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Groundwater derived arsenic in high carbonate wetland soils: Sources, sinks, and mobility

Title data

Bauer, Markus ; Fulda, Beate ; Blodau, Christian:
Groundwater derived arsenic in high carbonate wetland soils: Sources, sinks, and mobility.
In: Science of the Total Environment. Vol. 401 (2008) Issue 1-3 . - pp. 109-120.
ISSN 1879-1026
DOI: https://doi.org/10.1016/j.scitotenv.2008.03.030

Abstract in another language

Wetlands and organic soils have been recognized as important sinks for arsenic in the environment, yet sources and immobilization mechanisms of As are often unclear. To begin rectifying this deficiency, we investigated As retention and binding mechanisms at a degraded, minerotrophic wetland site in contact with groundwater rich in As and Fe. Arsenic occurred in high dissolved concentrations of up to 467 μg L− 1 in the groundwater, but dropped to values below 10 μg L− 1 towards the surface. The solid phase As content instead was high in the topsoil with up to 3400 mg kg− 1 and decreased with depth to 15 mg kg− 1. A similar pattern was observed with respect to Fe. Amorphous and crystalline iron precipitates were the main sorbents for arsenic in the soil horizons according to results from wet chemical sequential extractions. Arsenic was apparently not associated with inorganic carbon phases, but a substantial portion of up to 31% of Astot could be mobilized by dispersion of soil organic matter. Ratios of dissolved As(III)/As(V) decreased from the deeper As(III) dominated groundwater to the As(V) dominated soil porewaters, where As was apparently immobilized in its oxidized form. Concentrations of the organic species DMA and MMA were negligible. According to the results of simple one-dimensional estimates the vertical arsenic transport from the source in the groundwater to the topsoil was slow given an extrapolation of current conditions. These results suggest that As accumulation started before the beginning of drainage in the now degraded peatland soils and the degradation and mass loss of organic matter under oxic conditions caused the very high As concentrations found in the topsoil horizon today.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER61937
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Hydrology
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Research Institutions > Research Units > Limnological Research Station
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
Research Institutions > Research Units
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 15 May 2015 14:47
Last Modified: 15 May 2015 14:47
URI: https://eref.uni-bayreuth.de/id/eprint/13721