氚化水蒸汽晚上和白天短期释放情况下花生中氚含量的研究

为研究氚化水(HTO)蒸汽晚上和白天短期释放情况下花生对HTO的吸收和有机氚(OBT)形成的差异,利用盆栽试验在花生开花下针期和结荚期分白天和晚上模拟HTO的短期释放,并在试验结束和收获时分别测量叶子和果实中组织自由水氚(TFWT)和OBT的含量。研究结果表明,花生叶子晚上对HTO的吸收小于白天。开花下针期晚上暴露试验结束时,叶子中TFWT和OBT的相对浓度分别是白天相应值的1/6和1/3;收获时叶子中的TFWT和OBT均小于暴露试验结束时的值。结荚期晚上暴露试验结束时,花生叶子和果实中TFWT和OBT的相对浓度分别是白天相应值的1/3、2/3和2/3、1.13倍,收获时果实中的TFWT大于暴露试验结束时的值,叶子中OBT的相对浓度为暴露试验结束时的1.7倍,果实中OBT相对浓度却减少为原来的1/4;而白天试验收获时叶子中OBT的相对浓度小于试验结束时的值,但果实中OBT的相对浓度大于暴露试验结束时的值。表明HTO在不同生育期白天和晚上释放情况下,花生叶子和果实中TFWT和OBT的变化趋势不同,所以在气态氚短期释放情况下预测植物中的OBT浓度时,应根据不同的释放时间选择相应的参数。

Study on Tritium Concentration in Peanut after Short-term Exposure to Atmospheric HTO at Nighttime and Daytime

In order to study the differences of HTO uptake and OBT formation in peanut following a short atmospheric HTO release in nighttime and daytime condition, the potted peanut plants were exposed to evaporated HTO for 1 h in an exposure box at the flowering and podding stages under nighttime and daytime, respectively. The concentrations of tissue free water tritium (TFWT) and organically bound tritium (OBT) in leaves and peanut kernels were measured at the end of the exposure and at the harvest, respectively. The results show that HTO uptake in peanut leaves during the nighttime is several times lower than that during the daytime. At the flowering stage, the relative TFWT and OBT concentrations in leaves under night conditions at the end of the exposure are about one sixth and one third from the concentration for day conditions. And at the harvest, the TFWT and OBT concentrations of leaves are lower than that at the end of exposure. At the podding stage, the relative TFWT and OBT concentrations in leaves and peanut kernels under night conditions are one third, two third and two third, 1.13 times from the concentration under day conditions at the end of exposure. At the harvest, the TFWT concentration in peanut kernels is higher than that at end of the exposure, and the relative OBT concentration in leaves increases by factor of 1.7, but the OBT concentration in peanut kernels is only one fourth of that at the end of exposure under night condition. At the harvest, the OBT concentration in leaves is lower than that at the end of exposure, however the OBT concentration in kernels increases under day condition. Following a short atmospheric HTO release in nighttime and daytime conditions at the different growth and development stages, the variation tendency of TFWT and OBT in leaves and kernels are different. Therefore, the parameters of tritium concentration prediction model in plant should base the growth stages for accidental release of atmospheric HTO, which could make the ingestion doses for tritium be estimated accurately and objectively.