Universität zu Köln

Dorau, Kristof ORCID: 0000-0002-1815-1929 and Mansfeldt, Tim (2015). Manganese-Oxide-Coated Redox Bars as an Indicator of Reducing Conditions in Soils. J. Environ. Qual., 44 (2). S. 696 - 704. MADISON: AMER SOC AGRONOMY. ISSN 1537-2537

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Abstract

Identification of reducing conditions in soils is of concern not only for pedogenesis but also for nutrient and pollutant dynamics. We manufactured manganese (Mn)-oxide-coated polyvinyl chloride bars and proved their suitability for the identification of reducing soil conditions. Birnessite was synthesized and coated onto white polyvinyl chloride bars. The dark brown coatings were homogenous and durable. As revealed by microcosm devices with adjusted redox potentials (E-H), under oxidizing conditions (E-H similar to 450 mV at pH 7) there was no Mn-oxide removal. Reductive dissolution of Mn-oxides, which is expressed by the removal of the coatings, started under weakly reducing conditions (E-H similar to 175 mV) and was more intensive under moderately reducing conditions (similar to 80 mV). According to thermodynamics, the removal of Mn-oxide coatings (225 mm(2) d(-1)) exceeded the removal of iron (Fe)-oxide coatings (118 mm(2) d(-1)) in soil column experiments. This was confirmed in a soil with a shallow and strongly fluctuating water table where both types of redox bars were inserted. Consequently, it was possible to identify reducing conditions in soils using Mn-oxide-coated bars. We recommend this methodology for short-term monitoring because tri- and tetravalent Mn is the preferred electron acceptor compared with trivalent Fe, and this additionally offers the possibility of distinguishing between weakly and moderately reducing conditions. If dissolved Fe2+ is abundant in soils, the possibility of nonenzymatic reduction of Mn has to be taken into account.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Dorau, Kristof UNSPECIFIED orcid.org/0000-0002-1815-1929 UNSPECIFIED Mansfeldt, Tim UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-405946
DOI:	10.2134/jeq2014.03.0140
Journal or Publication Title:	J. Environ. Qual.
Volume:	44
Number:	2
Page Range:	S. 696 - 704
Date:	2015
Publisher:	AMER SOC AGRONOMY
Place of Publication:	MADISON
ISSN:	1537-2537
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WATERLOGGED SOIL; IRON-OXIDES; BIRNESSITE; REDUCTION; FIELD; IRIS; PH; TRANSFORMATION; TEMPERATURE; EXCHANGE Multiple languages Environmental Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/40594