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Groundwater chemistry and arsenic mobilization in the Holocene flood plains in south-central Bangladesh
- Source :
- Environmental Geochemistry and Health. 31:23-43
- Publication Year :
- 2009
- Publisher :
- Springer Science and Business Media LLC, 2009.
-
Abstract
- A comparative study of arsenic enrichment in the Bengal Delta (BD) was carried out in three alluvial aquifers in south-central Bangladesh. Investigated sites included Sonargaon in Narayanganj, Chandina in Comilla and Sirajdikhan in Munshiganj districts. At all sites samples from different depths were collected, and water chemistry and redox status vs. depth trends were determined. The concentrations of DOC and HCO3 − were highest at Sirajdikhan site, while at the Sonargaon and Chandina sites the concentrations were lower. On the contrary, the NH4 + concentration was high at the Chandina site as compared to the other sites. There was a good match between dissolved As and Fe at the Sirajdikhan and Sonargaon sites, but not at the Chandina site. The dissolved aqueous concentration of Mn was low at the Chandina site, which suggested that the Mn(IV) redox buffering step was missing. Speciation modeling indicated a possibility of siderite precipitation at all sites, but precipitation of rhodochrosite only at the Sonargaon and Sirajdikhan sites. At the Sirajdikhan site, the log $$ {\text{P}}_{{{\text{CO}}_{ 2} }} $$ values were very high (−1.37), which revealed the production of CO2 in redox processes. Principal component analysis (PCA) indicated an impact of sea water and redox status of different samples. These results suggest that the dissolved As is de-coupled from dissolved Mn because when released, As is re-adsorbed onto the Fe(III) minerals in solid phase, as well as from dissolved Fe when precipitation of Fe(II) minerals controls the aqueous concentrations of Fe. In addition, several other concurrent redox processes may exert kinetic constraints depending on refractory characteristics of Fe(III) minerals.
- Subjects :
- Geologic Sediments
Environmental Engineering
Rhodochrosite
Iron
chemistry.chemical_element
Manganese
Redox
Arsenic
Siderite
chemistry.chemical_compound
Geochemistry and Petrology
Groundwater pollution
groundwater
precipitation of secondary minerals
Chemical Precipitation
Environmental Chemistry
General Environmental Science
Water Science and Technology
Bangladesh
Principal Component Analysis
Aqueous solution
arsenic
General Medicine
Carbon
Quaternary Ammonium Compounds
speciation
chemistry
redox buffering
Environmental chemistry
Seawater
Oxidation-Reduction
Water Pollutants, Chemical
Environmental Monitoring
Subjects
Details
- ISSN :
- 15732983 and 02694042
- Volume :
- 31
- Database :
- OpenAIRE
- Journal :
- Environmental Geochemistry and Health
- Accession number :
- edsair.doi.dedup.....48a47fd4b9ba48ebadbd9727d7214c51