Using X-ray microscopy and Hg L3 XANES to study Hg binding in the rhizosphere of Spartina cordgrass.
Using X-ray microscopy and Hg L3 XANES to study Hg binding in the rhizosphere of Spartina cordgrass.
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DOI：
10.1021/es901076q
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发表时间：
2009-10-01
影响因子：
11.4
通讯作者：
Andrews, Joy C.
中科院分区：
文献类型：
--
作者：
Patty, Cynthia;Barnett, Brandy;Mooney, Bridget;Kahn, Amanda;Levy, Silvio;Liu, Yijin;Pianetta, Piero;Andrews, Joy C.
旧金山弗朗西斯科湾历史上一直受到来自矿山尾矿以及当代工业来源的汞污染。原生米草和非原生米草。互花米草-杂交灯心草是SF湾河口环境中的优势植物群。了解这些植物对汞的吸收和转化，将有助于了解它们在河口环境汞地球化学循环中的作用。甲基化汞可通过生物放大作用进入食物网，导致游猎鱼体内的甲基化汞含量比周围沃茨高出100万倍，从而导致人们不得不限制鱼类摄入量。了解汞在植物根际的吸收和甲基化可以深入了解汞污染的管理方法。在斯坦福大学同步辐射光源（SSRL）的光束线6-2上的透射X射线显微镜被用于获得吸收对比度图像和3D断层扫描的米草根，所述根被暴露于1 ppm Hg（作为HgCl 2）水培一周。S.微米级根的吸收衬度图像。foliosa揭示了黑色颗粒，和黑暗的通道内的根，由于汞的吸收。3D断层扫描显示颗粒位于牙根表面，断层扫描重建的切片显示颗粒是中空的，与表面有一薄层Hg的微生物一致。汞L3 XANES的地面上的植物根和汞L3微XANES从微探针分析微米大小的根（60-120微米的大小）揭示了三种主要类型的物种在两个米草属物种：汞-硫连接的形式类似于汞（II）半胱氨酸，汞-硫键合的朱砂和metacinnabar，和甲基汞-羧基键合的形式类似于醋酸甲基汞。这些结果被解释的背景下，获得一个“快照”的汞甲基化的进展。
San Francisco Bay has been contaminated historically by mercury from mine tailings as well as contemporary industrial sources. Native Spartina foliosa and non-native S. alterniflora-hybrid cordgrasses are dominant florae within the SF Bay estuary environment. Understanding mercury uptake and transformations in these plants will help to characterize the significance of their roles in mercury biogeochemical cycling in the estuarine environment. Methylated mercury can be biomagnified up the food web, resulting in levels in sport fish up to one million times greater than in surrounding waters and resulting in advisories to limit fish intake. Understanding the uptake and methylation of mercury in the plant rhizosphere can yield insight into ways to manage mercury contamination. The transmission x-ray microscope on beamline 6-2 at the Stanford Synchrotron Radiation Lightsource (SSRL) was used to obtain absorption contrast images and 3D tomography of Spartina foliosa roots that were exposed to 1 ppm Hg (as HgCl2) hydroponically for one week. Absorption contrast images of micron-sized roots from S. foliosa revealed dark particles, and dark channels within the root, due to Hg absorption. 3D tomography showed that the particles are on the root surface, and slices from the tomographic reconstruction revealed that the particles are hollow, consistent with microorganisms with a thin layer of Hg on the surface. Hg L3 XANES of ground-up plant roots and Hg L3 micro-XANES from microprobe analysis of micron-sized roots (60–120 microns in size) revealed three main types of speciation in both Spartina species: Hg-S ligation in a form similar to Hg(II) cysteine, Hg-S bonding as in cinnabar and metacinnabar, and methylmercury-carboxyl bonding in a form similar to methylmercury acetate. These results are interpreted within the context of obtaining a “snapshot” of mercury methylation in progress.
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影响因子：
2.9
作者：
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通讯作者：
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