137Cs and 90Sr transfer to milk in Austrian alpine agriculture

The alpine regions of Austria were among the most contaminated territories outside of the former USSR after the Chernobyl accident. In the investigated province of Salzburg the median 137Cs surface deposition was 31.4 kBq m−2 with maximum values exceeding 90 kBq m−2 (May 1986). To quantify the transfer of 137Cs and 90Sr from vegetation to milk in these seminatural conditions nine seasonally grazed alps were identified and vegetation and milk sampled during summer 2002 and summer 2003. Mean ± SD milk transfer coefficients (fm) for 137Cs and 90Sr were 0.0071 ± 0.0009 d l−1, and 0.0011 ± 0.0004 d l−1, respectively; which for 137Cs is markedly higher than those fm values found in intensive agricultural systems. Transfer kinetics for 137Cs into cow milk were approximated using a 2-compartment model with a short and a long-term component. Fitting the model to empirical data results in reliable estimates of the time constant of the short-term component, biological half-life 1.06 ± 0.28 d, whereas the estimates of the long-term component are subject to high uncertainties.