中文摘要：

针铁矿（Gt）和赤铁矿（Hm）是广泛存在于土壤和沉积物中的重要铁矿物。这两种矿物在土壤和沉积物中含量很低，常规的测试手段很难有效地测定其含量。利用反射光谱联合加热处理的方法，可对土壤及沉积物样品中针铁矿和赤铁矿进行定性或半定量测定。实验结果显示，样品加热到300℃后，针铁矿的反射光谱的一阶导数特征峰发生了变化，赤铁矿的一阶导数特征峰却没有明显的变化。因此加热前后样品反射光谱一阶导数的变化取决于针铁矿和赤铁矿的含量。利用这种方法估计黄土高原第三纪红粘土样品中的赤铁矿含量约为0．3％～0．4％，针铁矿含量约为0．5％～1％。

英文摘要：

Goethite （Gt） and hematite （Hm） are important iron minerals in soils and sediments. However, conventional measurements can not effectively distinguish them in the low concentrations typical of soils and sediments. In this paper we demonstrate that diffuse reflectance spectroscopy （DRS） in conjunction with thermal treatment provides a definitive technique for identifying and estimating concentrations of Gt and Hm in soils and sediments. The DRS pattern of Gt exhibits diagnostic changes of the first derivative value （FDV） peaks after heating to 300℃. Hm can be identified by its FDV peak without heating because it displays no shift in peak wavelength after heating. The degree of thermal change induced in a sample depends on the concentrations of both Gt and Hm. Application of this technique to the samples of the Tertiary red clay from Loess Plateau indicates the concentrations of about 0.3-0.4% for Hm and 0.5-1% for Gt.