• 论文 •

### 水铁矿的结构、组成及环境地球化学行为

1. 农业部亚热带农业资源与环境重点实验室； 华中农业大学 资源与环境学院， 湖北 武汉 430070
• 收稿日期:2010-05-20 修回日期:2010-10-08 出版日期:2011-03-15 发布日期:2011-04-15
• 作者简介:王小明（1985—），男，博士研究生，环境矿物学研究方向。E-ail：wangxm338@163.com
• 基金资助:

国家自然科学基金重点项目（40830527）；国家自然科学基金项目（40971142）；全国优秀博士学位论文作者资助项目（200767）；华中农业大学“国家大学生创新性试验计划”项目（091050404）

### The structure and composition of ferrihydrite and its environmental geochemical behaviors.

1. Key Laboratory of Subtropical Agriculture Resource and Environment, Ministry of Agriculture； College of Resources and Environment, Huazhong Agriculture University, Wuhan 430070, China
• Received:2010-05-20 Revised:2010-10-08 Online:2011-03-15 Published:2011-04-15

Abstract:

Ferrihydrite occurs widely in nature, such as in water body, soils, sediments and organisms. It has large surface area and high surface activity, controlling and influencing the morphology, migration and transformation of some contaminations and nutrient elements in the environment. It is also the important precursor form of many crystalloid iron (hydr)oxides. However, environmental geochemical behaviors of ferrihydrite and its implications for environments are not fully understood, which mainly presents in following aspects: (1)Ferrihydrite is always confused with amorphous iron (hydr)oxides or hydrate iron oxides and it is difficult to obtain experimental ferrihydrite samples in the environment and make quantitative analyses for them, whose contents are always underestimated. (2)Ferrihydrite is poorly crystallized, which makes the determination of its structure more difficult. The distribution, composition, structure and nature are not yet very clear. The XRD diffraction lines of ferrihydrite are wide, few and weak in intensity. Based on the number of diffraction lines, ferrihydrite can be classified into 2LFh with poorer crystallization and 6LFh with better crystallization. At present, generally accepted chemical formula of ferrihydrite is Fe5HO8·4H2O. However, lots of experiments have shown that H2O is not necessarily in its structure and it is easy to be replaced by external adsorbed matters. Some people think that ferrihydrite has a dualistic structure, i.e.with both octahedral coordination of its central Fe and tetrahedral coordination of surface Fe, which needs to be proved. Recently, structure study with use of PDF (Pair Distribution Function) shows that ideal ferrihydrite structure contents 20% tetrahedral coordination Fe and 80% octahedral coordination Fe and the chemical formula is Fe10O14(OH)2. However, quite a few researchers are doubtful of this new structure model. In this paper, the distribution, composition, structure and environmental geochemical behaviors of ferrihydrite are reviewed. The prospective research areas on ferrihydrite are also proposed.