Mineral weathering at the grain-microbe interface is driven by biological processes that include biophysical degradation and biochemical dissolution of mineral particles [1-3]. Microorganisms actively support terrestrial ecosystems by extracting and transferring rock-derived nutrients via direct and indirect biological weathering mechanisms. However, fundamental knowledge gaps exist in characterizing biogeochemical processes that transform microbe-mineral interfaces at submicron scales, particularly in natural settings (i.e., in Earth’s critical zone, from the tree tops to the bedrock where meteoric waters have influence).
The objective of this research is to use a correlative bimodal high-resolution microscopy technique, helium ion microscopy (HIM) in conjunction with scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDS), to detect and assess potential biogeochemical drivers of mineral weathering in natural settings. Nylon mesh bags of different sizes (coarse - 35 μm, and fine - 0.5 μm) were filled with pristine basalt, granite, and quartz grains (53-250 μm) and deployed in surface soils (0-10 cm) of contrasting ecosystems (semiarid to humid) for up to three years. The mesh bags were designed to include (35 μm) and exclude (0.5 μm) direct fungal hyphae and microbial contact with mineral surfaces. Both mesh sizes allow for solute and nanosize solid interactions with deployed mineral grains.
Qafoku, Odeta, Rebecca A. Lybrand, Vaithiyalingam Shutthanandan, Rachel E. Gallery, Jason C. Austin, Paul A. Schroeder, Jennifer Fedenko, Erin Rooney, and Dragos G. Zaharescu (2019): A correlative bimodal surface imaging method to assess hyphae-rock interactions. Microscopy and Microanalysis, 25(S2), 2436-2437.