Characterization of Mercury Reduction by Fe(II) Minerals
EMSL Project ID
30399
Abstract
Mercury is a key contaminant of concern found in Department of Energy sites. Because the chemical form of Hg strongly affects its toxicity and subsurface transport, there is significant interest in understanding the biogeochemical processes that control Hg speciation.Our preliminary laboratory studies with dissimilatory metal reducing bacteria suggest that the reduction of Hg(II) in the presence of iron oxides is catalyzed by a coupled biotic/abiotic pathway involving the reduction of ionic mercury by reactive Fe(II) mineral phases. Here we propose to employ Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to investigate the reactivity of Fe(II) minerals towards ionic mercury. A series of three experiments will be conducted: a) Hg(II) reduction by pure Fe(II) minerals; b) Hg(II) reduction by naturally occurring Fe(II) minerals isolated from DOE sites; and c) Hg(II) reduction by biogenic Fe(II) minerals. Mössbauer spectroscopy will be performed to monitor the oxidation of Fe(II) and the formation of iron oxidation products during reaction with ionic mercury. XRD of reacted samples will be conducted to verify the identity of crystalline Fe(III) mineral phases. TEM and SEM will be performed to image the spatial distribution and particle morphology of iron oxidation mineral products. Finally, XPS will be conducted to determine the presence of Hg(II) and Hg(I) ions adsorbed onto the iron mineral surfaces. The results of this work will provide new insights into the biogeochemical processes that control the release of mercury from contaminated sediments.
This proposed study is a part of a larger research project ("Reduction of mercury in saturated subsurface sediments and its potential to mobilize mercury in its elemental form") currently funded by the DOE Environmental Remediation Sciences Program.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-09-22
End Date
2011-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Shah M, CC Lin, RK Kukkadapu, MH Engelhard, X Zhao, Y Wang, T Barkay, and N Yee. 2013. "Syntrophic Effects in a Subsurface Clostridial Consortium on Fe(III)-(Oxyhydr)oxide Reduction and Secondary Mineralization." Geomicrobiology Journal 31(2):101-115. doi:10.1080/01490451.2013.806610
Wiatrowski HA, S Das, RK Kukkadapu, ES Ilton, T Barkay, and N Yee. 2009. "Reduction of Hg(II) to Hg(0) by Magnetite." Environmental Science & Technology 43(14):5307-5313. doi:10.1021/es9003608