兰州市室内大气降尘环境磁学特征及其随高度变化研究

对兰州大学齐云楼不同高度的室内大气降尘样品进行的系统环境磁学研究表明,兰州市室内大气降尘中磁性矿物含量较高,并且以多畴和假单畴的亚铁磁性矿物为主,降尘中的磁性矿物主要来自大气污染.兰州市近地表约24 m高度内,室内大气降尘中磁性矿物浓度具有随高度升高而降低、粒径随高度增加而变细的分布特点,称为低污染源决定的近地面吹扬模式.距离建筑物顶部约10 m范围的建筑物内部,随着高度的增加,降尘中磁性矿物浓度增大、粒径变粗,称为高污染源决定的建筑物阻尼模式.兰州市室内降尘的磁性矿物浓度可以有效反映大气颗粒污染状况,研究表明,兰州市距地表20~30 m的适当高度大气颗粒污染最小.研究结果可为了解兰州市大气颗粒污染状况以及开展大气污染治理提供科学依据.

Magnetic Properties of Indoor Dustfall at Different Heights in Lanzhou

Environmental magnetic measurements were carried out on the samples of indoor dustfall collected from Qiyun building at different heights in Lanzhou University. The results indicate a high concentration of magnetic minerals in indoor dustfall, dominated by pseudo-single domain(PSD)and multiple domain (MD)ferrimagnetic minerals which are mainly from air pollution. The concentration and granulometry of magnetic minerals decrease with the increase of the height within 24 m near surface. We call it near surface blowing model dominated by low pollution sources. Within 10 m near the top of the building, the concentration and granulometry of magnetic mineral show the synchronous change with the increase of height and that is called building damping model dominated by high pollution sources. The concentration of magnetic minerals can reflect particulate matter pollution in Lanzhou. The results show the pollution is relatively slight from 20-30 m and can provide a scientific basis for atmospheric dust management and improvement at the same time.