黄土中铁的形态分布及其组合特征研究

通过对采自陕西各地马兰黄土上部样品中８种形态铁和全铁含量以及碳酸盐、有机质、ｐＨ等有关因素分析，发现黄土中不同形态铁的含量差异很大。其中铝硅酸盐矿物铁、晶形铁和无定形铁是黄土中铁的主要存在形态，三者的含量合计可占全铁量的９９．８％以上，其余代换态铁、松结有机铁、碳酸盐结合铁、氧化锰结合铁和紧结有机铁５者的含量合计不到全铁量的０．２％。黄土各形态铁的含量变化具有同步消长特征，而全铁含量是各形态铁含量的主要制约因素，在区域上黄土碳酸盐和全铁含量的极显著正相关关系主要与颗粒和矿物成分的变化有关，黄土有机质的积累过程不但有益于有机结合铁形成，同时亦有益于其他各形态铁以及全铁富集，而黄土的碱化作用过程不利于铁的形态分异。

A STUDY ON THE DISTRIBUTION OF IRON SPECIES AND THEIR COMPOSITE ChARACTERISTICS IN LOESS

Eight species and total contents of iron in Malan loess were analyzed by sampling from different occurrences in Shanxi Province,China,and also carbonate,organic matter and pH were determined.The results show that silicate,crystalline and amorphous states are major species,which make up 99 8% of the total contents of iron in the loess,whereas the other five species (substitutable,carbonate,manganese oxide,loosely bound and tightly bound organic states)are only 0 2%.The contents of all iron species varied synchronously and were mainly affected by the iron total contents in the loess.The carbonate species of iron was remarkably related to total contents in region distribution that was owing to mineral constituents and grain sizes in loess.The organic matter accumulation promoted the formation of both organic bound species of iron as well as enrichments of other species and total contents of iron in the loess.The alkalization of the loess,however,was not of benefit to species differentiation of iron.