Selenium speciation in seleniferous agricultural soils under different cropping systems using sequential extraction and X-ray absorption spectroscopy.
Selenium (Se) speciation in soil is critically important for understanding the solubility, mobility, bioavailability, and toxicity of Se in the environment. In this study, Se fractionation and chemical speciation in agricultural soils from seleniferous areas were investigated using the elaborate sequential extraction and X-ray absorption near-edge structure (XANES) spectroscopy. The speciation results quantified by XANES technique generally agreed with those obtained by sequential extraction, and the combination of both approaches can reliably characterize Se speciation in soils. Results showed that dominant organic Se (56-81% of the total Se) and lesser Se(IV) (19-44%) were observed in seleniferous agricultural soils. A significant decrease in the proportion of organic Se to the total Se was found in different types of soil, i.e., paddy soil (81%) > uncultivated soil (69-73%) > upland soil (56-63%), while that of Se(IV) presented an inverse tendency. This suggests that Se speciation in agricultural soils can be significantly influenced by different cropping systems. Organic Se in seleniferous agricultural soils was probably derived from plant litter, which provides a significant insight for phytoremediation in Se-laden ecosystems and biofortification in Se-deficient areas. Furthermore, elevated organic Se in soils could result in higher Se accumulation in crops and further potential chronic Se toxicity to local residents in seleniferous areas.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: qinhaibo@vip.gyig.ac.cn.
Hai-Bo
HB
Qin
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China. Electronic address: jmzhu@cugb.edu.cn.
Jian-Ming
JM
Zhu
Environmental Sciences Program and Department of Biological Sciences, Southern Illinois University, Edwardsville, IL 62026-1099, USA.
Zhi-Qing
ZQ
Lin
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Wen-Po
WP
Xu
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China.
De-Can
DC
Tan
Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Li-Rong
LR
Zheng
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
Yoshio
Y
Takahashi
D000383:Agriculture / Q000379:methods*; D001673:Biodegradation, Environmental; D001682:Biological Availability; D005591:Chemical Fractionation; D018556:Crops, Agricultural; D012643:Selenium / Q000032:analysis* / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy; D014965:X-Rays
D012987:Soil; D012989:Soil Pollutants; D012643:Selenium
Fractionation; Seleniferous agricultural soils; Selenium speciation; Sequential extraction; X-ray absorption near-edge structure (XANES)