title: [Transformation and mobility of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages of rice].
abstract: Speciation and bioavailability of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages (tillering stage, jointing stage, booting stage, filling stage and maturing stage) of rice (Oryza sativa L.) were studied using toxicity characteristic leaching procedure (TCLP) and arsenic speciation analysis. Pot experiments were conducted and the soil samples were taken from a certain paddy soil in Hunan Province contaminated by mining industry. The results showed that: (1) With the extension of rice growth period, pH values and TCLP extractable arsenic levels in the rhizosphere and non-rhizosphere soils increased gradually. Soil pH and TCLP extractable arsenic levels in non-rhizosphere soils were higher than those in the rhizosphere soils at the same growth stage. (2) At the different growth stages of rice, contents of exchangeable arsenic (AE-As) in rhizosphere and non-rhizosphere soils were lower than those before the rice planting, and increased gradually with the extension of the rice growing period. Contents of Al-bound arsenic (Al-As), Fe-bound arsenic (Fe-As) and Ca-bound arsenic (Ca-As) increased gradually after rice planting, but not significantly. Residual arsenic (O-As) and total arsenic (T-As) decreased gradually after rice planting, by 37.30% and 14.69% in the rhizosphere soils and by 31.38% and 8.67% in the non-rhizosphere soils, respectively. (3) At the different growth stages of rice, contents of various forms of arsenic in the soils were in the following order: residual arsenic (O-As) > Fe-bound arsenic ( Fe-As) > Al-bound arsenic (Al-As) > Ca-bound arsenic (Ca-As) > exchangeable arsenic (AE-As). In the pH range of 5.0- 5.8, significant positive linear correlations were found between most forms of arsenic or TCLP extractable arsenic levels and pH values, while the Ca-bound arsenic was poorly correlated with pH values in the rhizosphere soils.
authors.forename: Wen-Tao
authors.initials: WT
authors.lastname: Yang
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Wang
authors.forename: Hang
authors.initials: H
authors.lastname: Zhou
authors.forename: Kai-Xin
authors.initials: KX
authors.lastname: Yi
authors.forename: Min
authors.initials: M
authors.lastname: Zeng
authors.forename: Pei-Qin
authors.initials: PQ
authors.lastname: Peng
authors.forename: Bo-Han
authors.initials: BH
authors.lastname: Liao
mesh_terms: D001151:Arsenic / Q000032:analysis*; D012275:Oryza; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D001151:Arsenic