Universität zu Köln

Schuth, Stephan and Mansfeldt, Tim (2016). Iron isotope composition of aqueous phases of a lowland environment. Environ. Chem., 13 (1). S. 89 - 102. CLAYTON: CSIRO PUBLISHING. ISSN 1449-8979

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Abstract

Environmental context Iron (Fe) isotope analysis is a powerful tool to understand the transport of Fe within and from soils to rivers. We determined Fe isotopes and Fe concentrations of soil solutions at different depths and found that the Fe isotope compositions are modified owing to adsorption onto Fe oxides, especially in the subsoil. Hence Fe-rich capillary rising groundwater or seeping Fe-rich surface water are depleted in Fe and potentially other metals in Fe oxide-rich soil horizons. Abstract The mobility of iron (Fe) in soils is strongly affected by redox conditions, which also affect Fe input into groundwater and rivers. Stable Fe isotope analyses allow further investigation of Fe translocation processes within, into and out of soils. Soil solutions taken from a Gleysol in a lowland area (NW Germany) at different depths revealed that Fe concentration and isotope ratios strongly varied with abundance of solid Fe oxides. Low Fe-56 values of -1.7 parts per thousand and minimum Fe concentrations of similar to 0.2mgL(-1) were recorded in soil solutions of Fe-rich horizons. Soil solutions of a Fe-poor horizon, however, yielded higher Fe-56 values (-0.39 parts per thousand) and Fe concentrations of up to 68mgL(-1). The water of an adjacent drainage ditch featured Fe-56 values of -1.1 parts per thousand, in strong contrast to +0.60 parts per thousand of short-range ordered Fe oxide deposits in the ditch bed. We attribute the coupled low Fe-56 values and Fe concentrations to combined adsorption and atom exchange between dissolved Fe and Fe oxides. Consequently Fe oxide-poor horizons had higher Fe-56 values and dissolved Fe concentrations. Outflow of Fe-rich groundwater and surface water during rainfall into rivers is responsible for high Fe-56 for Fe-oxide precipitates and low riverine Fe-56 values.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schuth, Stephan UNSPECIFIED UNSPECIFIED UNSPECIFIED Mansfeldt, Tim UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-291850
DOI:	10.1071/EN15073
Journal or Publication Title:	Environ. Chem.
Volume:	13
Number:	1
Page Range:	S. 89 - 102
Date:	2016
Publisher:	CSIRO PUBLISHING
Place of Publication:	CLAYTON
ISSN:	1449-8979
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NATURAL ORGANIC-MATTER; FERROUS IRON; ATOM EXCHANGE; FE(II)-FE(III) ELECTRON; MOSSBAUER-SPECTROSCOPY; DISSIMILATORY FE(III); MICROBIAL REDUCTION; REDOX OSCILLATIONS; IRON(III) OXIDES; FRACTIONATION Multiple languages Chemistry, Analytical; Environmental Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/29185