Radiocesium storage in soil microbial biomass of undisturbed alpine meadow soils and its relation to 137Cs soil-plant transfer

This study focuses on radiocesium storage in soil microbial biomass of undisturbed alpine meadow sites and its relation to the soil-to-plant transfer. Soil and plant samples were taken in August 1999 from an altitude transect (800-1600 m.a.s.l.) at Gastein valley, Austria. Soil samples were subdivided into 3-cm layers for analyses of total, K2SO4-extractable and microbially stored 137Cs. Microbial biomass was measured by the fumigation extraction method, and fungal biomass was quantified using ergosterol as biomarker molecule. In general, the quantity of 137Cs stored in the living soil microbial biomass was relatively small. At the high-altitude meadows, showing high amounts of fungal biomass, microbially stored 137Cs amounted to 0.64 ± 0.14 kBq m−2 which corresponds to about 1.2-2.7% of the total 137Cs soil inventory. At lower altitudes, microbial 137Cs content was distinctly smaller and in most cases not measurable at all using the fumigation extraction method. However, a positive correlation between the observed soil-to-plant aggregated transfer factor, microbially stored 137Cs and fungal biomass was found, which indicates a possible role of fungal biomass in the storage and turnover of 137Cs in soils and in the 137Cs uptake by plants.