西安市街道灰尘磁化率特征及其污染指示意义

以磁学参数作为环境重金属污染的一项指标,对西安市街道灰尘进行了系统的采样和测定.结果显示,磁化率可以反映西安市的整体污染水平.街道灰尘磁化率值较高、频率磁化率较低,二者呈显著负相关,表明街道灰尘磁性增强源于人类活动影响.磁化率随温度变化曲线表明,受电厂影响的样品主要含磁铁矿,而污染源较复杂的样品则含有磁赤铁矿、赤铁矿以及少量铁单质.磁化率与交通污染导致的Pb、Ba等元素及冶金行业带来的Cu、Cr等元素间有较好的相关性,表明西安市主要污染物来自交通污染及冶金行业排放.在局部范围内,磁化率与元素的相关性随元素种类的不同而具有明显的差异,表明不同区域内导致磁化率升高的人为活动存在差异.

Magnetic susceptibility of the dust of street in Xi'an and the implication on pollution

With the aim at investigating the distribution of pollution in Xi'an city,a systematical sampling of street dust was carried out.Rock magnetic measurement showed the street dust had a high magnetic susceptibility and low frequency dependent susceptibility.Their obviously negative correlation indicatd that the magnetic enhancement mainly attribute to the human activity.Thermomagnetic analysis indicated that the samples affected by electricity generation station were dominated by magnetite,while samples influenced by several sources had maghemite,hematite and little amount of pure iron as their dominant magnetic minerals.Statistical analysis exhibited a great positive correlation between the magnetic susceptibility and elements like Pb and Ba which attribute to the traffic,pollution and elements like Cu and Cr which were resulted by metallurgic industry.Pollution in Xi'an city mainly attribute to the traffic pollution and metallurgic industry,and magnetic susceptibility could be used to reflect the intensity of pollution.Besides,magnetic susceptibility displayed a different correlation with different element in different districts.And this may indicate that the human activity that caused magnetic enhancement was different in each district in the city.