Comparative behaviour of recently deposited radiostrontium and atmospheric common strontium in soils (Vosges mountains, France)

The vertical distribution of atmospheric 87Sr/86Sr isotope ratios in soil is compared to the distribution of recent atmospheric 90Sr deposition. 87Sr/86Sr isotope ratios of soil leachates are correlated with 90Sr activities. Samples from the uppermost part of a soil profile have low 87Sr/86Sr ratios and high 90Sr activities. Samples from the deeper part of the soil profile, however, have high 87Sr/86Sr but low 90Sr activities. This points to mixing between an atmospheric and a geogenic component. Mixing calculations indicate that 50–80% of the Sr in the topsoil of a small catchment in the Vosges mountains is of atmospheric origin. Similarly 87Sr/86Sr of roots point to the presence of an atmospheric and geogenic component. 87Sr/86Sr ratios of soil leachates and corresponding roots are very similar indicating, that the roots integrate at each level of the soil profile the leachable Sr of the corresponding soil.