Magnetic Characteristics of Topsoil and Leaves in Jinhua City and Their Environmental Indicative Significance

本研究以环境磁学为基础，选取金华市表土和行道树的叶片进行研究，通过磁学分析比表土和树叶的磁性特征，并以数理分析作为补充，揭示金华市土壤污染特征，并为金华市治理环境污染提供新的思路和方法。在金华市二环内同一采样点采集树叶和表土样品各103份，利用环境磁学方法对其进行磁学分析，以得到表土和树叶对环境污染的指示差异。结果表明：(1) 表土样品的磁学特征主要由磁铁矿和磁赤铁矿主导，主要为准单畴和多畴颗粒，工业区和绿化区的土壤污染水平最高，居住区和商业区最低。(2) 树叶样品的磁学特征受亚铁磁性矿物控制，指示工业区和绿化区污染较重，文教区受人为干扰较少。(3) 对比表土和树叶样品，发现两者在工业区和绿化区的磁性矿物含量均较高，但表土在商业区的含量低于文教区，而树叶在文教区的含量低于商业区，这与污染类型和载体特性有关。(4) 表土和树叶均为采样便利的污染载体，能反映短期污染情况。表土对土壤污染指示作用较好，树叶在指示大气污染方面表现优异。结合两种载体可提高监测结果的准确性。This study is based on environmental magnetism, selecting topsoil and leaves of roadside trees in Jinhua City for research. Through magnetic analysis, the magnetic characteristics of topsoil and leaves are compared, and mathematical analysis is used as a supplement to reveal the characteristics of soil pollution in Jinhua City, providing new ideas and methods for environmental pollution control in Jinhua City. 103 samples of leaves and topsoil were collected at the same sampling point within the Second Ring Road of Jinhua City, and magnetic analysis was conducted using environmental magnetic methods to obtain the differences in environmental pollution indicators between topsoil and leaves. The results showed that: (1) The magnetic characteristics of topsoil samples were mainly dominated by magnetite and magnetite, mainly consisting of quasi single domain and multi domain particles. The soil pollution levels were highest in industrial and green areas, and lowest in residential and commercial areas. (2) The magnetic characteristics of leaf samples are controlled by ferromagnetic minerals, indicating heavy pollution in industrial and green areas, and less human interference in cultural and educational areas. (3) Comparing the samples of topsoil and leaves, it was found that both had higher magnetic mineral content in industrial and green areas, but the content of topsoil in commercial areas was lower than that in cultural and educational areas, while the content of leaves in cultural and educational areas was lower than that in commercial areas, which is related to the type of pollution and carrier characteristics. (4) Both topsoil and leaves are convenient pollution carriers for sampling and can reflect short-term pollution situations. Topsoil has a good indication effect on soil pollution, while leaves perform well in indicating atmospheric pollution. Combining two carriers can improve the accuracy of monitoring results.