TRITIUM BEHAVIOR ON A CULTIVATED PLOT IN THE 1994 CHRONIC HT RELEASE EXPERIMENT AT CHALK-RIVER

The behavior of HT and HTO in air and surface soil has been studied ex tensively in the chronic HT release experiment carried out at Chalk Ri ver during the summer of 1994. HTO concentrations in air moisture and soil water collected in a cultivated plot showed similar time-variatio ns, increasing rapidly during the first and second days and becoming g radual after the first 3-4 days. The air HTO concentration decreased d uring and following rainfall but recovered within a day. The rainfall reduced the HTO concentrations in ridge soil water but little in furro ws. Time histories of HTO concentrations in air moisture and soil wate r suggest that the system was near steady-state within a continuous HT release period of 12 days, ill spite of the presence of rain during t he period. The air HTO concentrations on clear days showed diurnal cyc les that were higher during daytime than at night. The experimental fi eld had a very complex soil regime with respect to HT deposits. The de posits to soil surface varied depending on soil conditions.