Saltas V, Triantis D, Manios T, Vallianatos F
Department of Natural Resources and Environment, Technological Educational Institute of Crete, Chania, Crete, Greece.
Environ Monit Assess. 2007 Oct;133(1-3):69-78. doi: 10.1007/s10661-006-9560-7. Epub 2006 Dec 14.
In the present work, dielectric measurements were performed in plane-tree leaves collected from a polluted urban site and a natural unpolluted one, in order to investigate the sensitivity of dielectric relaxation spectroscopy to the detection of heavy metals pollution. Although heavy metal concentrations at the urban site are not found considerable higher than those at the natural site, the two samples exhibit different features in the recorded dielectric spectra. Evaluation of experimental data suggests that the dielectric modulus (M*(omega)) representation is the most suitable for accenting the different dielectric relaxation processes of each sample. The imaginary part of dielectric modulus M''(omega) was fitted using a three-term Havriliak-Negami relaxation function, with fitting parameters, which depend on the concentrations of heavy metals. The lower frequency relaxation process is attributed to the ionic conductivity of the samples, while the two others are due to different charge transport mechanisms of alpha-response. The investigation of plane-tree leaves in terms of their dielectric properties can be considered as a promising biomonitoring for environmental pollution.
在本研究中，对从污染的城市地点和天然未污染地点采集的悬铃木树叶进行了介电测量，以研究介电弛豫光谱法对重金属污染检测的灵敏度。尽管城市地点的重金属浓度并未显著高于天然地点，但两个样品在记录的介电谱中表现出不同的特征。对实验数据的评估表明，介电模量（M*(ω)）表示最适合突出每个样品不同的介电弛豫过程。介电模量M''(ω)的虚部使用三项Havriliak-Negami弛豫函数进行拟合，拟合参数取决于重金属的浓度。低频弛豫过程归因于样品的离子电导率，而另外两个则归因于α响应的不同电荷传输机制。从介电特性方面对悬铃木树叶进行研究可被视为一种有前景的环境污染生物监测方法。
