Tritium inventory of the Black Sea

Tritium and helium-3 measurements from the southern half of the Black Sea a re described. A tritium maximum centered at approximately 1200 m and accomp anied by a radiogenic helium-3 maximum suggests deep injection of near surf ace water in the eastern part of the basin. The results are combined with t hree other tritium data sets to discern the temporal variation in the past three decades. The observed temporal variation is slower than would be expe cted from radioactive decay alone in the upper few hundred meters where the major proportion of tritium resides. This trend suggests that there must h ave been a tritium source(s) other than that produced by the atmospheric nu clear tests. It is estimated that approximately 0.1 kg of tritium of non-at mospheric origin had entered the Black Sea since 1969. (C) 1999 Esevier Sci ence Ltd. All rights reserved.