Iodine-129 in rainfall over Germany

Concentrations of 129I in rain, total deposition of 129I and 129I/127I isotope ratios at five sampling sites distributed over West-Germany were determined in 1994 and 1995 by neutron activation analysis. The different species of 129I in rain water — 129I attached to particulate matter, inorganic and organic forms of 129I — were also determined. The average concentration of 129I in rain ranged between (0.8±0.2)×10-12 g l-1 and (2.4±0.7)×10-12 g l-1 in the year 1994 and (1.3±0.4)×10-12 g l-1 and (3.2±0.9)×10-12 g l-1 in the year 1995. The total annual deposition of 129I varied from 7.8×10-10 g m-2 to 16.3×10-10 g m-2 in the year 1995. The concentrations of the inorganic fractions are the highest at most sampling sites. Values of inorganic 129I were found to range from 43.8% to 79.1%. The average 129I/127I isotope ratios vary between (9.7±3.9)×10-7 and (6.0±2.5)×10-7 during the year 1995. The data point to the North Sea as a huge 129I source, where most of the 129I emissions of the nuclear fuel reprocessing facilities at la Hague (France) and Sellafield (UK) end up.