城市道路区土壤的磁学性质及其发生学意义

MAGNETIC PROPERTIES OF URBAN SUBGRADE SOIL AND THEIR PEDOGENETIC IMPLICATIONS

土壤磁学性质测定简便快捷,且具有特定的土壤发生学意义。本研究以南京市主城区11个道路土壤剖面共63个样品为研究对象,通过对低频磁化率和频率磁化率2个常用磁学性质以及土壤游离铁、活性铁、颗粒组成、有机碳、pH、碳酸钙相当物等土壤发生学特性的测定和相关性统计分析,结果表明:城市道路土壤磁性矿物来源和成土过程具有多样性;磁性矿物主要来源于燃煤飞灰、汽车尾气中的粗粒磁性矿物,其中可能伴生污染物质的输入;较高的pH和碳酸盐不利于细粒磁性矿物的形成。城市土壤磁学性质与其他发生学特性的系统研究,有利于阐明城市土壤的形成过程。

Magnetic properties can be simply, rapidly and accurately measured, and their pedogenetic implications are significant. In this study, 63 soil samples collected from ll subgrade soil profiles distributed in the downtown area of Nanjing were tested for low-frequency susceptibility, frequency dependent susceptibility, free iron oxide, active iron oxide, particle size distribution, organic carbon, pH and calcium carbonate equivalents. Results show that magnetic mineral and soil-forming processes were highly diversified due to heterogeneity of parent materials and artificial input. Magnetic minerals were mainly derived from fly ash, automobile exhaust and so on. High pH and carbonate content retarded formation of fine magnetic minerals in urban environment. Magnetic susceptibility combined with other pedogenetic properties is very useful in illustrating the soil-forming processes in urban areas.