TRITIUM CONCENTRATIONS IN ATMOSPHERIC WATER-VAPOR, HYDROGEN AND HYDROCARBONS IN FUKUOKA

Tritium concentrations of tritiated water vapor (HTO), tritiated hydrogen (HT) and tritiated hydrocarbons (CH3T) in the atmosphere in Fukuoka were measured once a week from 1984 to the present to evaluate the present background levels of atmospheric tritium. Atmospheric HTO concentration varies within a wide range from 5.6 to 61 mBq/m3-air or from 0.8 to 3.2 Bq/L-H2O. HTO concentrations expressed in pCI/m3; they are higher in summer and lower in winter. On the other hand, HT and CH3T concentrations generally show no seasonal variation with almost constant values of 26-70 mBq/m3 and 6.7-34 mBq/m3, respectively. Annual averaged values of the specific activities written in tritium units (TU) are about 16, 9 x 10(5) and 4 x 10(4) for HTO, HT and CH3T, respectively. The results obviously indicate that not only HTO but also HT should be considered in estimating the radiation effect of tritium on human beings.