Cable Bacteria Activity Modulates Arsenic Release From Sediments in a Seasonally Hypoxic Marine Basin.

Autor:	van de Velde SJ; Department of Geoscience, Environment and Society, Université Libre de Bruxelles, Brussels, Belgium.; Operational Directorate Natural Environment, Royal Belgian Institute of Natural Sciences, Brussels, Belgium., Burdorf LDW; Microbial Systems Technology, Department of Biology, University of Antwerp, Antwerp, Belgium., Hidalgo-Martinez S; Microbial Systems Technology, Department of Biology, University of Antwerp, Antwerp, Belgium., Leermakers M; Analytical, Environmental and Geo-Chemistry, Department of Chemistry, Vrije Universiteit Brussel, Brussels, Belgium., Meysman FJR; Microbial Systems Technology, Department of Biology, University of Antwerp, Antwerp, Belgium.; Department of Biotechnology, Delft University of Technology, Delft, Netherlands.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2022 Jul 13; Vol. 13, pp. 907976. Date of Electronic Publication: 2022 Jul 13 (Print Publication: 2022).
DOI:	10.3389/fmicb.2022.907976
Abstrakt:	Eutrophication and global change are increasing the occurrence of seasonal hypoxia (bottom-water oxygen concentration <63 μM) in coastal systems worldwide. In extreme cases, the bottom water can become completely anoxic, allowing sulfide to escape from the sediments and leading to the development of bottom-water euxinia. In seasonally hypoxic coastal basins, electrogenic sulfur oxidation by long, filamentous cable bacteria has been shown to stimulate the formation of an iron oxide layer near the sediment-water interface, while the bottom waters are oxygenated. Upon the development of bottom-water anoxia, this iron oxide "firewall" prevents the sedimentary release of sulfide. Iron oxides also act as an adsorption trap for elements such as arsenic. Arsenic is a toxic trace metal, and its release from sediments can have a negative impact on marine ecosystems. Yet, it is currently unknown how electrogenic sulfur oxidation impacts arsenic cycling in seasonally hypoxic basins. In this study, we presented results from a seasonal field study of an uncontaminated marine lake, complemented with a long-term sediment core incubation experiment, which reveals that cable bacteria have a strong impact on the arsenic cycle in a seasonally hypoxic system. Electrogenic sulfur oxidation significantly modulates the arsenic fluxes over a seasonal time scale by enriching arsenic in the iron oxide layer near the sediment-water interface in the oxic period and pulse-releasing arsenic during the anoxic period. Fluxes as large as 20 μmol m -2 day -1 were measured, which are comparable to As fluxes reported from highly contaminated sediments. Since cable bacteria are recognized as active components of the microbial community in seasonally hypoxic systems worldwide, this seasonal amplification of arsenic fluxes is likely a widespread phenomenon. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 van de Velde, Burdorf, Hidalgo-Martinez, Leermakers and Meysman.)
Databáze:	MEDLINE
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