福建三明地区被污染土壤的磁学性质及其环境意义

对福建三明某钢铁厂和火电厂附近的污染表土样品进行了多参数的岩石磁学测试分析，包括χ T曲线、磁滞回线、等温剩磁获得曲线等. 三明地区污染表土中的磁性矿物有磁铁矿、赤铁矿和磁黄铁矿. 样品中磁性矿物的平均粒度较粗，为较大的准单畴，甚至多畴，粒度明显大于成土作用所产生的磁性颗粒. 粗粒的磁铁矿颗粒是污染物的主要磁性组分. 虽然磁化率测量可以作为一种简单、快速而且廉价的检测污染土壤的方法，但同时辅以必要的岩石磁学测量将有利于提取更多的污染信息. 对于低磁化率的污染土壤，亚铁磁性硫化物的存在可以作为土壤可能被污染的证据之一.

Mineral magnetic properties of polluted topsoils: a case study in Sanming city, Fujian province, southeast China

We have conducted mineral magnetic investigations of polluted topsoil samples, which were collected in the vicinity of a steel plant and a power plant in Sanming City, Fujian Province, southeast China. Our analyses include the temperature dependence of magnetic susceptibility, hysteresis loops and isothermal remanent magnetization acquisition curves. High temperature susceptibility measurements suggest that magnetite, hematite and pyrrhotite exist in the polluted topsoil samples. All the samples show multidomain or multidomain like magnetic grain sizes. For the samples with significantly high susceptibility (χ) and low frequency dependent susceptibility (χfd), χ and χfd measurements can be used as an effective method for detecting the polluted topsoils. For the samples with relatively low χ and high χfd, the presence of ferrimagnetic iron sulphide can serve as a potential pollution indicator in the case that an origin from bedrock weathering has been excluded. We further suggest that mineral magnetic measurements can contribute a better and more complete understanding of the pollution processes for industrially polluted topsoils.