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Emerging investigator series: entrapment of uranium–phosphorus nanocrystals inside root cells of Tamarix plants from a mine waste site
Environmental Science: Processes & Impacts ( IF 5.5 ) Pub Date : 2020-12-8 , DOI: 10.1039/d0em00306a Lucia Rodriguez-Freire 1 , Cherie L DeVore 2 , Eliane El Hayek 3 , Debora Berti 4 , Abdul-Mehdi S Ali 5 , Juan S Lezama Pacheco 6 , Johanna M Blake 7 , Michael N Spilde 5 , Adrian J Brearley 5 , Kateryna Artyushkova 8 , José M Cerrato 2
Environmental Science: Processes & Impacts ( IF 5.5 ) Pub Date : 2020-12-8 , DOI: 10.1039/d0em00306a Lucia Rodriguez-Freire 1 , Cherie L DeVore 2 , Eliane El Hayek 3 , Debora Berti 4 , Abdul-Mehdi S Ali 5 , Juan S Lezama Pacheco 6 , Johanna M Blake 7 , Michael N Spilde 5 , Adrian J Brearley 5 , Kateryna Artyushkova 8 , José M Cerrato 2
Affiliation
We investigated the mechanisms of uranium (U) uptake by Tamarix (salt cedars) growing along the Rio Paguate, which flows throughout the Jackpile mine near Pueblo de Laguna, New Mexico. Tamarix were selected for this study due to the detection of U in the roots and shoots of field collected plants (0.6–58.9 mg kg−1), presenting an average bioconcentration factor greater than 1. Synchrotron-based micro X-ray fluorescence analyses of plant roots collected from the field indicate that the accumulation of U occurs in the cortex of the root. The mechanisms for U accumulation in the roots of Tamarix were further investigated in controlled-laboratory experiments where living roots of field plants were macerated for 24 h or 2 weeks in a solution containing 100 μM U. The U concentration in the solution decreased 36–59% after 24 h, and 49–65% in two weeks. Microscopic and spectroscopic analyses detected U precipitation in the root cell walls near the xylems of the roots, confirming the initial results from the field samples. High-resolution TEM was used to study the U fate inside the root cells, and needle-like U–P nanocrystals, with diameter <7 nm, were found entrapped inside vacuoles in cells. EXAFS shell-by-shell fitting suggest that U is associated with carbon functional groups. The preferable binding of U to the root cell walls may explain the U retention in the roots of Tamarix, followed by U–P crystal precipitation, and pinocytotic active transport and cellular entrapment. This process resulted in a limited translocation of U to the shoots in Tamarix plants. This study contributes to better understanding of the physicochemical mechanisms affecting the U uptake and accumulation by plants growing near contaminated sites.
中文翻译:
新兴研究者系列:铀-磷纳米晶体在矿山废料场的柽柳植物根细胞内的截留
我们调查了沿着 Rio Paguate 生长的Tamarix (盐雪松)吸收铀 (U) 的机制,该河流流经新墨西哥州 Pueblo de Laguna 附近的 Jackpile 矿。由于在田间采集植物的根和芽中检测到 U (0.6–58.9 mg kg -1 ),因此选择柽柳用于本研究,呈现出大于 1 的平均生物浓缩因子。基于同步加速器的微 X 射线荧光分析从田间采集的植物根系表明 U 的积累发生在根部的皮层中。柽柳根系U积累机制在受控实验室实验中进一步研究,其中田间植物的活根在含有 100 μM U 的溶液中浸渍 24 小时或 2 周。溶液中的 U 浓度在 24 小时后下降 36-59%,49-65%在两周内。显微镜和光谱分析在根木质部附近的根细胞壁中检测到 U 沉淀,证实了田间样品的初步结果。高分辨率 TEM 用于研究根细胞内的 U 命运,发现直径 <7 nm 的针状 U-P 纳米晶体被包裹在细胞的液泡内。EXAFS 逐壳拟合表明 U 与碳官能团有关。U 与根细胞壁的优选结合可以解释柽柳根中的 U 保留,然后是 U-P 晶体沉淀,以及胞饮主动转运和细胞诱捕。这一过程导致 U 有限地转移到柽柳植物的枝条上。这项研究有助于更好地了解影响在污染场地附近生长的植物吸收和积累 U 的物理化学机制。
更新日期:2020-12-16
中文翻译:
新兴研究者系列:铀-磷纳米晶体在矿山废料场的柽柳植物根细胞内的截留
我们调查了沿着 Rio Paguate 生长的Tamarix (盐雪松)吸收铀 (U) 的机制,该河流流经新墨西哥州 Pueblo de Laguna 附近的 Jackpile 矿。由于在田间采集植物的根和芽中检测到 U (0.6–58.9 mg kg -1 ),因此选择柽柳用于本研究,呈现出大于 1 的平均生物浓缩因子。基于同步加速器的微 X 射线荧光分析从田间采集的植物根系表明 U 的积累发生在根部的皮层中。柽柳根系U积累机制在受控实验室实验中进一步研究,其中田间植物的活根在含有 100 μM U 的溶液中浸渍 24 小时或 2 周。溶液中的 U 浓度在 24 小时后下降 36-59%,49-65%在两周内。显微镜和光谱分析在根木质部附近的根细胞壁中检测到 U 沉淀,证实了田间样品的初步结果。高分辨率 TEM 用于研究根细胞内的 U 命运,发现直径 <7 nm 的针状 U-P 纳米晶体被包裹在细胞的液泡内。EXAFS 逐壳拟合表明 U 与碳官能团有关。U 与根细胞壁的优选结合可以解释柽柳根中的 U 保留,然后是 U-P 晶体沉淀,以及胞饮主动转运和细胞诱捕。这一过程导致 U 有限地转移到柽柳植物的枝条上。这项研究有助于更好地了解影响在污染场地附近生长的植物吸收和积累 U 的物理化学机制。