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Arsenic Fate in Peat Controlled by the pH-Dependent Role of Reduced Sulfur

Title data

Eberle, Anne ; Besold, Johannes ; Kerl, Carolin F. ; Lezama-Pacheco, Juan S. ; Fendorf, Scott ; Planer-Friedrich, Britta:
Arsenic Fate in Peat Controlled by the pH-Dependent Role of Reduced Sulfur.
In: Environmental Science & Technology. Vol. 54 (April 2020) Issue 11 . - pp. 6682-6692.
ISSN 0013-936X
DOI: https://doi.org/10.1021/acs.est.0c00457

Abstract in another language

Reduced sulfur (S) has a contrasting role on the fate of arsenic (As) in peatlands. Sulfur bridges provide efficient binding of As to organic carbon (C), but formation of aqueous As-S species, so-called thioarsenates, leads to low to no sorption tendency to organic C functional groups. Here, we studied how pH changes the role of reduced S for desorption and retention of pre-sorbed As in model peat. Control desorption experiments without S addition revealed that As was mobilized, predominantly as arsenite, in all treatments with relative mobilization increasing with pH (4.5<7.0<8.5). Addition of sulfide or polysulfide caused substantial As retention at acidic conditions, but significantly enhanced As desorption compared to controls at neutral to alkaline pH. Thioarsenates dominated As speciation at pH 7.0 and 8.5 (maximum 79%) and remained in solution without (re)sorption to peat. Predominance of arsenite in control experiments and no evidence of surface-bound thioarsenates at pH 7.0, suggest mobilization to proceed via arsenite desorption, reaction with dissolved or surface-bound reduced S, and formation of thioarsenates. Our results suggest that natural or management-related increases in pH or increases in reduced S in near-neutral pH environments can turn organic matter from an As sink into a source.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Environmental Geochemistry Group
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Environmental Geochemistry Group > Professor Environmental Geochemistry - Univ.-Prof. Dr. Britta Planer-Friedrich
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 > 500 Natural sciences
500 Science > 550 Earth sciences, geology
Date Deposited: 28 May 2020 07:19
Last Modified: 03 Jun 2020 11:29
URI: https://eref.uni-bayreuth.de/id/eprint/55298