Tritiated Water Vapor in the Surface Air at Tokyo

Abstract

   Tritium concentration in water vapor in the air near the surface and in the precipitation at Tokyo was measured during the period from 9 August to 20 November in 1974. From August to the middle of October, tritium mixing ratios in the surface air had relatively higher values except those in air masses which were associated with a typhoon.
   The mixing ratios of tritium in the air decreased abruptly at the middle of October, which indicates the decrease of tritium influx from aloft.
   These data exhibit the salient feature that variations in tritium concentration in TR are linear to the reciprocal of the content of water vapor during each period.
   Tritium concentrations in vapor and rain water collected simultaneously show nearly equal values. One of the reasons for the good correlation of tritium concentration between falling drops and ambient air is considered to be the result of the rapid isotopic exchange.