Details

Autor(en) / Beteiligte

• Kölbl, Angelika
• Kaiser, Klaus
• Winkler, Pauline
• Mosley, Luke
• Fitzpatrick, Rob
• Marschner, Petra
• Wagner, Friedrich E.
• Häusler, Werner
• Mikutta, Robert

Titel

Transformation of jarosite during simulated remediation of a sandy sulfuric soil

Ist Teil von

• The Science of the total environment, 2021-06, Vol.773, p.145546-145546, Article 145546

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• Aeration of wetland soils containing iron (Fe) sulfides can cause strong acidification due to the generation of large amounts of sulfuric acid and formation of Fe oxyhydroxy sulfate phases such as jarosite. Remediation by re-establishment of anoxic conditions promotes jarosite transformation to Fe oxyhydroxides and/or Fe sulfides, but the driving conditions and mechanisms are largely unresolved. We investigated a sandy, jarosite-containing soil (initial pH = 3.0, Eh ~600 mV) in a laboratory incubation experiment under submerged conditions, either with or without wheat straw addition. Additionally, a model soil composed of synthesized jarosite mixed with quartz sand was used. Eh and pH values were monitored weekly. Solution concentrations of total dissolved organic carbon, Fe, S, and K as well as proportions of Fe2+ and SO42− were analysed at the end of the experiment. Sequential Fe extraction, X-ray diffraction, and Mössbauer spectroscopy were used to characterize the mineral composition of the soils. Only when straw was added to natural and artificial sulfuric soils, the pH increased up to 6.5, and Eh decreased to approx. 0 mV. The release of Fe (mainly Fe2+), K, and S (mainly SO42−) into the soil solution indicated redox- and pH-induced dissolution of jarosite. Mineralogical analyses confirmed jarosite losses in both soils. While lepidocrocite formed in the natural sulfuric soil, goethite was formed in the artificial sulfuric soil. Both soils showed also increases in non-sulfidized, probably organically associated Fe2+/Fe3+, but no (re-)formation of Fe sulfides. Unlike Fe sulfides, the formed Fe oxyhydroxides are not prone to support re-acidification in the case of future aeration. Thus, inducing moderately reductive conditions by controlled supply of organic matter could be a promising way for remediation of soils and sediments acidified by oxidation of sulfuric materials. [Display omitted] •Straw supply induced reduction processes and pH increase in submerged sulfuric soils.•Both reducing conditions and pH increase contributed to dissolution of jarosite.•Fe3+ was partly reduced but SO42− reduction was little during 15-week incubation.•No sulfides, but FeIII oxyhydroxides and Fe2+/Fe3+–organic matter associates formed.•Prior pH adjustment is not necessary for remediation of a sandy sulfuric soil.