Tritium in the German Bight 1980 to 1995. Trends of activity and balance

Full text: Since 1980 seawater samples have been taken yearly in the German Bight on 9 fixed stations for tritium analysis. The initial mean value of 1.9 Bq/l measured in 1980 changed to a concentration of 1.1 Bq/l in 1992 and is now increasing to 2.8 Bq/l in 1995. The accumulated effect to the German Bight derived from the tritium sources discharging into the adjacent seas is calculated by transfer factors. The calculations take into account the yearly liquid discharges from the nuclear reprocessing plants and power stations into the British and French coastal waters as well as the tritium concentration in the Atlantic and North Sea water, the rain water input and the freshwater tributaries to the southern North Sea. The activity values used are taken both from literature and own measurements. The results show that the nuclear weapons fallout was the predominant source in 1980. Nowadays the nuclear power industry is the main source of tritium concentration in the German Bight. The poster demonstrates the temporal development of the activity concentration measured in relation to the calculated contributions. The geographic locations of the sample stations and the sites of the sources are displayed. Moreover, the individual sources and their tritium discharges (in 1993, as an example) as well as the transfer factors used are listed