Coupled redox cycling of arsenic and sulfur regulates thioarsenate enrichment in groundwater.
Sci Total Environ
; 943: 173776, 2024 Sep 15.
Article
in En
| MEDLINE
| ID: mdl-38862046
ABSTRACT
Higharsenic groundwater is influenced by a combination of processes reductive dissolution of iron minerals and formation of secondary minerals, metal complexation and redox reactions of organic matter (OM), and formation of more migratory thioarsenate, which together can lead to significant increases in arsenic concentration in groundwater. This study was conducted in a typical sulfur- and arsenic-rich groundwater site within the Datong Basin to explore the conditions of thioarsenate formation and its influence on arsenic enrichment in groundwater using HPLC-ICPMS, hydrogeochemical modeling, and fluorescence spectroscopy. The shallow aquifer exhibited a highly reducing environment, marked by elevated sulfide levels, low concentrations of Fe(II), and the highest proportion of thioarsenate. In the middle aquifer, an optimal ∑S/∑As led to the presence of significant quantities of thioarsenate. In contrast, the deep aquifer exhibited low sulfide and high Fe(II) concentration, with arsenic primarily originating from dissolved iron minerals. Redox fluctuations in the sediment driven by sulfuriron minerals generated reduced sulfur, thereby facilitating thioarsenate formation. OM played a crucial role as an electron donor for microbial activities, promoting iron and sulfate reduction processes and creating conditions conducive to thioarsenate formation in reduced and highsulfur environments. Understanding the process of thioarsenate formation and the influencing factors is of paramount importance for comprehending the migration and redistribution of arsenic in groundwater systems.
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01-internacional
Database:
MEDLINE
Language:
En
Journal:
Sci Total Environ
Year:
2024
Document type:
Article
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