石河子市土壤环境磁学特征及空间分布研究

Environmental Magnetic Properties and Their Spatial Variability of Topsoil in Shihezi City

以干旱区新兴绿洲城市石河子市为研究区,采集80个(0~10 cm)表层土壤样品,运用环境磁学方法,对土壤磁性矿物的含量、组成和粒度等参数进行了详细测定和分析.结果表明,石河子市表层土壤磁性特征以亚铁磁性的多畴磁铁矿或磁赤铁矿为主导,同时伴有少量的不完全反铁磁性矿物;从空间分布来看,亚铁磁性矿物含量表现为北部新城区>中心城区>郊区农用地;而磁性矿物颗粒粒度大小依次为北部新城区>郊区农用地>中心城区.磁性矿物的高浓度区与大多数工厂的分布具有一致性;但重化工业集中区(N1~N7)却表现为磁性矿物浓度较低,同时磁性颗粒粒径较大.在研究区内质量磁化(χLF)、饱和等温剩磁(SIRM)和软剩磁(SOFT)是指示工业所在区的有效磁性参数指标,而在化工业集中区需结合磁性粒度参数χFD%进行判别.

The 80 topsoil samples( 0-10 cm) are collected from different land use types in built-up areas,northern new town( including chemical concentration area and concentrated residential areas) and suburban agricultural land at Shihezi oasis city in arid zone of Xinxiang,China. The aim of this study is to analysis the magnetic parameters of concentration,composition and particle size of magnetic properties for the urban topsoils,and to describe the spatial distribution under different circumstances of land use. The magnetic grain parameters show that the soils are dominated with coarser multi domain( MD) ferrimagnetic grain. The magnetic mineralogy parameters suggest that samples are dominated by ferrimagnetic minerals corresponding to magnetite-like minerals,but contain a small amount of anti-ferromagnetic material. From the spatial distribution,the concentration of magnetic minerals are ranked in the order of northern new town > built-up areas > suburban agricultural land. Particle size of magnetic minerals are ranked in the order of northern new town > suburban agricultural land > built-up areas. The high concentration of magnetic parameters areas is coincident with factories' area. However,the magnetic concentration in heavy chemical industry region( N1-N7) are low,and particle size of the magnetic particles is larger. χLF,SIRM and SOFT are effective magnetic parameter indexes indicating the light industrial zone of the study area. While,the discrimination in the heavy chemical industry area needs to combine with a magnetic particle parameters( χFD%).