Effect of coordination structure of aluminum on its activation from minerals and Oxisols during their acidification  

作　　者：Kewei LI Yangxiaoxiao SHI Jackson Nkoh NKOH Jun JIANG Renkou XU 

机构地区：[1]State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Pedosphere》2024年第5期916-928,共13页土壤圈（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.U19A2046)。

摘　　要：The types and contents of phyllosilicate minerals in soils play an important role in soil acidification,as soil acid buffering capacity varies with the composition of the phyllosilicate minerals.In addition to aluminum-oxygen(Al-O)octahedrons,a certain number of Al-O tetrahedrons exist in phyllosilicate minerals due to the isomorphic substitution of silicon ion(Si4+)by aluminum ion(Al3+)in Si-O tetrahedrons of minerals.However,the effect of the two coordination structures of Al on the release of Al during mineral acidification has not yet been investigated.Therefore,the differences in Al activation in phyllosilicate minerals and soils with different Al coordination structures were investigated through constant-p H experiments and27Al magic-angle spinning nuclear magnetic resonance(MAS-NMR)measurements.The results of27Al MAS-NMR spectra showed that kaolinite contained Al-O octahedrons,phlogopite and illite contained Al-O tetrahedrons,and vermiculite composite contained both octahedral and tetrahedral Al.At p H<5.1,the content of Al released from minerals during simulated acidification followed the order:illite>vermiculite composite>phlogopite>kaolinite,which was consistent with the orders of cation exchange capacity and content of tetrahedral Al of the minerals.According to the rate constants,the Al release rates were in the order of phlogopite>illite>vermiculite composite>kaolinite at p H 4.8.Except for phlogopite,the Al release rates in these minerals increased with decreasing suspension p H.Therefore,the Al release contents and rates were greater in phlogopite,illite,and vermiculite composite containing Al-O tetrahedrons than in kaolinite containing only Al-O octahedrons.Two Oxisols derived from basalt with different ages were selected for similar studies.The27Al MAS-NMR spectra of the Oxisols showed that the 0.01-million-year(Ma)Oxisol contained both octahedral and tetrahedral Al,while the 1.33-Ma Oxisol contained only Al-O octahedrons.The contents of both exchangeable and soluble Al released from the 0.01-Ma

关 键 词：Al-O octahedrons Al-O tetrahedrons aluminum release exchangeable Al phyllosilicate minerals soil acidification 

分 类 号：S153[农业科学—土壤学]