Nano and Bulk-Scale Characterization of Biogeochemical Processes: A Case Study

Veeramani, H. and Hochella, M. F. (2013) Nano and Bulk-Scale Characterization of Biogeochemical Processes: A Case Study. In: Goldschmidt 2013, Florence, Italy, 25-30 Aug 2013,

Abstract

Recent advances in nanotechnology and analytic instrumentation allow biogeochemical processes between microbes, metals and minerals to be probed at remarkable levels of complexity, sensitivity, space and time. One of the dominant trends in geomicrobiology is the detailed characterization and application of biogenic minerals whose characteristic features are at the nanometer scale in at least one dimension. It is therefore important to understand – and ultimately exploit – the unique properties and behavior of a wide range of nanoscale biogenic materials. Central to this trend are the development and application of effective analytic techniques for characterizing the structural and chemical properties of biogenic minerals with (sub)nanometer spatial resolution. Microbes in the subsurface are involved, directly or indirectly, in a plethora of activities such as metal reduction and oxidation, mineral precipitation and dissolution. These innate capacities of subsurface microbes are often exploited for in situ remediation of contaminated sites. During subsurface bioremediation of uranium-contaminated sites, indigenous metal and sulfate-reducing bacteria may produce biogenic minerals such as mackinawite (FeS) which could potentially drive abiotic uranium reduction. In this work, the propensity of well-characterized biogenic mackinawite to abiotically reduce U(VI) was tested using a suite of electron microscopy and synchrotron based spectroscopy techniques. High-resolution electron microscopy confirmed the formation of nanoparticulate uraninite [UO2] on the surface of biogenic mackinawite, which was further confirmed with bulk X-ray absorption spectroscopy that revealed the molecular coordination environment of uraninite. X-ray photoelectron spectroscopy confirms that U(IV) reduction was coupled to the oxidation of S2- and not structural Fe(II) within the biogenic mackinawite. The combination of rigorous nano- and bulk-scale characterization provides insights into such biogeochemical processes, that occur during subsurface biostimulation, that are not always possible with bulk-scale analyses alone.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Veeramani, Dr Harish
• Authors: Veeramani, H., and Hochella, M. F.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment