A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia |
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Authors: | Email author" target="_blank">Gordon?StangerEmail author |
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Institution: | (1) UNDP, Box 551, Sanaá, Yemen |
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Abstract: | An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common
origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further
concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain.
Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and
Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily
redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and
authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above
palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern
Asia. |
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Keywords: | arsenic Chindwin Cimmeride Ganges GBM groundwater Irrawady Mekong Meso-Tethys Naga Palaeo-Tethys Qamdo-Simao Red River Siwalik Salween |
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