Geochemical associations and availability of cadmium (Cd) in a paddy field system, northwestern Thailand

• Published in: Environmental pollution (1987) 2014-04, Vol.187, p.153-161
• Main Authors: Kosolsaksakul, Peerapat, Farmer, John G., Oliver, Ian W., Graham, Margaret C.
• Format: Article
• Language: English
• Subjects: Agriculture; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Cadmium; Cadmium - analysis; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Grains; Mining; Mountains; Non agrochemicals pollutants; Northwest; Oryza - chemistry; Phytopathology. Animal pests. Plant and forest protection; Pollution; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; Pollution, environment geology; Rice; Sediment; Sequential extraction; Soil - chemistry; Soil and sediments pollution; Soil characterisation; Soil Pollutants - analysis; Soils; Thailand; Water Pollutants, Chemical - analysis; Zinc
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2014.01.006

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 (R2 = 0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R2 = 0.898 and 0.862, respectively). •Cd associated with clays and carbonates in canal sediments and paddy field soils.•SEM–EDX and sequential extraction results for sediments and soils agree well.•Linear relationship between Cd in soil and in rice grains from the same fields.•Uptake of Cd by rice plants strongly linked to soil Cd speciation. Cd was mainly associated with carbonates and clays. The strong relationship between soil and rice grain Cd was primarily due to the prevalence of easily extractable-Cd within the soil.