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Carbon and methane cycling in arsenic-contaminated aquifers

Stopelli, Emiliano; Duyen, Vu T.; Prommer, Henning; Glodowska, Martyna; Kappler, Andreas; Schneider, Magnus 1; Eiche, Elisabeth 1; Lightfoot, Alexandra K.; Schubert, Carsten J.; Trang, Pham K. T.; Viet, Pham H.; Kipfer, Rolf; Winkel, Lenny H. E.; Berg, Michael
1 Institut für Angewandte Geowissenschaften (AGW), Karlsruher Institut für Technologie (KIT)


Geogenic arsenic (As) contamination of groundwater is a health threat to millions of people worldwide, particularly in alluvial regions of South and Southeast Asia. Mitigation measures are often hindered by high heterogeneities in As concentrations, the cause(s) of which are elusive. Here we used a comprehensive suite of stable isotope analyses and hydrogeochemical parameters to shed light on the mechanisms in a typical high-As Holocene aquifer near Hanoi where groundwater is advected to a low-As Pleistocene aquifer. Carbon isotope signatures (δ$^{13}$C-CH$_{4}$, δ$^{13}$C-DOC, δ$^{13}$C-DIC) provided evidence that fermentation, methanogenesis and methanotrophy are actively contributing to the As heterogeneity. Methanogenesis occurred concurrently where As levels are high (>200 µg/L) and DOC-enriched aquitard pore water infiltrates into the aquifer. Along the flowpath to the Holocene/Pleistocene aquifer transition, methane oxidation causes a strong shift in δ$^{13}$C-CH$_{4}$ from -87‰ to +47‰, indicating high reactivity. These findings demonstrate a previously overlooked role of methane cycling and DOC infiltration in high-As aquifers.

Verlagsausgabe §
DOI: 10.5445/IR/1000133699
Veröffentlicht am 08.06.2021
DOI: 10.1016/j.watres.2021.117300
Zitationen: 22
Zitationen: 25
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 15.07.2021
Sprache Englisch
Identifikator ISSN: 0043-1354
KITopen-ID: 1000133699
Erschienen in Water research
Verlag Elsevier
Band 200
Seiten Art. Nr.: 117300
Schlagwörter Groundwater quality, Drinking water, Geogenic As contamination, Heterogeneity, Organic matter, Carbon isotope δ13 C
Nachgewiesen in Scopus
Web of Science
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