Sulfate Reduction Accelerates Groundwater Arsenic Contamination Even in Aquifers with Abundant Iron Oxides

Overview

Journal Nat Water

Date 2023 Apr 10

PMID 37034542

Authors

Athena A Nghiem

Henning Prommer

M Rajib H Mozumder

Adam Siade

James Jamieson

Kazi Matin Ahmed

Alexander van Geen

Benjamin C Bostick

Affiliations

Soon will be listed here.

Abstract

Groundwater contamination by geogenic arsenic is a global problem affecting nearly 200 million people. In South and Southeast Asia, a cost-effective mitigation strategy is to use oxidized low-arsenic aquifers rather than reduced high-arsenic aquifers. Aquifers with abundant oxidized iron minerals are presumably safeguarded against immediate arsenic contamination, due to strong sorption of arsenic onto iron minerals. However, preferential pumping of low-arsenic aquifers can destabilize the boundaries between these aquifers, pulling high-arsenic water into low-arsenic aquifers. We investigate this scenario in a hybrid field-column experiment in Bangladesh where naturally high-arsenic groundwater is pumped through sediment cores from a low-arsenic aquifer, and detailed aqueous and solid-phase measurements are used to constrain reactive transport modelling. Here we show that elevated groundwater arsenic concentrations are induced by sulfate reduction and the predicted formation of highly mobile, poorly sorbing thioarsenic species. This process suggests that contamination of currently pristine aquifers with arsenic can occur up to over 1.5 times faster than previously thought, leading to a deterioration of urgently needed water resources.

Citing Articles

Microbes take the 'forever' out of 'forever chemicals'.

Nature. 2023; 618(7963):11.

PMID: 37225815 DOI: 10.1038/d41586-023-01697-4.

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