空气凤梨对天然放射性气体－氡的监测与修复研究

As the unique natural radioactive gas, Radon (Rn) is the primary source of natural nuclear radiation. It is an invisible, odorless and colorless gas that seeps up through the ground and diffuses into the air. So it's essential to find sensitive ways monitoring and purifying Rn and it's daughters. It is well known that some plant species can accumulate toxic compounds without any deleterious effects, and may therefore be used as quantitative monitoring systems. Epiphytic Tillandsia species, known as air plants, have been used to monitor atmospheric heavy metal and nuclide pollution, because they have no true root systems and obtain pollutants from the ambient air instead of soil. The stem and leaves of Tillandsia are completely covered by powdery epicuticular waxy foliar trichomes, while Rn is easily disolved in fats and lipids. Therefore, we want to monitor and purify Rn with epiphytic Tillandsia species, to discuss whether Tillandsia with waxy floiar trichomes can effectivly adsorb air pollutant Rn. At the same time, we will discuss whether Tillandsia species are sensible monitoring plants through the study of visible morphological or physiological changes of Tillandsia after exposure to Rn contamination.

做为自然界唯一的天然放射性气体，氡是人类受天然辐射的主要来源。但是，氡气无色无味，日常生活中难以被人们感知。如何灵敏、方便地监测到氡气的存在并采取有效的措施减少氡及其子体的危害成为人们辐射防护的关键。空气凤梨是一类能够生长于空气中的特殊观赏植物，它们依靠叶片直接吸收空气中的污染物，已被证明能够快速灵敏地监测与修复大气重金属和核素污染物。空气凤梨叶表面覆盖着富含蜡质的鳞片，而氡极易溶于脂肪。因此，本项目拟利用几种空气凤梨对放射性气体氡污染进行监测和净化研究，探讨叶表面富含蜡质鳞片的空气凤梨是否能有效吸收极易溶于脂的氡，从而成为有效的去除氡污染的植物；同时探讨空气凤梨在经过氡污染后是否出现较易辨别的形态或生理生化变化，从而成为灵敏的指示氡污染的植物，为氡的净化和环境污染治理提供有效地植物修复途径。

氡是自然界含量最高的天然放射性气体，是人类辐射的主要来源。但氡又是一种惰性气体，植物一直以来被认为不可能有效吸收氡。本项目选择特殊植物类群-空气凤梨为研究对象，将其置于标准氡室中进行不同浓度的氡气薰蒸，检测了氡及氡子体浓度变化和植物的各种形态、生理、分子指标。首次证明氡可被某些特殊植物所吸收，因为加入空气凤梨后，氡室中氡浓度明显下降的更快，而且植物体内可检测到氡子体210Pb。在这一过程中，空气凤梨叶表鳞片起着重要作用，因为氡易溶于脂质成分，GC-MS实验表明空气凤梨蜡质成分主要存在于叶表鳞片上；而人工去除鳞片后，其吸收氡的能力显著下降。随着氡浓度增加, 表征DNA 损伤程度的4 个参数Tail length, Tail DNA , TM , OTM 以及MDA含量都随之增加，说明空气凤梨不可避免的遭受了来自于氡的辐射损伤。但SOD活性也显著升高，说明植物体内活性氧清除体系开始发挥作用，能够在一定程度上提高植物的抗性。因此，方便移动的附生植物空气凤梨具有广泛应用到氡防控系统的潜能。