Quantification and Semi-quantification of Iron-oxide Minerals in Aerosol Particles in the Hinterland of Taklimakan Desert
By scattering and absorbing solar and telluric radiation,dust aerosol has a direct impact on the Earth's radiative balance.Their quantification is of utmost importance to assess the desert dust optical properties.Iron oxides minerals(especially hematite and goethite) contents are very low in aerosol particles,which are strong absorbers at ultra-violet and visible wavelengths.CBD method and diffuse reflectance are adapted to quantify and semi-quantify the free-iron oxides contents in the aerosols collected at Tazhong on 9-11 April,2006 in the Hinterland of Taklimakan Desert.For these samples,the percentage of free-iron relative to the total estimated aerosol mass increased from 4.55% to 8.16% with an average of 6.36%.Total-iron content,free-iron content and free-to-total iron ratio are 5.16%,and 0.32%,respectively.The first derivatives of the reflectance spectra are consistent with signals from two iron-oxide minerals,hematite and goethite,at wavelengths of 560 nm and 435 nm,respectively.