In order to quantify the radiation hazard to humans through food, both migration and distribution of 95Zr in Chinese cabbage/soil system were examined by using the radioisotope tracer technique. When 95Zr was administered with simulated irrigation or simulated rainfall, 95Zr was detected in every part of Chinese cabbage, which indicated that 95Zr could be translocated to above-ground parts. Although concentrations of 95Zr in different parts of Chinese cabbage were different in the two treatments used in the present study, the patterns of 95Zr distribution in different parts of the plant were similar. Concentration of 95Zr in each part of Chinese cabbage followed the order of root>leaf>lower part of petiole>upper part of petiole>bud in the case of simulated irrigation. Moreover, the 95Zr could be accumulated in leaves after being taken up by roots. In the simulated irrigation treatment, 95Zr concentrations were 1·7 and 2·9 times higher in the leaf than in the petiole and bud, respectively. In the case of simulated rainfall, a portion of applied 95Zr precipitated on the above-ground parts of Chinese cabbage, which led to a higher concentration here than in the case of simulated irrigation. The results of the present study clearly indicate that there is a distinct possibility that foodstuffs produced in the 95Zr-contaminated area are radioactively contaminated. More than 90% of total 95Zr in soil was retained in the upper layer (0–8 cm), which indicated 95Zr could not easily move downwards because of strong adsorption to soil.
Study on reaction mechanism of coal hydrogenation by means of radioisotope tracer technique.
