Zhu Y G, Smolders E
Department of Soil and Water, and CRC for Molecular Plant Breeding, The University of Adelaide, Glen Osmond, SA 5064, Australia.
J Exp Bot. 2000 Oct;51(351):1635-45. doi: 10.1093/jexbot/51.351.1635.
Soil contamination with radiocaesium (Cs) has a long-term radiological impact because it is readily transferred through food chains to human beings. Plant uptake is the major pathway for the migration of radiocaesium from soil to human diet. The plant-related factors that control the uptake of radiocaesium are reviewed. Of these, K supply exerts the greatest influence on Cs uptake from solution. It appears that the uptake of radiocaesium is operated mainly by two transport pathways on plant root cell membranes, namely the K(+) transporter and the K(+) channel pathway. Cationic interactions between K and Cs on isolated K-channels or K transporters are in agreement with studies using intact plants. The K(+) transporter functioning at low external potassium concentration (often <0.3 mM) shows little discrimination against Cs(+), while the K(+) channel is dominant at high external potassium concentration with high discrimination against Cs(+). Caesium has a high mobility within plants. Although radiocaesium is most likely taken up by the K transport systems within the plant, the Cs:K ratio is not uniform within the plant. Difference in internal Cs concentration (when expressed on a dry mass basis) may vary by a factor of 20 between different plant species grown under similar conditions. Phytoremediation may be a possible option to decontaminate radiocaesium-contaminated soils, but its major limitation is that it takes an excessively long time (tens of years) and produces large volumes of waste.
放射性铯（Cs）对土壤的污染具有长期的放射性影响，因为它很容易通过食物链转移到人类身上。植物吸收是放射性铯从土壤迁移到人类饮食中的主要途径。本文综述了控制放射性铯吸收的与植物相关的因素。其中，钾供应对溶液中铯的吸收影响最大。放射性铯的吸收似乎主要通过植物根细胞膜上的两种运输途径进行，即钾离子转运体和钾离子通道途径。在分离的钾通道或钾转运体上钾和铯之间的阳离子相互作用与使用完整植物的研究结果一致。在外部钾浓度较低（通常<0.3 mM）时起作用的钾离子转运体对铯离子的区分能力较弱，而钾离子通道在外部钾浓度较高时占主导地位，对铯离子有较高的区分能力。铯在植物体内具有较高的迁移性。虽然放射性铯很可能是通过植物体内的钾运输系统吸收的，但植物体内的铯钾比并不均匀。在相似条件下生长的不同植物物种之间，内部铯浓度（以干重计）的差异可能相差20倍。植物修复可能是对受放射性铯污染土壤进行去污的一种可行选择，但其主要局限性在于耗时过长（数十年）且会产生大量废物。
