兰州某钢厂附近土壤磁化率特征及其环境意义

对兰州某钢厂周围土壤进行了磁化率与化学元素分析,采用污染指数评价方法和多元统计发现,表层2cm以内土壤的磁化率显著增高,达到背景值的3.5倍,且频率磁化率相对于深部土壤较低,对比不同位置样点磁化率值,显示钢厂周边土壤受到了钢厂生产排放物的污染.污染主要发生在下风向,且在2km以内最强,污染深度在2cm以内.磁化率与重金属元素含量相关性显著表明磁性矿物与重金属有相同的来源,本研究应用磁化率浓集因子S判别污染程度,结果与内梅罗综合污染指数评价大致相同,因此S可以作为判断这类土壤污染程度的指标.

Measurement of magnetic susceptibility of soil adjacent a steel factory in Lanzhou and its environmental implications

Measurement and analysis of magnetic susceptibility and heavy metal concentrations of soil from a steel factory near Lanzhou City was developed. Results showed that the magnetic susceptibility in uppermost soil horizon (0~2cm) increased significantly relative to the deep soil. The value of susceptibility was 3.5 times of the background, but the frequency magnetic susceptibility was lower relative to the deep soil. The variation of magnetic susceptibility value in the different sampling positions showed that the soil around the steel factory was polluted by the anthropogenic dust input from steel factory. Pollution was mainly found in the downwind direction area, of which the strongest part was in a range of 2 km and a depth of 2 cm. Chemical element analysis showed a strong correlation between the magnetic susceptibility and metals, suggesting they have the same source. Magnetic susceptibility concentration factor (S) was adopted to determine the degree of soil pollution, and the results were basically the same with the Nemerow index. Therefore, S could be used as an indicator to determine the soil pollution.