中文摘要：

通过水稻盆栽试验，用零价铁固定湖南郴州污染稻田土壤中砷，分析水稻种植前和收获后水稻土中各形态砷、浸出砷及各形态铁含量的变化，研究零价铁固定稻田土壤砷效果的持久性，并从形态作用方面初步探讨固定机理。结果表明，零价铁显著降低水稻种植前和收获后土壤易溶型砷（WE—As）含量。在最大添加量8．00g／kg时，零价铁使种植前和收获后土壤中WE—As分别比对照降低77．5％和74．7％。零价铁亦显著降低种植前土壤砷浸出量（p〈0．05），但收获后土壤砷浸出量的降低未达显著水平。尽管收获水稻后砷浸出量的降低效果有所减弱，但总体上在一个水稻生育期内，零价铁固定土壤砷的效果有较好的持久性。从形态方面解释，零价铁固定土壤砷的机理主要是零价铁在土壤中转化为无定形铁（AO—Fe）、碳酸盐结合态铁（C～Fe）、氧化锰结合态铁（Mn—Fe）等能强吸附砷或与砷共沉淀的形态铁，与土壤中WE—As、铝型砷（A1-As）、铁型砷（Fe—As）反应，使其主要向稳定性强的残渣态砷（Rs—As）转化。

英文摘要：

A rice pot experiment was conducted to study the persistence of immobilization effects on paddy soil arsenic （As） using zero-valent iron and the As immobilization mechanisms. Different amounts of zero- valent iron were added into As contaminated paddy soil which was sampled in Chenzhou of Hunan province. Before rice planting and after harvesting, the contents of As fractions, leachable As and iron （Fe） fractions in immobilized soils were determined. The results showed that zero-valent iron significantly decreased the contents of soil WE-As before rice planting and after harvesting. When the addition amount of zero-valent i- ron reached the maximum level （8.00 g/kg）, the soil WE-As decreased by 77.5% before rice planting and 74.7% after rice harvesting, compared with the control. Moreover, leachable As in soil decreased signifi- cantly before rice planting （p〈0.05） but unremarkably after rice harvesting. Although, the effect of reduc- ing soil leachable As was wakened after rice harvesting, zero-valent iron could immobilize paddy soil As per- sistently in a rice growth period. Explaining the immobilization mechanism from fraction aspect, the zero- valent iron was first transformed into those iron fractions which could adsorb or/and copreeipitate with soil As, such as amorphous iron （AO-Fe）, carbonate iron （C-Fe） and manganese oxide iron （Mn-Fe）. Then these irons reacted with WE-As, Al-bound As （AI-As）, Fe-bound As （Fe-As）, and turned them into residu- al As （RS-As） with better stability.