Tritium transfer parameters for the winter environment

Experimental values for some of the key parameters controlling the transfer of tritiated water vapour (HTO) in the winter environment are reported. The dry deposition velocity (vg) of HTO to snow was found to be 1.6 × 10−3 ± 0.5 × 10−3 ms−1; the washout coefficient (Λ) of HTO by snow was 2.1 × 10−5 ± 1.0 × 10−5 s−1; the deposition velocity to pine needles lay between about 2 × 10−6 ms−1 and 5 × 10−6 ms−1; and the reemission rate of HTO from the snow to the atmosphere was very low. The relatively large uncertainties associated with the results arise from the fact that the parameter values were derived from monitoring data collected following an accidental release of tritium to the atmosphere. A comparison of observed snow core inventories with those predicted using an atmospheric dispersion model lends confidence to the derived values of vg and Λ.