Wang Weiqing, Gert Dudel E
Institute of Plant and Wood Chemistry, Dresden University of Technology, Pienner Strasse 19, D-01737, Tharandt, Germany.
Environ Sci Pollut Res Int. 2017 May;24(13):12185-12194. doi: 10.1007/s11356-017-8889-5. Epub 2017 Mar 28.
Studies have revealed that the rhizofiltration is a feasible plant-based technology for aquatic metal/metalloid removal. However, the performance of aquatic U retention via rhizofiltration has not been fully revealed yet. In this study, a field investigation was conducted in a Phragmites australis Trin ex Steud. dominated wetland to estimate the efficiency of Fe plaque (IP)-assisted U rhizofiltration, with redox-state gradient (-179 to 220 mV) and low aquatic U level (66.7 to 92.0 μg l). The U concentrations were determined in soil, root, and aboveground biomass of P. australis. The IP on root surface was extracted via DCB extraction procedure. The bio-concentration factor (BCF) was applied to evaluate the aquatic U transfer capacity from root to above ground biomass of P. australis. The result suggested that root of P. australis was highly effective for aquatic U uptake via rhizofiltration (BCF 1025 to 1556). It also benefited the real U accumulation in aboveground biomass of P. australis (up to 0.4 mg m) and related plant-water-soil U recycling. The IP and associated microbial community in rhizosphere was effective mediator for aquatic U retention on root surface (BCF 1162 to 847). The IP-assisted aquatic U rhizofiltration was significantly promoted in relatively reductive environment. It was benefited by the enhanced root uptake of Fe due to lower oxidizers (e.g., DO and NO) availability. On the other hand, the competitive adsorption effect from co-existing IP-affinitive elements (e.g., As) also possibly impaired the real capacity of IP-assisted aquatic U rhizofiltration via P. australis.
研究表明，根际过滤是一种可行的基于植物的去除水体中金属/类金属的技术。然而，通过根际过滤去除水体中铀的性能尚未完全揭示。在本研究中，在以芦苇（Phragmites australis Trin ex Steud.）为主的湿地进行了实地调查，以评估铁锰氧化物胶膜（IP）辅助的铀根际过滤效率，该湿地具有氧化还原态梯度（-179至220 mV）且水体铀含量较低（66.7至92.0 μg l）。测定了芦苇的土壤、根系和地上生物量中的铀浓度。通过DCB提取法提取根表面的铁锰氧化物胶膜。应用生物富集系数（BCF）评估水体中铀从芦苇根系向地上生物量的转移能力。结果表明，芦苇根系通过根际过滤对水体铀的吸收非常有效（BCF为1025至1556）。这也有利于芦苇地上生物量中实际铀的积累（高达0.4 mg m）以及相关的植物-水-土壤铀循环。根际的铁锰氧化物胶膜及相关微生物群落是水体铀在根表面滞留的有效介质（BCF为1162至847）。在相对还原的环境中，铁锰氧化物胶膜辅助的水体铀根际过滤得到显著促进。这得益于较低的氧化剂（如溶解氧和硝酸盐）可用性增强了根系对铁的吸收。另一方面，共存的与铁锰氧化物胶膜亲和的元素（如砷）的竞争吸附作用也可能削弱了通过芦苇进行的铁锰氧化物胶膜辅助的水体铀根际过滤的实际能力。
