Field measurements of key parameters associated with nocturnal OBT formation in vegetables grown under Canadian conditions

The objective of this study was to provide the parameter values required to model OBT formation in the edible parts of plants following a hypothetical accidental tritium release to the atmosphere at night. The parameters considered were leaf area index, stomatal resistance, photosynthesis rate, the photosynthetic production rate of starch, the nocturnal hydrolysis rate of starch, the fraction of starch produced daily by photosynthesis that appears in the fruits, and the mass of the fruit. Values of these parameters were obtained in the summer of 2002 for lettuce, radishes and tomatoes grown under typical Canadian environmental conditions. Based on the maximum observed photosynthetic rate and growth rate, the fraction of starch translocated to the fruit was calculated to be 17% for tomato fruit and 14% for radish root.

► Plant physiological parameters affecting nocturnal OBT formation have been investigated.
► The fraction of starch produced daily by photosynthesis in the leaves that appears in the fruit was calculated.
► Realistic estimates of OBT concentrations following a nighttime accidental HTO release to the atmosphere.