similar way. Cag values of ubiquitous plant indicate that the composition of plant communities is of minor importance for the contamination of mixed vegetation.