粉煤灰堆场重金属污染的磁学响应及诊断机理

Fly-ash deposites on soils over a large area surrounding and enrichs in soil sufrace and transfers in deep characterized by their small particle size, low density, large quantity and high atmospheric mobility. Routinely used geochemical methods are rather time consuming, expensive, laborious in terms of sample preparation and analysis. The study delineate the heavy metals and magnetic distibution of based on the magnetic properties of soils, sediments, dust and plants from fly ash yard and recognize the sources and reveal diagnosis mechanism, We are trying to document that simple and fast magnetic measurements can reflect, under certain circumstances, the anthropogenic input of certain heavy metals. Scanning electron microscope with EDX and rock magnetic test are performed to recognize the pollution sources; By tracing and extracting magnetic information on enrichment, migration and transformation of heavy metals releasing from fly ash, the pollution diagnosis mechanism are revealed with simulated acid rain treatment; Statistical relationship between magnetic susceptibility and the concentration of pollutants is discussed and the environment significance is revealed. This study aims to investigate the validity of this method for quantifying the environmental pollution state, which will finally provide a new, fast and effective way for large-scale applications in the field of heavy metal pollution assessment.

粉煤灰具有粒径细、密度小、数量大、容易随风飘散等特点。导致露天堆场粉煤灰呈现大范围、大区域扩散且极易在土壤表层富集并向深层迁移。使得常规采样及分析凸显出系列弊端（耗时、昂贵、繁琐）。而环境磁学作为一种简便、快捷、经济的监测手段，在环境监测领域中的应用受到广泛、重视。开展粉煤灰及堆场周围土壤、沉积物及植物中重金属的分布、富集、污染来源的磁学解析、迁移过程中磁控机理及重金属污染磁指示的可行性研究。获取不同介质中重金属及其结合态和磁性分布特征；结合电镜扫描、能谱分析等手段，识别重金属污染的磁来源；跟踪自然及模拟酸雨条件下粉煤灰迁移过程中磁性矿物、重金属及其结合态迁移、转化，探讨磁性矿物形态转化对重金属的控制机理；揭示重金属污染与磁学指标之间的联系及环境意义，筛选反映粉煤灰堆场重金属污染的磁诊断指标，探索利用磁参数指示重金属污染的可行性，为露天粉煤灰堆场环境重金属污染监测提供快速、有效的新手段。

选取某粉煤灰堆场周围土壤为主要研究对象，借助环境地球化学、环境磁学测试及数理统计等综合分析，通过提取污染土壤中“粉煤灰外源入”导致重金属与磁学特性在发生、迁移等过程中发生的变化，揭示两者之间迁移、转化规律，阐明磁性矿物的转化对重金属的控制机理。1#和2#剖面上部亚铁磁性矿物和部分重金属富集在一起，浓度较高，而在剖面下部主要与成土母质共生,浓度相对较低且稳定,与实验室模拟酸雨淋溶粉煤灰重金属迁移过程基本保持一致；通过数理手段统计结果表明:剖面重金属（主要为Cu, Pb, Cd and Zn）和磁指标（χ、SIRM、ARM）相关性显著。对土壤表层提取物进一步开展岩石磁学和电镜扫描结果例证了表层富集的污染的主要共同来源,表明磁学参数可以作为重金属污染监测的一个有效手段。