Transmission electron microscopy (TEM) is an exceptional and unique tool for the characterization of the size, shape, composition, and crystal structure of nanomaterials. The application of analytical TEM for the characterization of nanoparticles and nanoprocesses in natural and humanâ€impacted environments has been successful, but it is still very limited in wetlands environments. Therefore, in this chapter, we present a synopsis of the capabilities of modern TEM instruments, followed by TEM sample preparations for environmental nanomaterials that are close to wetland materials and conditions. We then show how to study the complex, heterogeneous nature of environmental nanomaterials by including several case studies that are pertinent to future TEMâ€based wetland research. Those are, for example, the discovery and identification of (i) metal sulfide nanocrystals in anaerobic, S†and organicâ€enriched environments, (ii) metal oxide nanocrystals in the surface soils of terrestrial mesocosms, (iii) metal oxide nanoparticles in contaminated floodplains and riverbeds, and (iv) polyphasic schwertmannite, the ferric oxyhydroxysulfate nanomineral, as well as (v) investigations of bacteria–mineral association on metal bioavailability and toxicity. Finally, we conclude the chapter with a discussion of the specifics of wetland science that are amenable to TEM research. We anticipate analytical TEM to provide unique nanoscale observations to future wetland studies.
