Bäumler R, Weigand H, Mansfeldt T, Schneckenburger D, Wesselbothe S, Marb C (2010)
Publication Language: English
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2010
Publisher: Elsevier
Book Volume: 159
Pages Range: 371-378
DOI: 10.1016/j.geoderma.2010.08.014
Soil surveys have demonstrated arsenic (As) contents of up to 1600mgkg in surface horizons of degraded fens in the Bavarian Molasse basin, Germany. Ground water from the Tertiary aquifer seems to be the primary source of As. Yet, the cause of its accumulation in the topsoil is unclear. Focussing the influence of redox processes on As redistribution, we conducted soil column experiments with the A (716mg Askg), Ag (293mg Askg) and 2Ag (37mg Askg) horizons of a Mollic Gleysol (pH 7.2). The fixed beds were equipped with redox electrodes and suction cups and subjected to a saturation-drainage-saturation cycle. Water table fluctuations were simulated by defined pressure heads applied to the lower column boundaries via a digitally controlled vacuum system. After water saturation, the redox potential (E) dropped to minimum values of around 0mV in the A/Ag and-400mV in the 2Ag horizon. Soil drainage resulted in a quick return to oxidising conditions. Both in the A and Ag horizons total aqueous As concentrations were low (up to 20μgl) and not related to E. In contrast, aqueous As concentrations of the 2Ag horizon were between 5 and 140μgl and increased as the E decreased. However, the As species distribution showed no clear trend with E since both As(III) and As(V) were detected under reducing conditions. High release of As in the 2Ag horizon is consistent with low contents in Fe (hydr)oxides. In the A and Ag horizons, pedogenetic enrichment of sesquioxides contributes to a comparably lower sensitivity of E to water saturation and favours As retention. Thereby, As released under saturated conditions in the 2Ag horizon may be stabilised in the topsoil following capillary rise. Thus, surface horizons may act both as historic and as recent sinks for geogenic As at the site. © 2010 Elsevier B.V.
APA:
Bäumler, R., Weigand, H., Mansfeldt, T., Schneckenburger, D., Wesselbothe, S., & Marb, C. (2010). Arsenic release and speciation in a degraded fen as affected by soil redox potential at varied moisture regime. Geoderma, 159, 371-378. https://doi.org/10.1016/j.geoderma.2010.08.014
MLA:
Bäumler, Rupert, et al. "Arsenic release and speciation in a degraded fen as affected by soil redox potential at varied moisture regime." Geoderma 159 (2010): 371-378.
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