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Accumulation of iron and arsenic in the Chandina alluvium of the lower delta plain, Southeastern Bangladesh

Environmental Geochemistry and Health

By:
, , , , and
DOI: 10.1007/s10653-008-9226-1

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Abstract

Accumulations of iron, manganese, and arsenic occur in the Chandina alluvium of southeastern Bangladesh within 2.5 m of the ground surface. These distinctive orange-brown horizons are subhorizontal and consistently occur within 1 m of the contact of the aerated (yellow-brown) and water-saturated (gray) sediment. Ferric oxyhydroxide precipitates that define the horizons form by oxidation of reduced iron in pore waters near the top of the saturated zone when exposed to air in the unsaturated sediment. Hydrous Fe-oxide has a high specific surface area and thus a high adsorption capacity that absorbs the bulk of arsenic also present in the reduced pore water, resulting in accumulations containing as much as 280 ppm arsenic. The steep redox gradient that characterizes the transition of saturated and unsaturated sediment also favors accumulation of manganese oxides in the oxidized sediment. Anomalous concentrations of phosphate and molybdenum also detected in the ferric oxyhydroxide-enriched sediment are attributed to sorption processes. ?? Springer Science+Business Media B.V. 2008.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Accumulation of iron and arsenic in the Chandina alluvium of the lower delta plain, Southeastern Bangladesh
Series title:
Environmental Geochemistry and Health
DOI:
10.1007/s10653-008-9226-1
Volume
31
Issue:
SUPPL. 1
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Geochemistry and Health
First page:
69
Last page:
84