Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes

I. Mihajlov, M. Stute, Peter Schlosser, B. J. Mailloux, Y. Zheng, I. Choudhury, K. M. Ahmed, A. van Geen

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

More than 100,000 community wells have been installed in the 150–300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 µg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35–240 m depth range was sampled for tritium (3H), oxygen and hydrogen isotopes of water (18O/16O and 2H/1H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14C/12C and 13C/12C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon (14C) ages in DIC range from modern to 10 kyr. In the 90–240 m depth range, however, only five wells shallower than 150 m contain detectable 3H (<0.3 TU) and 14C ages of DIC cluster around 10 kyr. The radiogenic helium (4He) content in groundwater increases linearly across the entire range of 14C ages at a rate of 2.5 × 10−12 ccSTP 4He g−1 yr−1. Within the samples from depths >90 m, systematic relationships between 18O/16O, 2H/1H, 13C/12C, and 14C/12C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer.

Original languageEnglish (US)
Pages (from-to)3324-3349
Number of pages26
JournalWater Resources Research
Volume52
Issue number5
DOIs
StatePublished - May 1 2016
Externally publishedYes

Fingerprint

arsenic
recharge
aquifer
isotope
well
noble gas
vegetation cover
monsoon
drinking water
Holocene
temperature
water

Keywords

  • arsenic
  • Bangladesh
  • groundwater dating
  • noble gas temperatures
  • radiocarbon
  • tritium

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes. / Mihajlov, I.; Stute, M.; Schlosser, Peter; Mailloux, B. J.; Zheng, Y.; Choudhury, I.; Ahmed, K. M.; van Geen, A.

In: Water Resources Research, Vol. 52, No. 5, 01.05.2016, p. 3324-3349.

Research output: Contribution to journalArticle

Mihajlov, I. ; Stute, M. ; Schlosser, Peter ; Mailloux, B. J. ; Zheng, Y. ; Choudhury, I. ; Ahmed, K. M. ; van Geen, A. / Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes. In: Water Resources Research. 2016 ; Vol. 52, No. 5. pp. 3324-3349.
@article{25bbe04ba8bf4f8fa0535e91bd31adce,
title = "Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes",
abstract = "More than 100,000 community wells have been installed in the 150–300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 µg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35–240 m depth range was sampled for tritium (3H), oxygen and hydrogen isotopes of water (18O/16O and 2H/1H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14C/12C and 13C/12C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon (14C) ages in DIC range from modern to 10 kyr. In the 90–240 m depth range, however, only five wells shallower than 150 m contain detectable 3H (<0.3 TU) and 14C ages of DIC cluster around 10 kyr. The radiogenic helium (4He) content in groundwater increases linearly across the entire range of 14C ages at a rate of 2.5 × 10−12 ccSTP 4He g−1 yr−1. Within the samples from depths >90 m, systematic relationships between 18O/16O, 2H/1H, 13C/12C, and 14C/12C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer.",
keywords = "arsenic, Bangladesh, groundwater dating, noble gas temperatures, radiocarbon, tritium",
author = "I. Mihajlov and M. Stute and Peter Schlosser and Mailloux, {B. J.} and Y. Zheng and I. Choudhury and Ahmed, {K. M.} and {van Geen}, A.",
year = "2016",
month = "5",
day = "1",
doi = "10.1002/2015WR018224",
language = "English (US)",
volume = "52",
pages = "3324--3349",
journal = "Water Resources Research",
issn = "0043-1397",
publisher = "American Geophysical Union",
number = "5",

}

TY - JOUR

T1 - Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes

AU - Mihajlov, I.

AU - Stute, M.

AU - Schlosser, Peter

AU - Mailloux, B. J.

AU - Zheng, Y.

AU - Choudhury, I.

AU - Ahmed, K. M.

AU - van Geen, A.

PY - 2016/5/1

Y1 - 2016/5/1

N2 - More than 100,000 community wells have been installed in the 150–300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 µg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35–240 m depth range was sampled for tritium (3H), oxygen and hydrogen isotopes of water (18O/16O and 2H/1H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14C/12C and 13C/12C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon (14C) ages in DIC range from modern to 10 kyr. In the 90–240 m depth range, however, only five wells shallower than 150 m contain detectable 3H (<0.3 TU) and 14C ages of DIC cluster around 10 kyr. The radiogenic helium (4He) content in groundwater increases linearly across the entire range of 14C ages at a rate of 2.5 × 10−12 ccSTP 4He g−1 yr−1. Within the samples from depths >90 m, systematic relationships between 18O/16O, 2H/1H, 13C/12C, and 14C/12C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer.

AB - More than 100,000 community wells have been installed in the 150–300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 µg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35–240 m depth range was sampled for tritium (3H), oxygen and hydrogen isotopes of water (18O/16O and 2H/1H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14C/12C and 13C/12C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon (14C) ages in DIC range from modern to 10 kyr. In the 90–240 m depth range, however, only five wells shallower than 150 m contain detectable 3H (<0.3 TU) and 14C ages of DIC cluster around 10 kyr. The radiogenic helium (4He) content in groundwater increases linearly across the entire range of 14C ages at a rate of 2.5 × 10−12 ccSTP 4He g−1 yr−1. Within the samples from depths >90 m, systematic relationships between 18O/16O, 2H/1H, 13C/12C, and 14C/12C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer.

KW - arsenic

KW - Bangladesh

KW - groundwater dating

KW - noble gas temperatures

KW - radiocarbon

KW - tritium

UR - http://www.scopus.com/inward/record.url?scp=84992303970&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84992303970&partnerID=8YFLogxK

U2 - 10.1002/2015WR018224

DO - 10.1002/2015WR018224

M3 - Article

AN - SCOPUS:84992303970

VL - 52

SP - 3324

EP - 3349

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

IS - 5

ER -