Investigations on deposits of elementary and organically bound iodine on grass. Result report: July 1971--December 1972 (Part II)

Experiments are described in this report which had been executed in the nuclear research facility Julich for the study of iodine deposits on grass and clover. The deposit rates determined in open air tests with natural elementary iodine are discussed on the basis of an empirical equation which covers in addition to meteorological parameters (u2/sub */anti u/), and the mass coverage of the ground with vegetation (dry mass) also biological parameters such as the age of the grass and the growth period by means of a factor. This is a first attempt at taking into account the ''biological quality'' of the grass which obviously strongly affects the deposit. The deposit rates measured are in agreement with those of other authors. In addition to iodine deposits on grass, that of elementary iodine on clover was investigated in one experiment. The deposit rates measured are approximately twice as high as those on grass if they are related to identical mass coverage and meteorological parameters. In an additional test, the biological half life of iodine on grass was studied. A biological half life of (8.0 +- 0.5) d was measured which turns out a little smaller than had been determined in most experiments of other authors with radio iodine. The iodine content of the grass does not reveal any effects of sunshine or rain