In Situ Metal Imaging and Zn Ligand-Speciation in a Soil-Dwelling Sentinel: Complementary Electron Microprobe and Synchrotron Microbeam X-ray Analyses

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• 作者：A. J. Morgan ; J. F. W. Mosselmans ; J. M. Charnock ; A. Bennett ; C. Winters ; M. O鈥橰eilly ; P. Fisher ; J. Andre ; M. Turner ; P. Gunning ; P. Kille
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：January 15, 2013
• 年：2013
• 卷：47
• 期：2
• 页码：1073-1081
• 全文大小：501K
• 年卷期：v.47,no.2(January 15, 2013)
• ISSN：1520-5851

文摘

Understanding the relationships between accumulated metal speciation in cells and tissues of ecologically significant taxa such as earthworms will improve risk assessments. Synchrotron-based 渭-focus X-ray spectroscopy was used to detect, localize, and determine ligand-speciation of Zn and Pb in thin sections of two epigeic earthworm species collected from a Pb/Zn-mine soil. The findings indicated that Zn and Pb partition predominantly as typical hard acids (i.e., strong affinities for O-donors) within liverlike chloragocytes. Moreover, Zn speciation was very similar in the chloragog and intestinal epithelia but differed subtly in the kidneylike nephridial tubules; neither Zn nor Pb was detectable in the ventral nerve cord. High resolution X-ray mapping of high pressure-frozen, ultrathin, freeze-substituted sections in a transmission electron microscope (TEM), combined with conventional TEM structural analysis, identified a new cell type packed with highly organized rough endoplasmic reticulum and containing deposits of Cd (codistributed with S); there was no evidence that these cells are major depositories of Zn or Pb. These data may be used in a systems biology approach to assist in the interpretation of metal-evoked perturbations in whole-worm transcriptome and metabolome profiles.