DEPOSITION OF D2O FROM AIR TO PLANT AND SOIL DURING AN EXPERIMENT OF D2O VAPOR RELEASE INTO A VINYL HOUSE

Deuterium, a stable isotope of tritium, was released into a vinyl hous e in autumn 1995 and summer 1996 to study the transfer of tritium from air to plant and soil. Temporal variation of D2O concentrations in pl ant and soil water, and plant physiological parameters such as transpi ration rate and leaf temperature, were measured during these experimen ts. D2O concentrations of plants were fitted to a first order kinetic model: C-p = C-max (1 - e(-kt)), where C-p is the D2O concentrations i n plants at time t, C-max is the steady-state concentration in plants and k is the rate constant. The rate constant was also calculated usin g measured plant physiological parameters for comparison. The D2O upta ke by paddy rice was most rapid and the value of k was 3.63 +/- 0.31 h (-1) followed by radish, cherry tomato, Komatsuna and orange. The day/ night concentration ratio for cherry tomato and orange was higher than that for radish and Komatsuna. (C) 1998 Elsevier Science S.A. All rig hts reserved.