红壤中铝的形态

FORMS OF ALUMINUM IN RED SOILS

以改进的连续分级提取方法，用1mol／LKCl，0．2mol／LHCl，0．1mol／LNa4P2O7（pH8．5），DCB溶液，0．33mol／L柠檬酸钠（pH7．3）和0．5mol／LNaOH为提取剂，把红壤中可提取的非晶态铝区分为交换态铝（ExAl），吸附态无机羟基铝（HyAl），有机配合态铝（OrAl），氧化铁结合态铝（DCBAl），层间铝（InAl）和非晶态铝硅酸盐（NcAl）。每一种铝形态在其结构组成和性质上都有自己固有的特征，并与红壤相应的性质和生态特征密切相关。在同一个土壤中，其数量上有NcAl＞InAl＞DCBAl＞OrAl＞HyAl＞ExAl的趋势。除ExAl外，其余五种铝形态均为玄武岩发育的红壤多于花岗岩发育的红壤。土壤中铝大部分以层状铝硅酸盐矿物存在。并以选择性溶解方法单独提取作比较。

Extractable noncrystalline aluminum in red soils could be fractionated into exchangeable Al (ExAl), adsorbed inorganic hydroxyr-Al (HyAl), organic complexed Al(OrAl), Fe oxide bound Al (DCBAl), interiayered Al (InAl) and noncrystalline aluminosilicate (NcAl), by the 1 mol / L KCl, 0.2mol / L HCl, 0.1 mol / L Na4P2O7(pH8.5), DCB solution, sodium citrate (0.33 mol / L, pH7.3) and 0.5 mol / L NaOH sequential extraction. All Al forms were characterized by the intrinsic feature in their composition and properties and closely related to the corresponding properties and ecological characteristics of red soils. In the same soil sample the amounts of various Al forms were of the order NcAl > InAl > DCBAI > OrAl > HyAl > ExAl. With the exception of ExAl content the contents of other five forms of aluminum in the red soils derived from basalt were higher than those from grate. In soils most of the aluminum existed in layer aluminosilicate minerals. Individual extraction of the Al forms in soils was compared with the sequential extraction method.