不同施肥处理土壤胡敏酸及其级分与Fe2+络合特征Ⅱ.胡敏酸级分与Fe2+络合特征

采用酒精沉淀法对不同施肥处理胡敏酸进行分级 ,在研究胡敏酸级分组成变异以及各级分性质变化的基础上 ,研究了胡敏酸各级分与Fe2+的络合特征。结果表明 ,胡敏酸各级分随级分数的增大芳构化度逐渐降低 ,分子结构趋于简单。在所分离的 7个级分中 ,均以级分 3与Fe2+的络合能力最强。从级分 1到级分 3络合能力逐渐增强 ,级分 3到级分 7络合能力逐渐降低。胡敏酸A型级分的络合能力一般大于P型。但若A型级分芳构化度过高 ,也存在A型级分小于P型现象。Rp型级分的络合能力明显比A型、P型级分小。不同施肥处理胡敏酸原样与Fe2+络合能力差异与其级分组成变异以及各级分的络合能力有密切关系

Complexation characteristics of humic acids with Fe2+ and their fraction s from soil with different fertilization

Humic acids from different fertilization were fraction ated byalcohol precipitation technique, complexation characteristic of the fractions with Fe 2+ were studied on the basis of studying the properties of the fractions. The resu l ts showed that the condensation degree of the fractions decreased and the struct ure became simpler with the fractional number increase. Complex ability of the third fraction was the highest among all the 7 fractions, which increased from f raction 1 to fraction 3, and decreased from fraction 3 to fraction 7. This reve a led that it was not benefit for complex if the molecular structure of the fracti on of humic acid was too simple or too complicated, existing an optimum molecula r state among the fractions for complex. The complex ability of A type fraction of humic acid was higher than that of P type, if the A type fraction was too com plicated, the opposite was true. The complex ability of Rp type fraction of hu m ic acid was lower than that of A or P type significantly. The difference on com p lex ability of humic acids with different fertilization was related to their fra ctional composition variation and their fraction's complex ability.