Fibre crops as alternative lan use for radioactively contaminated arable land

The transfer of radiocaesium, one of the most important and widespread contaminants following a nuclear accident to fibre crops hemp (Cannabis sativa L.) and flax (Linum usitatissimum L.) as well as the distribution of the activity during crop conversion were studied for sandy soil under greenhouse and lysimeters conditions. Soil parameters did not unequivoqually explain the transfer factors (TF) observed. TFs to flax stems ranged from 1.34 to 2.80 10-3m² kg-1. TFs to seeds are about a factor of 4 lower. During the retting process for separating the fibres from the straw, more than 95 % of the activity was removed with the retting water. For hemp, the TF to the stem was about 0.6 10-3m² kg-1. For hemp, straw and fibres were mechanically separated and TF to straw was about 0.5 10-3 m² kg-1 and to fibres 1.0 10-3m² kg-1. Generally, the TFs to the useable plant parts both for hemp and flax, are low enough to allow for the production of clean end products (fibre, seed oil, biofuel) even on heavily contaminated land. Given the high decontamination level during retting, contamination levels in flax fibres will only under conditions from extreme contamination scenarios (>12300 kBq m-2) exceed the exemption limits for fibre use. Since hemp fibres are mechanically separated, use of hemp fibres is more restricted (contamination <740 kBq m-2). Use of stems as biofuel is restricted to areas with contamination levels of