Laboratoire de Minéralogie et Cosmochimie du Muséum, UMR 7202 CNRS/MNHN, Muséum National d'Histoire Naturelle, Paris, France.
Environ Sci Technol. 2012 Apr 3;46(7):3943-9. doi: 10.1021/es203745k. Epub 2012 Mar 14.
Direct observations of processes occurring at the mineral-organic interface are increasingly seen as relevant for the cycling of both natural soil organic matter and organic contaminants in soils and sediments. Advanced analytical tools with the capability to visualize and characterize organic matter at the submicrometer scale, such as Nano Secondary Ion Mass Spectrometry (NanoSIMS) and Scanning Transmission X-ray Microscopy (STXM) coupled to Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS), may be combined to locate and characterize mineral-associated organic matter. Taking advantage of samples collected from a decadal (15)N litter labeling experiment in a temperate forest, we demonstrate the potential of NanoSIMS to image intact soil particles and to detect spots of isotopic enrichment even at low levels of (15)N application. We show how microsites of isotopic enrichment detected by NanoSIMS can be speciated by STXM-NEXAFS performed on the same particle. Finally, by showing how (15)N enrichment at one microsite could be linked to the presence of microbial metabolites, we emphasize the potential of this combined imaging and spectroscopic approach to link microenvironment with geochemical process and/or location with ecological function.
直接观察矿物-有机界面上发生的过程，对于土壤和沉积物中自然土壤有机质和有机污染物的循环越来越重要。具有在亚微米尺度上可视化和表征有机质能力的先进分析工具，如纳米二次离子质谱（NanoSIMS）和与近边 X 射线吸收精细结构光谱学（NEXAFS）相结合的扫描透射 X 射线显微镜（STXM），可用于定位和表征与矿物结合的有机质。利用从温带森林中进行的为期 15 年（15）N 示踪实验中采集的样本，我们证明了 NanoSIMS 具有成像完整土壤颗粒和检测同位素富集点的潜力，即使在（15）N 应用水平较低的情况下也是如此。我们展示了如何通过在同一颗粒上进行的 STXM-NEXAFS 对 NanoSIMS 检测到的同位素富集微区进行分类。最后，通过展示一个微区的（15）N 富集如何与微生物代谢物的存在相关联，我们强调了这种组合成像和光谱方法将微环境与地球化学过程以及/或位置与生态功能联系起来的潜力。
