CSIRO Publishing blank image blank image blank image blank imageBooksblank image blank image blank image blank imageJournalsblank image blank image blank image blank imageAbout Usblank image blank image blank image blank imageShopping Cartblank image blank image blank image You are here: Journals > Soil Research   
Soil Research
Journal Banner
  Soil, Land Care & Environmental Research
 
blank image Search
 
blank image blank image
blank image
 
  Advanced Search
   

Journal Home
About the Journal
Editorial Structure
Contacts
For Advertisers
Content
Online Early
Current Issue
Just Accepted
All Issues
Special Issues
Sample Issue
For Authors
General Information
Scope
Submit Article
Author Instructions
Open Access
For Referees
Referee Guidelines
Review an Article
Annual Referee Index
For Subscribers
Subscription Prices
Customer Service
Print Publication Dates

blue arrow e-Alerts
blank image
Subscribe to our Email Alert or RSS feeds for the latest journal papers.

red arrow Connect with us
blank image
facebook twitter LinkedIn

Now Online

Land Resources Surveys


 

Article << Previous     |     Next >>   Contents Vol 42(4)

The process of sulfide oxidation in some acid sulfate soil materials

N. J. Ward, L. A. Sullivan, D. M. Fyfe, R.T. Bush and A. J. P. Ferguson

Australian Journal of Soil Research 42(4) 449 - 458
Published: 25 June 2004

Abstract

The process of sulfide oxidation in acid sulfate soils (ASS) is complex, involving the formation of numerous oxidation products. In this study the sulfide oxidation process was examined in 2 ASS materials over a period of 36 days using laboratory incubation experiments. Both ASS materials experienced substantial sulfide oxidation and acidification during incubation. The oxidation of pyrite was the primary cause of acidification in these ASS materials. Although a decrease in magnetic susceptibility (χ) over the initial 4 days of incubation suggested the rapid oxidation of ferromagnetic iron monosulfide greigite (Fe3S4), the total acid volatile sulfur (SAV) fraction increased in concentration by an order of magnitude over the initial 8 days of incubation. Oxygen (O2) concentration profiles indicated the presence of anoxic conditions in the centre of the incubating materials even after 16 days of exposure to the atmosphere enabling SAV formation to occur. The oxidation of the SAV fraction did not result in substantial acidification. A large proportion of the water-soluble iron released by sulfide oxidation was precipitated as iron oxides and hydroxides. Sulfate (SO42–) was the dominant sulfur species produced from sulfide oxidation in both ASS materials, although water-soluble SO42– was a poor indicator of the extent of sulfide oxidation. The sulfoxyanion intermediates, thiosulfate (S2O32–) and tetrathionate (S4O62–), were detected only in the early stages of incubation, with minimal amounts being detected after the initial 4 days. The relative abundance of these 2 intermediate sulfur species appeared to be dependent on the soil pH, with S4O62– dominating S2O32– in the more acidic ASS material (i.e. pH <6) as has been observed in previous studies. The diminishing presence of sulfoxyanion intermediates as oxidation progressed was indicative that ferric ion (Fe3+) and bacterial catalysis were driving the oxidation processes. While these sulfoxyanion intermediates only constituted a small percentage of the reduced inorganic sulfur (RIS) fraction, they accounted for up to 9.3% of the total soluble sulfur fraction. Elemental sulfur (S0) was not an important sulfide oxidation product in the ASS materials examined in this study.

Keywords: pyrite oxidation, acidification, chromium reducible sulfur, acid volatile sulfur, thiosulfate, tetrathionate, soil incubation.



Full text doi:10.1071/SR03135

© CSIRO 2004

blank image
Subscriber Login
Username:
Password:  

 
PDF (363 KB) $25
 Export Citation
 Print
  
    
Legal & Privacy | Contact Us | Help

CSIRO

© CSIRO 1996-2015