The arsenic cycle in Late Quaternary fluvial sediments: Mineralogical considerations

Late Quaternary fluvial sediments have been identified as the immediate source of arsenic in groundwater in the delta region of the Ganges in India and Bangladesh as well as the Red River in Vietnam. Rock weathering in the catchment area is the obvious mechanism by which the sediments have acquired...

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Bibliographic Details
Published in:Current science (Bangalore) 2003-04, Vol.84 (8), p.1102-1104
Main Authors: Raymahashay, B. C., Khare, A. S.
Format: Article
Language:English
Subjects:
Arsenic
Delta soils
Groundwater
Kaolinite
Minerals
River deltas
Rocks
Sedimentary soils
Sediments
SPECIAL SECTION: LATE CENOZOIC FLUVIAL DEPOSITS
Weathering processes
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Summary:Late Quaternary fluvial sediments have been identified as the immediate source of arsenic in groundwater in the delta region of the Ganges in India and Bangladesh as well as the Red River in Vietnam. Rock weathering in the catchment area is the obvious mechanism by which the sediments have acquired the arsenic load. A hard rock terrain in central India offers examples of such weathering reactions. Mafic and felsic igneous bed rocks of this area contain arsenopyrite and arsenian pyrite. Residual soil proflies are lateritic with goethite and kaolinite as major constituents. Desorption experiments indicated that the soil minerals had quantitatively retained arsenic. Similar adsorption sites could have contributed to the transport and deposition of arsenic in deltaic sediments. The recent mobilization into groundwater is apparently controlled by a series of competitive redox reactions.
ISSN:0011-3891