Continuous wet-only and dry-only deposition measurements of 137Cs and 7Be: an indicator of their origin

Series of monthly values of 137Cs and 7Be wet and dry deposition were measured with a wet-only and a dry-only collector each having an area of 2.25 m2. The results are presented for the period from November 1991 to May 1995. The behaviour of resuspended, Chernobyl-derived radiocesium is shown to be significantly different from that of cosmogenic 7Be and from that of global fallout 137Cs from nuclear weapons testing. The dry-to-total ratio of 0.65, the dry deposition velocity of 1.5 cm s−1, the close correlation to the total amount of solids collected and the absence of a correlation between activity deposition and amount of rainfall point to a strong similarity in the deposition behaviour of present radiocesium and that of stable elements of terrestrial origin such as Fe, Al, Ca, Mg etc.