应用穆斯堡尔谱和X射线法研究红壤性水稻土的氧化铁矿物

应用穆斯堡尔谱和X射线法分析研究红壤性水稻土的氧化铁矿物,研究结果表明,红壤性水稻土的氧化铁矿物组成、特性及其形成转化与起源土壤具有明显的差异。水稻土的成土条件不利于赤铁矿的形成。红壤的粘粒氧化铁矿物以赤铁矿和高铝替代(>20摩尔%)的针铁矿为主。经淹水种稻后,赤铁矿逐渐被转化为低铝替代的针铁矿或其它形态氧化铁。渗育型水稻土P层的赤铁矿含量比相应的母土低,其针铁矿铝替代量较其它水型的水稻土高。而潴育型水稻土W层和潜育型水稻土G层粘粒氧化铁矿物均以针铁矿为主,其铝同晶替代量低(<15摩尔%),且颗粒细小,结晶度较低。这些结果反映了水稻土的成土条件和发生特点,同时对水稻土发生分类具有重要的意义。

STUDIES ON IRON OXIDE MINERALOGY OF PADDY SOILS DERIVED FROM RED EARTH BY USING MOSSBAUER SPECTROSCOPY AND X-RAY DIFFRACTION

Mössbauer spectroscopy and X-ray diffraction were used to characterize iron oxide mineralogy and AL-substitution of goethite in clays of paddy soils derived from red earth and their original soils (red earth). The results showed that the types and properties of iron oxide minerals in paddy soils derived from red earth were obviously different from those of their parent soils. The main iron oxide minerals of red earth were hematite and high Al-substitutcd (>20 mol%) goethite, but the environments of paddy soil were unfavourable to the formation of hematite which might be transformed to low Al-substituted goethite or other forms of iron oxide after rice planting. The amount of Al-substitution in goethite in P horizon clays of percogenic paddy soil.was higher than that of other diagnostic horizon clays of paddy soil. Small particle, low-substituted(<15 mol%) goethite was the main iron oxide mineral in clays of W horizon in periodically water-logged paddy soil and in G horizon of gleyed paddy soil, no hematite was detected in these clays.The main type of iron oxide minerals and the change of Alsubstitution in goethite of paddy soils derived from red earth reflect the conditions and characteristics of paddy soil, Which are very signnificant for paddy soil classification.