不同淋溶方式下石英砂柱中铁锰的运移淀积特征

以石英砂为装柱材料，用不同浓度的铁锰单一或混合溶液淋溶石英砂柱40次，研究淋溶液的pH（pH5，pH3．5），铁锰物质的量比（1：1，2：1，4：1）和淋溶方式（铁锰同时淋溶或交替淋溶）等因素对石英砂柱中铁锰淀积和运移的影响。结果表明：i）不同淋溶方式的处理间铁锰形态分布存在显著差异。随淋溶次数的增加，铁锰同时淋溶的砂柱内，各形态的铁锰淀积量逐渐增加，而铁锰交替淋溶砂柱内的铁锰含量随淋溶阶段而变化；2）相同淋溶方式，不同铁锰物质的量比处理的砂柱间铁锰淀积量差异显著，淋溶液锰浓度高的处理其游离锰、非晶锰的淀积量较大；3）相同铁锰物质的量比，铁锰同时淋溶处理的游离铁锰和非晶质铁的淀积量高于相应交替淋溶的，而非晶质锰的反之；4）pH3．5淋溶处理的砂柱中，铁锰淀积量总体高于pH5的，以下层（25cm）的含量最高，铁锰具有向下运移的规律，但在pH5淋溶处理的砂柱中该现象不明显；5）石英砂表面淀积的游离和非晶质铁锰随着淋溶的进行总体呈现增加的趋势，前期淀积的游离铁锰对后阶段游离铁锰的形成有促进作用，游离铁与非晶质铁的淀积量呈正相关。

Characteristics of migration and deposition of iron and manganese in quartz sand columns under different leaching conditions

The characteristics of migration and deposition of iron and manganese in the columns were studied, and the factors af- fecting the leaching were investigated. The quartz sand columns were leached 40 times with single or mixed solution of iron and manganese at pH 5 or pH 3.5, and mass ratios of Fe/Mn were set as 1 ： 1, 2 ： 1, 4 ： 1. Different leaching ways （simultaneously and alternately） were adopted. The results as as follows. 1） Different leaching ways resulted in significant difference in the distri- bution of iron and manganese. In the quartz sand columns leached with mixed iron and manganese solution, the deposition amount of different forms of iron-manganese oxides increased as the leaching times increased. However, the amount of iron-manganese oxides in the quartz sand columns which were leached with iron or manganese solution alternately changed periodically. 2） In the same leaching way, the illuviation of iron-manganese oxides had significant differences at different mass ratios of Fe/Mn. High manganese treatment resulted in high amounts of free and amorphous forms of manganese oxides. 3） The amounts of free iron- manganese oxides and amorphous iron oxides were higher in simultaneously leached columns than those in alternate conditions at the same mass ratio of Fe/Mn. 4） The amount of iron-manganese iltuviation was higher in the quartz sand columns leached with pH 3.5 solutions than that by pH 5 solutions, and the peak amount appeared in the lower layers （25 cm） of columns. Therefore, there was a tendency of iron-manganese migrating downward in the quartz sand columns leached with pH 3.5 solutions. Howev- er, this phenomenon was not obvious in pH 5 treatments. 5） With the leaching times increasing, the amounts of free and amor- phous manganese oxides illuviated on the quartz sand had an overall increasing trend. The free iron-manganese oxides formed in the early stage of leaching promoted the illuviation of the oxides in the later period, and the depositions of free and amorphous iron oxides were positively correlated.