Trace amounts of tritiated hydrogen (HT) were released continuously to
the atmosphere at Chalk River Laboratories over the 12-day period 199
4 July 27 to August 8. Scientists from eight institutions in four coun
tries took extensive air, soil and vegetation samples to study the dyn
amics of tritiated water (HTO) and organically-bound tritium (OBT) for
mation, and the environmental concentrations of these compounds at ste
ady-state. The short-term HT air concentrations varied strongly in tim
e and space over the test area, but the variation decreased rapidly as
the averaging time increased. HTO concentrations in soil, vegetation
and air built up gradually over time but they fluctuated substantially
with ambient meteorological conditions, particularly rainfall. OBT co
ncentrations in plants increased throughout the period. HTO concentrat
ions were at or near steady-state at the end of the release, but OBT l
evels were continuing to rise.