Source and release mechanism of arsenic in aquifers of the Mekong Delta, Vietnam

In order to elucidate the arsenic source and its release mechanism into groundwater in the Mekong Delta, Vietnam, groundwater samples were collected from wells at different depths (20 to 440 m) and core samples (from 20 to 265 m depth) were analyzed. Based on the analytical results for groundwater a...

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Bibliographic Details
Published in:Journal of contaminant hydrology 2009-01, Vol.103 (1), p.58-69
Main Authors: Nguyen, Kim Phuong, Itoi, Ryuichi
Format: Article
Language:English
Subjects:
acid sulfate soils
aquifers
Arsenic
Arsenic - analysis
Arsenic - chemistry
Earth sciences
Earth, ocean, space
Exact sciences and technology
Ferric Compounds - chemistry
geochemistry
Geography
groundwater
hydrochemistry
Hydrogeology
Hydrology. Hydrogeology
hydrous ferroxide oxide
Iron - chemistry
Iron hydroxides
iron oxides
Mekong Delta
pyrites
Redox condition
Soil
sulfides
Sulfides - chemistry
Vietnam
Water - chemistry
Water Movements
Water Pollutants, Chemical - analysis
Water Pollutants, Chemical - chemistry
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Summary:In order to elucidate the arsenic source and its release mechanism into groundwater in the Mekong Delta, Vietnam, groundwater samples were collected from wells at different depths (20 to 440 m) and core samples (from 20 to 265 m depth) were analyzed. Based on the analytical results for groundwater and core samples, the As source in groundwater is considered to be pyrite (FeS 2) in acid sulfate soil (ASS) under oxidizing conditions and hydrous ferric oxide (Fe(OH) 3) under reducing conditions. Geochemical modeling demonstrated that As(III) is the dominant species and the presence of As-bearing sulfides, Fe-bearing sulfides and oxides phases may locally act as potential sinks for As. From variation between Fe and As concentrations in groundwater samples, the release mechanism of As is: dissolution of Fe(OH) 3 containing As under reducing conditions and oxidative decomposition of FeS 2 containing As under oxidizing conditions.
ISSN:0169-7722
1873-6009
DOI:10.1016/j.jconhyd.2008.09.005