State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
Environ Sci Pollut Res Int. 2017 Nov;24(32):25315-25328. doi: 10.1007/s11356-017-0133-9. Epub 2017 Sep 20.
Environmental magnetism is a simple and fast method that can be used to assess heavy metal pollution in urban areas from the relationships between magnetic properties and heavy metal concentrations. Leaves of Osmanthus fragrans, one of the most widely distributed evergreen trees in Nanjing, China, were collected from four different district types, i.e., residential, educational, traffic, and industrial. The magnetic properties and heavy metal concentrations were measured both for unwashed (dust-loaded) and washed leaves. Scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed that unwashed leaves accumulated much dust due to atmospheric deposition. The value of magnetic properties and heavy metal concentrations in unwashed leaves was significantly higher than those of washed leaves, indicating that these characteristics were mainly derived from atmospheric particulate matter. Saturation isothermal remanent magnetization (SIRM) values obtained from unwashed and washed leaves ranged from 209.14 × 10 to 877.85 × 10 Am kg and from 69.50 × 10 to 501.28 × 10 Am kg, respectively. High concentrations of heavy metals, such as Pb and Fe, the Tomlinson pollution load index, and the SIRM of unwashed leaves occurred in the traffic and industrial districts. A preliminary principal component analysis identified the source categories and suggested that industrial activities may be more related to the release of particulate matter rich in Fe. The heavy metal concentrations and pollution load index showed significant positive correlations with the low-frequency magnetic susceptibility and SIRM of unwashed leaves, indicating that these properties can be used to semi-quantify atmospheric heavy metal pollution. Our study suggests that it is possible to employ magnetic measurements as a useful tool for the monitoring and assessment of atmospheric heavy metal pollution.
环境磁学是一种简单快速的方法，可以通过磁学性质与重金属浓度之间的关系来评估城市地区的重金属污染。从中国南京分布最广的常绿树种之一桂花的叶片中，采集了来自四个不同区域类型（居民区、教育区、交通区和工业区）的样本。对未清洗（负载灰尘）和清洗后的叶片进行了磁性和重金属浓度的测量。扫描电子显微镜结合能量色散 X 射线光谱证实，由于大气沉积，未清洗的叶片积累了大量灰尘。未清洗叶片的磁性和重金属浓度值明显高于清洗叶片，表明这些特征主要来源于大气颗粒物。未清洗和清洗叶片的饱和等温剩磁（SIRM）值分别为 209.14×10 到 877.85×10 和 69.50×10 到 501.28×10 Am kg。交通和工业区的未清洗叶片中重金属浓度较高，如 Pb 和 Fe，汤姆林森污染负荷指数和 SIRM 较高。初步主成分分析确定了污染源类别，并表明工业活动可能与释放富含 Fe 的颗粒物有关。未清洗叶片的重金属浓度和污染负荷指数与低频磁化率和 SIRM 呈显著正相关，表明这些性质可用于半定量大气重金属污染。我们的研究表明，磁测量可以作为监测和评估大气重金属污染的有用工具。
