Arsenic behavior in groundwater in Hanoi (Vietnam) influenced by a complex biogeochemical network of iron, methane, and sulfur cycling

Martyna Glodowska; Emiliano Stopelli; Daniel Straub; Duyen Vu Thi; Pham T K Trang; Pham H Viet; AdvectAs Team Members; Michael Berg; Andreas Kappler; Sara Kleindienst

doi:10.1016/j.jhazmat.2020.124398

Arsenic behavior in groundwater in Hanoi (Vietnam) influenced by a complex biogeochemical network of iron, methane, and sulfur cycling

J Hazard Mater. 2021 Apr 5:407:124398. doi: 10.1016/j.jhazmat.2020.124398. Epub 2020 Oct 29.

Authors

Affiliations

¹ Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Germany; Microbial Ecology, Center for Applied Geosciences, University of Tübingen, Germany.
² Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
³ Microbial Ecology, Center for Applied Geosciences, University of Tübingen, Germany; Quantitative Biology Center (QBiC), University of Tübingen, Germany.
⁴ Key Laboratory of Analytical Technology for Environmental Quality and Food Safety (KLATEFOS), VNU University of Science, Vietnam National University, Hanoi, Vietnam.
⁵ AdvectAs members-listed in the SI.
⁶ Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; UNESCO Chair on Groundwater Arsenic within the 2030 Agenda for Sustainable Development, School of Civil Engineering and Surveying, University of Southern Queensland, Australia.
⁷ Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Germany.
⁸ Microbial Ecology, Center for Applied Geosciences, University of Tübingen, Germany; Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland. Electronic address: sara.kleindienst@uni-tuebingen.de.

PMID: 33213979
DOI: 10.1016/j.jhazmat.2020.124398

Abstract

The fate of arsenic (As) in groundwater is determined by multiple interrelated microbial and abiotic processes that contribute to As (im)mobilization. Most studies to date have investigated individual processes related to As (im)mobilization rather than the complex networks present in situ. In this study, we used RNA-based microbial community analysis in combination with groundwater hydrogeochemical measurements to elucidate the behavior of As along a 2 km transect near Hanoi, Vietnam. The transect stretches from the riverbank across a strongly reducing and As-contaminated Holocene aquifer, followed by a redox transition zone (RTZ) and a Pleistocene aquifer, at which As concentrations are low. Our analyses revealed fermentation and methanogenesis as important processes providing electron donors, fueling the microbially mediated reductive dissolution of As-bearing Fe(III) minerals and ultimately promoting As mobilization. As a consequence of high CH₄ concentrations, methanotrophs thrive across the Holocene aquifer and the redox transition zone. Finally, our results underline the role of SO₄^2--reducing and putative Fe(II)-/As(III)-oxidizing bacteria as a sink for As, particularly at the RTZ. Overall, our results suggest that a complex network of microbial and biogeochemical processes has to be considered to better understand the biogeochemical behavior of As in groundwater.

Keywords: Arsenic cycling; Fermentation; Groundwater hydrochemistry; Methanogenesis; Methanotrophy; Microbial processes; Sulfate reduction.

Publication types

Research Support, Non-U.S. Gov't