基于中红外光谱的土壤矿物表征及其鉴定

Characterization of Soil Clay Minerals Using Mid-infrared Spectroscopy and the Application in Soil Identification

以3种标准粘土矿物伊利石、高岭石和蒙脱石为材料,研究其中红外光谱(包括透射光谱、衰减全反射光谱和光声光谱)的特征。3种粘土矿物的中红外透射光谱均存在3个主要的吸收区域(3000~3800 cm-1,1300~1800 cm-1和500~1200 cm-1),且吸收特征明显不同;3种粘土矿物的中红外衰减全反射光谱的差异主要表现在800~1200 cm-1,其他区域差异不明显;而3种粘土矿物的中红外光声光谱特征与透射光谱相近,但3个吸收区域具有更丰富的吸收特征。应用中红外光声光谱分析表明,海伦黑土为富含蒙脱石的偏中性土壤,长武黄土为富含蒙脱石或伊利石的碱性土壤,而祁阳红壤为富含高岭石的酸性土壤。

Characterization of three source clay minerals,illite,kaolin and montmorillonite,were made using three mid-infrared spectroscopic techniques(attenuated total reflectance(FTIR-ATR),transmittance spectroscopy,and photoacoustic spectroscopy(FTIR-PAS)).For the FTIR transmittance spectra,there are three main absorption regions: 3 000～3 800 cm-1,1 300～1 800 cm-1,and 500～1 200 cm-1,and sharp differences can be found in each region.For the FTIR-ATR spectra,there are absorptions with main difference in the region of 800～1 200 cm-1.For the FTIR-PAS spectra,there are also three similar absorption regions as FTIR transmittance spectra.However more information is found in the FTIR-PAS spectra comparing with FTIR transmittance absorptions.The FTIR-PAS was applied to identify three soil types and the results revealed that: Hailun soil was characterized as montmorillonite type soil with medium calcium carbonate content,Changwu soil was characterized as montmorillonite/illite type soil with high calcium carbonate content,and Qiyang soil was characterized as kaolin type soil with low calcium carbonate content.