Chemical form of volatilized iodine obtained from orchard grass (<i>Dactylis glomerata</i> L.)

Japan's first commercial nuclear fuel reprocessing plant is expected to release radioiodine into the atmosphere, and orchard grass plants grown in the vicinity of this plant may absorb this radioiodine. In this study, we investigated the mechanism underlying the absorption and volatilization of iodine in the leaves of orchard grass. Our findings suggest that iodine can be transferred from the leaves of this grass to the atmosphere via two routes: direct volatilization and absorption followed by volatilization. Previous studies on rice and oats also show that iodine can be absorbed by the roots and volatilized from the plant's body. Although orchard grass absorbs iodine via the leaves, the chemical form of volatilized iodine may differ from that absorbed via the roots. We applied a NaI solution to the leaves of orchard grass and analyzed the volatilized iodine. The experimental results showed that the iodine was volatilized as methyl iodide.