城市地表磁性筛查与制图及在环境污染监测和城市土壤发生研究中的应用

Magnetic and geochemical characteristics of the topsoils in the whole range of Baoshan District, Shanghai, are screened in situ and mapped, using portable instruments. The spatial correlations between magnetic signals and toxic heavy metal contents are analyzed, and heavily polluted sites in the district are identified and classified. Soil core samples are also collected in a high density to establish semi-quantitative relationships between magnetic signals and toxic heavy metal contents in the polluted sites. This is conducive to implementing in-situ and rapid detection of toxic heavy metals in a range of polluted sites, thus improving the international standards for soil magetometry (ISO/NP 21226). Micro-morphological and mineralogical features of magnetic grains emitted from the different pollution sources are analyzed and compared to establish reference illustrations for identifying and tracking pollutants in the urban soils. Magnetic and geochemical signals in the soil profiles in a high resolution are used to distinguish between polluted soil horizons and natural non-polluted ones, to study the influences of atmospheric deposits and other anthropogenic disturbances on the pedogenesis, development and evolution of urban soils, to set up diagnostic horizons or characteristics of urban soils using magnetic parameters as main indices, and to establish new soil series of the urban soils in Baoshan District, Shanghai, for updating and improving a soil order of Anthrosols in the Chinese Soil Taxonomy.

在上海宝山区全域，用便携式仪器对表土磁化率和地化特性进行原位筛查并制图，分析磁信号对有害重金属元素含量的空间相应，划定污染区域。选择污染小区，进行高密度土壤柱状样采集，建立磁性参数与特定重金属元素含量间的半定量关系，实现污染小区范围内污染元素含量的原位、快速监测，补充和完善土壤磁测法国际标准（ISO/NP 21226）。对不同大气污染源排放磁性颗粒的微形态和矿物学特征进行比较和分析，建立参考图谱，用于城市土壤污染物辨识和追踪。以土壤多剖面高分辨率磁信号和地化信号，区分自然土壤母质层和污染层，揭示大气沉降和各类人为干扰对城市土壤发生、发育和演变的影响；创建以磁性参数为主要指标的城市土壤诊断层或诊断特性，设置宝山区城市土壤土系，丰富和完善中国土壤系统分类人为土纲。

对上海宝山区城市表土网格化采样，进行原位磁性筛查并制图，绘制了城市土壤磁性的空间分布，研究了城市表土磁信号对有害重金属元素累积的空间响应，划定了污染区域。以宝山区石洞口工业区为重点调查区域，采集表土样和土壤柱状样，研究了特定污染小区磁性参数与有害重金属元素含量的定量关系，对土壤磁测法国际标准（ISO/NP 21226）提出了补充和完善建议。在宝山不同功能区的大气悬浮颗粒、大气自然降尘、道路灰尘和城市表土中，均发现人为成因的磁性圆球体；研究了各类磁性颗粒的微形态和微化学特征，判别交通工具释放磁性颗粒的特征，并建立了识别磁性颗粒物源的标准图谱。城市环境人为磁性颗粒普遍存在，正在对城市及周边环境土壤的发生、发育和演化产生持续的重大影响，应认定为一种独特的人为成土作用，建议设立城市土壤磁性诊断特征。