Geochemical insights of arsenic mobilization into the aquifers of Punjab, Pakistan.

Autor: Sadiq M; Department of Biosciences, COMSATS University, Park Road, 44000 Islamabad, Pakistan; Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland., Eqani SAMAS; Department of Biosciences, COMSATS University, Park Road, 44000 Islamabad, Pakistan. Electronic address: alishah@comsats.edu.pk., Podgorski J; Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland., Ilyas S; Department of Environmental Sciences, Forman Christian College (A Chartered University), 54600 Lahore, Pakistan., Abbas SS; Department of Biosciences, COMSATS University, Park Road, 44000 Islamabad, Pakistan., Shafqat MN; Department of Biosciences, COMSATS University, Park Road, 44000 Islamabad, Pakistan., Nawaz I; Department of Biosciences, COMSATS University, Park Road, 44000 Islamabad, Pakistan., Berg M; Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Jul 20; Vol. 935, pp. 173452. Date of Electronic Publication: 2024 May 21.
DOI: 10.1016/j.scitotenv.2024.173452
Abstrakt: It is well known that groundwater arsenic (As) contamination affects million(s) of people throughout the Indus flood plain, Pakistan. In this study, groundwater (n = 96) and drilled borehole samples (n = 87 sediments of 12 boreholes) were collected to investigate geochemical proxy-indicators for As release into groundwater across floodplains of the Indus Basin. The mean dissolved (μg/L) and sedimentary As concentrations (mg/kg) showed significant association in all studied areas viz.; lower reaches of Indus flood plain area (71 and 12.7), upper flood plain areas (33.7 and 7.2), and Thal desert areas (5.3 and 4.7) and are indicative of Basin-scale geogenic As contamination. As contamination in aquifer sediments is dependent on various geochemical factors including particle size (3-4-fold higher As levels in fine clay particles than in fine-coarse sand), sediment types (3-fold higher As in Holocene sediments of floodplain areas vs Pleistocene/Quaternary sediments in the Thal desert) with varying proportion of Al-Fe-Mn oxides/hydroxides. The total organic carbon (TOC) of cored aquifer sediments yielded low TOC content (mean = 0.13 %), which indicates that organic carbon is not a major driver (with a few exceptions) of As mobilization in the Indus Basin. Alkaline pH, high dissolved sulfate and other water quality parameters indicate pH-induced As leaching and the dominance of oxidizing conditions in the aquifers of upper flood plain areas of Punjab, Pakistan while at the lower reaches of the Indus flood plain and alluvial pockets along the rivers with elevated flood-driven dissolved organic carbon (exhibiting high dissolved Mn and Fe and a wide range of redox conditions). Furthermore, we also identified that paired dissolved AsMn values (instead of AsFe) may serve as a geochemical marker of a range of redox conditions throughout Indus flood plains.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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