Department of Earth and Environmental Studies, Montclair State University, Montclair, New Jersey 07043, USA.
School of Marine and Atmospheric Science, State University of New York, Stony Brook, NY 11794, USA.
Sci Rep. 2017 Jan 18;7:40420. doi: 10.1038/srep40420.
This paper reports a nanometer-scale investigation of trace element (As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn) distributions in the root system Spartina alterniflora during dormancy. The sample was collected on a salt marsh island in Jamaica Bay, New York, in April 2015 and the root was cross-sectioned with 10 μm resolution. Synchrotron X-ray nanofluorescence was applied to map the trace element distributions in selected areas of the root epidermis and endodermis. The sampling resolution was 60 nm to increase the measurement accuracy and reduce the uncertainty. The results indicate that the elemental concentrations in the epidermis, outer endodermis and inner endodermis are significantly (p < 0.01) different. The root endodermis has relatively higher concentrations of these elements than the root epidermis. Furthermore, this high resolution measurement indicates that the elemental concentrations in the outer endodermis are significantly (p < 0.01) higher than those in the inner endodermis. These results suggest that the Casparian strip may play a role in governing the aplastic transport of these elements. Pearson correlation analysis on the average concentrations of each element in the selected areas shows that most of the elements are significantly (p < 0.05) correlated, which suggests that these elements may share the same transport pathways.
本文报告了对休眠期盐沼植物互花米草根系中微量元素（As、Ca、Cr、Cu、Fe、Mn、Ni、S 和 Zn）分布的纳米尺度研究。样品于 2015 年 4 月在纽约牙买加湾的一个盐沼岛上采集，并用 10μm 分辨率对根系进行了横切。同步辐射 X 射线荧光纳米探针用于绘制根系表皮和内皮层选定区域的微量元素分布。采样分辨率为 60nm，以提高测量精度和降低不确定性。结果表明，表皮、外皮层和内皮层中的元素浓度差异显著（p<0.01）。根内皮层的这些元素浓度明显高于根表皮。此外，这种高分辨率测量表明，外皮层的元素浓度明显高于内皮层（p<0.01）。这些结果表明，凯氏带可能在控制这些元素的非质体运输中起作用。对选定区域中每个元素平均浓度的 Pearson 相关性分析表明，大多数元素显著相关（p<0.05），这表明这些元素可能共享相同的运输途径。
