许昌市路尘磁化率空间分布特征及 其污染指示意义

利用Bartinton MS2型双频磁化率仪对许昌市的路尘磁化率进行了研究，结果表明：1）许昌市城区路尘磁化率在98.33×10-8~600.92×10-8 m3/kg，平均值为319.72×10-8 m3/kg，频率磁化率在0.20%~5.94%，平均为1.92%，这种高磁化率值和低频率磁化率组合表明路尘中超顺磁颗粒含量较少，磁化率的高值主要是由于人为活动产生的磁性颗粒沉积造成的。2）路尘磁化率空间上具有从西北向东南递减的趋势，这主要与该城市功能分区、人口密度、交通流量和环境绿化情况有关。位于西北部的铁西片区和旧城区人口密度大，车流量大，并分布有一些工业企业，环境污染严重，路尘磁化率最高；东城区、高新技术开发区和城南片区环境质量均较好，这些区域路尘磁化率均较低。3）在商业中心、交通环岛和高速公路入口等处由于交通流量大，路尘磁化率值出现高出周围地区的现象。通过本文研究证明了利用路尘的磁化率特征可以直观地反映出城市的污染状况。

Spatial Distribution of Road Dust Magnetic Susceptibility of Xuchang and Its Pollutional Implications

The use of magnetic susceptibility characteristics of the urban road dust to reflect the city's pollution is an important part of the environmental magnetic studies. The results of road dust magnetic susceptibility of Xuchang city show that: Road dust magnetic susceptibility ranges from 98.33～600.92×10-8 m3·kg-1, and the average value is 319.72× 10-8 m3·kg-1, frequency magnetic susceptibility ranges from 0.20～5.94%, with an average of 1.92%. The high magnetic susceptibility values and the low frequency magnetic susceptibility suggest that road dust has less super paramagnetic particles content, and the high magnetic susceptibility is mainly caused by the magnetic particle deposition due to human activities. Spatial characters of road dust magnetic susceptibility display a decreasing trend from northwest to southeast, which mainly caused by the city's function zoning, population density, traffic flux and environmental quality. The road dust samples of Tiexi District and the Old District have the highest magnetic susceptibility values, reflecting the serious environmental pollution that caused by high population density, heavy traffic flux and industrial activities. In East District, High-tech Development District and Southeast District the road dust magnetic susceptibility values are lower, indicating the better environmental condition. Moreover, due to the heavy traffic in the commercial centers and the freeway entrances, road dust magnetic susceptibility values are higher than those in surrounding areas. The magnetic susceptibility characteristics of road dust can intuitively reflect the pollution of the city.