Sea level rise from climate change is expected to increase the release of arsenic into Bangladesh's drinking well water by reduction and by the salt effect

Seth H Frisbie; Erika J Mitchell; Azizur R Molla

doi:10.1371/journal.pone.0295172

Sea level rise from climate change is expected to increase the release of arsenic into Bangladesh's drinking well water by reduction and by the salt effect

PLoS One. 2024 Jan 17;19(1):e0295172. doi: 10.1371/journal.pone.0295172. eCollection 2024.

Authors

Seth H Frisbie¹, Erika J Mitchell², Azizur R Molla³

Affiliations

¹ Department of Chemistry and Biochemistry, Norwich University, Northfield, VT, United States of America.
² Better Life Laboratories, Incorporated, East Calais, VT, United States of America.
³ Department of Public Health, Grand Valley State University, Grand Rapids, MI, United States of America.

Abstract

Background: Over 165,000,000 people live in Bangladesh; approximately 97% of Bangladeshis drink well water. Approximately 49% of Bangladesh's area has drinking well water with arsenic (As) concentrations that exceed the 10 micrograms per liter (μg/L) World Health Organization (WHO) guideline. This exposure to a potent carcinogen is a significant threat to public health. About 21% of Bangladesh is flooded each year during a typical monsoon season. As climate change progresses, sea levels will continue to rise, and the area and duration of these annual floods will increase. We hypothesize that these consequences of climate change can increase the release of arsenic from sediments into Bangladesh's drinking well water.

Methods: Drinking well water samples were collected during a national-scale survey in Bangladesh. The dissolved oxygen concentration, oxidation-reduction potential, specific conductance, pH, and temperature were measured at sampling with calibrated portable electronic sensors. The arsenic concentration was measured by the silver diethyldithiocarbamate method.

Results: As the concentration of dissolved oxygen decreases, the concentration of arsenic increases (p-value = 0.0028). Relatedly, as the oxidation-reduction potential decreases, the concentration of arsenic increases (p-value = 1.3×10-5). This suggests that arsenic is released from sediments into Bangladesh's drinking well drinking water by reduction. As the specific conductance increases, the concentration of arsenic increases (p-value = 0.023). This suggests that arsenic is also released from sediments into water by the salt effect.

Conclusions: Rising sea levels can cause a decrease in the dissolved oxygen concentration and oxidation-reduction potential of the underlying aquifer; this should increase the dissolution of insoluble arsenate (H3-xAs(V)O4x-) in sediments by reduction. This, in turn, should release soluble arsenite (H3-xAs(III)O3x-) into the drinking well water. Rising sea levels can cause an increase in the salt concentration of the underlying aquifer; this should increase the release of arsenic from sediments into the drinking well water by the salt effect.

Copyright: © 2024 Frisbie et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

MeSH terms

Arsenic* / analysis
Bangladesh
Climate Change
Drinking Water*
Humans
Oxygen
Sea Level Rise
Water Pollutants, Chemical* / analysis

Substances

Arsenic
Water Pollutants, Chemical
Drinking Water
Oxygen

Grants and funding

The fieldwork in Bangladesh was funded by the United States Agency of International Development (USAID; contract number US AID RE III 388-0070; https://www.usaid.gov/). This fieldwork began in July of 1997 and ended in August of 1997. USAID is an international development agency that is funded by the United States government. USAID employed Seth H. Frisbie (SHF) and paid his salary during these two months in 1997. After August 1997, SHF received no specific funding for this work. Erika J. Mitchell (EJM) and Azizur R. Molla (ARM) received no specific funding for this work. No commercial companies funded the study or the authors. All other costs have been paid from the personal savings of the authors. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.