水田、旱地土壤重金属磁学响应及相关监测研究

Magnetic response of heavy metals in paddy and drylandsoils and the related monitoring research

为研究水田-旱地土壤中重金属磁学响应差异及原因,采集广州市有代表性的2种土壤样品各70组并进行检测.磁学测试结果显示,土壤中磁性矿物主要为软磁性亚铁矿物及少量硬磁性矿物.旱地土磁性整体略强于水田,水田土中含有反铁磁性矿物且部分软磁性颗粒溶解.2种土壤中单畴、多畴颗粒以及旱地土超顺磁颗粒形成于成土风化作用,而水田土超顺磁颗粒形成受其他因素影响.成土过程磁性矿物产生顺序依次为成土磁铁矿、磁赤铁矿、赤铁矿、针铁矿.土壤中重金属含量与磁学参数存在相关性,但多数重金属和磁性颗粒来源并不一致.尽管如此,土壤按重金属富集程度分类进行回归分析得到的方程大部分效果很好,该磁学手段能用于水田-旱地土壤重金属监测.

To study the difference and cause of magnetic response of heavy metals in paddy field and dryland soil,70 representative soil samples from Guangzhou were collected and tested.The magnetic test results showed that the magnetic minerals in the soil were mainly soft magnetic ferrous minerals and a small amount of hard magnetic minerals.The magnetism of dryland soil was slightly stronger than that of paddy field,which contained antiferromagnetism minerals and some soft magnetic particles were dissolved.Single domain and multi domain particles in the two soils and superparamagnetic particles in dryland soil were formed by soil forming weathering,while superparamagnetic particles in paddy soil were formed by other factors.The sequence of magnetic minerals during weathering and pedogenesis was pedogenic magnetite,maghemite,hematite and goethite.There was a correlation between the content of heavy metals in soil and magnetic parameters,but the sources of most heavy metals and magnetic particles were not consistent.However,most of the regression analysis equations obtained by classifying soil according to the degree of heavy metal enrichment were effective.And magnetic methods could be used to monitor heavy metals in paddy and dryland soils.