铁锰氧化物在污染土壤修复中的作用

矿物学在环境科学中的应用将是21世纪矿物学研究的一个主要方面。土壤污染作为一个制约人类社会可持续发展的基本问题正受到日益广泛的关注，污染土壤的修复已成为环境科学研究的一个重点。污染土壤的修复技术主要有物理、化学、生物等方法，但是，它们都不同程度地存在着缺陷。众所周知，铁和锰是自然界中少数但常见的变价元素。含有变价元素和带有表面电荷的铁锰氧化物具有良好的表面活性，不仅对有毒有害的无机污染物具有良好的净化功能，而且对土壤中有机污染物具有氧化降解作用。利用这些矿物来修复污染土壤，具有成本低、无二次污染等优点，体现出天然净化作用的特色，展现出广阔的环境矿物学应用前景。

THE ENVIRONMENTAL MINERALOGICAL SIGNIFICANCE OF IRON AND MANGANESE OXIDES IN REMEDIATION OF CONTAMINATED SOIL

The application of mineralogy in environmental sciences will be a major aspect of mineralogical studies in the 21st century. Soil contamination, as one of fundamental problems restricting the sustainable development of our society, is paid more and more attention. Remediation of contaminated soil has been one of the focuses of the research on environmental sciences. Various methods of remediation of contaminated soil, such as physics remediation, chemical remediation, bioremediation, have some problems to some degree existing in the research and the future task. It may be well known that iron and manganese are few but familiarly variable valence elements. Natural oxides of iron and manganese with surface charges and variable valence elements have favorable surface activities. They can not only decontaminate toxic inorganic pollutant, but also decompose and oxidize organic compound. Natural minerals, on behalf of magnetite, hematite, goethite, manganese dioxide and so on, are being one of significant research objects with relation to the methods using natural minerals to decontaminate pollutants at home and abroad. For example, the adsorption and desorption on the surfaces of iron and manganese oxides and their hydroxides happen to the elements such as Cu, Pb, Zn, Cr, Co, F, As, P and rare earth elements in red soil and other soils, mantle of waste and sediments on the earth's surface. It is of the opinion that the activities are one of important mechanism of the elements' activation, transposition and pollution in epigenetic circumstances. Iron and manganese oxides and hydroxides are ubiquitous in soils. They can interact with hydrogenant phenol compounds. It follows that their oxidative degradation abates poison to fauna and flora. And iron oxides are accelerators to the transformation and degradation of organic materials. Manganese ore has forceful adsorption ability to phenyl hydroxide, which adsorption process goes by second order equation of reaction kinetics, and its isothermal line of adsorption is the type of Langmuir. 
Many findings indicate that the oxides of iron and manganese are carriers of heavy metal ions retained by soils. Whereas, the objects of bygone studies are mostly artificially synthetic minerals, which surface properties have much discrepancy with those of natural minerals, so that it is difficult to apply the results of former studies to natural systems. By consequence, it is more useful to reinforce the study of natural iron and manganese oxides in soils.
With the population explosion and reduce of reclaimable wilderness in temperate zones, the global pivot of cultivation has transferred from temperate zones to tropic and subtropic zones. Forasmuch, it is very necessary to carry on the harness and rehabilitation of contaminated soil in these zones. In tropic and subtropic zones, the contents of iron oxides are comparatively high in yellow soil, laterite and red soil owing to the enrichment process of iron and aluminium. The contents of manganese oxides are lower than those of iron oxides, but the oxidizing abilities of manganese oxides are better than those of iron oxides. As a consequence of this, they are equally important to oxidative degradation of soil pollutants. Accordingly, it is rather impending to strengthen the studies on interaction effects between natural iron and manganese oxides and organic pollutants in soils in tropic and subtropic zones. It is propitious to find way to the studies on making use of natural minerals in soil to harness soil pollutants and enhance the harnessing ability of soil itself.
The methods of remedying contaminated soil by the agency of the environmental properties of the natural minerals are of characteristics of simple and feasible. Meanwhile, the artificial application of natural decontamination to pollution abatement of soil is conformable the order of nature. As the result that it has many advantages such as low cost, plummy effectiveness and no secondary pollution and so on. In this way, the studies of contaminated soil remediation can not only body forth the characteristics of natural decontamination, but also open out a vast range of application prospect for the research of environmental mineralogy.