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Divergent Fe and S mineralization pathways during the oxidative transformation of greigite, Fe₃S₄

journal contribution
posted on 2017-09-30, 00:00 authored by Ellen MoonEllen Moon, R T Bush, D H M Gibbs, J P Mata
he iron sulfide mineral greigite, Fe3S4, has previously been identified in the surface layers of the intertidal zone of a partially remediated acid sulfate soil wetland, representing an end-member in an iron sulfide mineralization pathway distinct from that of pyrite. The persistence of greigite is important for the stability of the remediated landscape, but the response of greigite to periods of oxygenation (for example, during a neap tide) is poorly understood. In this study, we employ X-ray absorption spectroscopy to identify the Fe and S speciation and mineralogy resulting from the oxidative disintegration of synthetic greigite under physiochemical solution conditions consistent with a partially remediated acid sulfate soil wetland. Results indicate divergent Fe and S mineralization pathways culminating in elemental sulfur and iron (hyr)oxide minerals. No sulfate-containing minerals were identified, and under all conditions tested, residual greigite remains. The oxidation products, and the presence of sulfur reducing bacteria, provide the right chemical environment for the reformation of greigite during the sub-oxic conditions of the rest of the tidal cycle. This likely explains the persistence of greigite in the intertidal zone, and implies that the oxidation of greigite is not detrimental to the long term stability of the acid sulfate soil remediation process.

History

Journal

Chemical Geology

Volume

468

Pagination

42 - 48

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0009-2541

eISSN

1878-5999

Language

eng

Publication classification

C Journal article; C1.1 Refereed article in a scholarly journal

Copyright notice

2017, Elsevier