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Redox Heterogeneities Promote Thioarsenate Formation and Release into Groundwater from Low Arsenic Sediments

Titelangaben

Kumar, Naresh ; Noël, Vincent ; Planer-Friedrich, Britta ; Besold, Johannes ; Lezama-Pacheco, Juan ; Bargar, John R. ; Brown, Gordon E. ; Fendorf, Scott ; Boye, Kristin:
Redox Heterogeneities Promote Thioarsenate Formation and Release into Groundwater from Low Arsenic Sediments.
In: Environmental Science & Technology. Bd. 54 (2020) Heft 6 . - S. 3237-3244.
ISSN 0013-936X
DOI: https://doi.org/10.1021/acs.est.9b06502

Abstract

Groundwater contamination by As from natural and anthropogenic sources is a world-wide concern. Redox heterogeneities over space and time are common and can influence the molecular-level speciation of As, and thus As release/retention, but are largely unexplored. Here we present results from a dual-domain column experiment, with natural organic-rich, fine-grained, and sulfidic sediments embedded as lenses (referred to as ‘reducing lenses’) within natural aquifer sand. We show that redox interfaces in sulfur-rich, alkaline aquifers may release concerning levels of As, even when sediment As concentration is low (<2 mg/kg), due to the formation of mobile thioarsenates at aqueous sulfide:Fe molar ratios <1. In our experiments, this behavior occurred in the aquifer sand between reducing lenses and was attributed to the spreading of sulfidic conditions and subsequent Fe reductive dissolution. In contrast, inside reducing lenses (and some locations in the aquifer) the aqueous sulfide:Fe molar ratios exceeded 1 and aqueous sulfide:As molar ratios exceeded 100, which partitioned As(III)-S to the solid phase (associated with organics or as realgar (As4S4)). These results highlight the importance of thioarsenates in natural sediments and indicate that redox interfaces and sediment heterogeneities could locally degrade groundwater quality, even in aquifers with unconcerning solid phase As concentrations.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Professur Umweltgeochemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Professur Umweltgeochemie > Professur Umweltgeochemie - Univ.-Prof. Dr. Britta Planer-Friedrich
Forschungseinrichtungen > Zentrale wissenschaftliche Einrichtungen > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften
Forschungseinrichtungen
Forschungseinrichtungen > Zentrale wissenschaftliche Einrichtungen
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften
500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
Eingestellt am: 28 Mai 2020 07:08
Letzte Änderung: 12 Jul 2023 07:10
URI: https://eref.uni-bayreuth.de/id/eprint/55295