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Dynamics of organic and inorganic arsenic in the solution phase of an acidic fen in Germany

Title data

Huang, Jen-How ; Matzner, Egbert:
Dynamics of organic and inorganic arsenic in the solution phase of an acidic fen in Germany.
In: Geochimica et Cosmochimica Acta. Vol. 70 (2006) Issue 8 . - pp. 2023-2033.
ISSN 0016-7037
DOI: https://doi.org/10.1016/j.gca.2006.01.021

Abstract in another language

Wetland soils play a key role for the transformation of heavy metals in forested watersheds, influencing their mobility, and ecotoxicity. Our goal was to investigate the mechanisms of release from solid to solution phase, the mobility, and the transformation of arsenic species in a fen soil. In methanol–water extracts, monomethylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, arsenobetaine, and two unknown organic arsenic species were found with concentrations up to 14 ng As g−1 at the surface horizon. Arsenate is the dominant species at the 0–30 cm depth, whereas arsenite predominated at the 30–70 cm depth. Only up to 2.2% of total arsenic in fen was extractable with methanol–water. In porewaters, depth gradient spatial variation of arsenic species, pH, redox potentials, and the other chemical parameters along the profile was observed in June together with high proportion of organic arsenic species (up to 1.2 μg As L−1, 70% of total arsenic). Tetramethylarsonium ion and an unknown organic arsenic species were additionally detected in porewaters at deeper horizons. In comparison, the arsenic speciation in porewaters in April was homogeneous with depth and no organic arsenic species were found. Thus, the occurrence of microbial methylation of arsenic in fen was demonstrated for the first time. The 10 times elevated total arsenic concentrations in porewaters in June compared to April were accompanied by elevated concentrations of total iron, lower concentrations of sulfate and the presence of ammonium and phosphate. The low proportion of methanol–water extractable total arsenic suggests a generally low mobility of arsenic in fen soils. The release of arsenic from solid to solution phases in fen is dominantly controlled by dissolution of iron oxides, redox transformation, and methylation of arsenic, driven by microbial activity in the growing season. As a result, increased concentrations of total arsenic and potentially toxic arsenic species in fen porewaters were found in the growing season, suggesting an enhancing risk of arsenic transport of ground- and surface-waters under these conditions.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER31952
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Soil Ecology
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Former Professors > Chair Soil Ecology - Univ.-Prof. Dr. Egbert Matzner
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 11 Sep 2015 06:33
Last Modified: 11 Sep 2015 06:33
URI: https://eref.uni-bayreuth.de/id/eprint/19168