Elucidating soil structural associations of organic material with nano-scale secondary ion mass spectrometry (NanoSIMS)

摘要

The specific features of the nano-scale secondary ion mass spectrometry (nanoSIMS) technology with the simultaneous analysis of up to seven ions species with high sensitivity and resolution enables us to perform multi-element and isotope measurementsat the submicron-scale. In order to demonstrate the power of this technique, we performed an incubation experiment with primary soil particles of the fine silt and clay fraction and soil aggregates (< 6.3 mu m) from an Albic Luvisol and a Haplic Chernozem, respectively, with a ~(13)C and ~(15)N labelled amino acid mixture as tracer. Before and at selected time intervals after addition of the tracer, samples were derived and prepared for nanoSIMS investigation. For this purpose, different sample pre-treatments for single soil particles and soil aggregates were developed. Primary soil particles high in carbon showed an enrichment of ~(13)C and ~(15)N after label addition which decreases over time. In soil aggregates, nanoSIMS analyses revealed that the labelled amino acids were transported most likely by diffusion through the pores of the aggregate from the outside to its interior. From these first results, it can be concluded that the nanoSIMS technology will allow a major step forward in the understanding of biogeochemical processes and properties of soil.