Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia.
Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl(2), NH(4)NO(3), EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02M EDTA+0.5M NH(4)OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun, Jilin 130022, China.
Pengran
P
Guo
Xiaoyu
X
Jia
Taicheng
T
Duan
Jingwei
J
Xu
Hangting
H
Chen
D002681:China; D052918:Environmental Restoration and Remediation; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013910:Thorium / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D014908:Triticum / Q000254:growth & development / Q000378:metabolism*
D010710:Phosphates; D012990:Soil Pollutants, Radioactive; D013910:Thorium