Redox reaction of iodine in paddy soil investigated by field observation and the I K-Edge XANES fingerprinting method.
In order to elucidate the cause for the leaching of iodine in a flooded paddy field, we investigated the transformation of an iodine species affected by the water management of the paddy field. The increased concentration of iodide (I(-)) in soil solution of a flooded paddy field suggested that I(-) was leached from the soil under anaerobic conditions. The post-edge feature of X-ray absorption near-edge structure (XANES) for iodate (IO(3)(-)) spiked to soil totally disappeared after anaerobic incubation of the soils, and I(-) was dissolved in the solution. On the other hand, I(-) in contact with the soil was not likely to be oxidized to IO(3)(-) under aerobic incubation. Iodine was leached out in soil solution as I(-) under anaerobic conditions, whereas part of the iodine species was retained by soil as I(2) or organoiodine both under anaerobic and aerobic conditions.
Yamaguchi
N
N
National Institute for Agro-Environmental Sciences, 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan. nyamag@affrc.go.jp
Nakano
M
M
Tanida
H
H
Fujiwara
H
H
Kihou
N
N
D007455:Iodine / Q000737:chemistry*; D010084:Oxidation-Reduction; D012987:Soil / Q000032:analysis*; D013057:Spectrum Analysis / Q000379:methods*; D014965:X-Rays
D012987:Soil; D007455:Iodine