塔克拉玛干沙漠腹地大气气溶胶中游离氧化铁的测定

大气沙尘气溶胶中铁氧化物含量的测定对研究气溶胶吸收特性有重要的研究意义。采用柠檬酸盐-重碳酸盐-连二亚硫酸盐(CBD)和漫反射光谱法(DRS)对塔克拉玛干沙漠腹地塔中站2006年4月9~11日沙尘暴天气过程前后TSP沙尘样品中的游离氧化铁进行定量和半定量研究,研究得出,塔中游离氧化铁占全铁含量的变化范围在4.55%~8.16%之间(平均值6.36%),全铁占样品总量的5.16%,游离氧化铁占样品总量的0.32%;反射光谱一阶导数曲线峰值在435和560nm对针铁矿和赤铁矿具有识别指示意义。

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.