title: Geochemical associations and availability of cadmium (Cd) in a paddy field system, northwestern Thailand.
abstract: The Mae Tao watershed, northwest Thailand, has become contaminated with cadmium (Cd) as a result of zinc ore extraction (Padaeng deposit) in the nearby Thanon-Thongchai mountains. Consumption of contaminated rice has led to documented human health impacts. The aim of this study was to elucidate transfer pathways from creek and canal waters to the paddy field soils near Baan Mae Tao Mai village and to determine the relationship between Cd speciation in the soil and uptake by rice plants. Transfer mainly occurred in association with particulate matter during flooding and channel dredging and, in contrast with many other studies, most of the soil Cd was associated with exchangeable and carbonate-bound fractions. Moreover, there was a linear relationship between soil total Cd and rice grain Cd (R(2) = 0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R(2) = 0.898 and 0.862, respectively).
authors: School of GeoSciences, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JN, UK.
authors: Peerapat
authors: P
authors: Kosolsaksakul
authors: School of GeoSciences, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JN, UK.
authors: John G
authors: JG
authors: Farmer
authors: School of Physical and Geographical Sciences, Keele University, Keele ST5 5BG, UK.
authors: Ian W
authors: IW
authors: Oliver
authors: School of GeoSciences, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JN, UK. Electronic address: Margaret.Graham@ed.ac.uk.
authors: Margaret C
authors: MC
authors: Graham
mesh_terms: D000383:Agriculture; D002104:Cadmium / Q000032:analysis*; D008906:Mining; D012275:Oryza / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D013785:Thailand; D014874:Water Pollutants, Chemical / Q000032:analysis*; D015032:Zinc
chemical_list: D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D002104:Cadmium; D015032:Zinc
keywords: Cadmium; Rice; Sediment; Sequential extraction; Soil characterisation