城市地表灰尘的分形特性分析

Fractal Characteristic Analysis on Urban Surface Dust

城市地表灰尘在城市环境中无处不在,其对人体和环境造成危害的程度与灰尘颗粒物的粒径有着直接关系。本文运用分形和多重分形的方法探讨了采样区地表灰尘粒径分布特征,发现城市地表灰尘颗粒分布较分散,但也存在颗粒分布相对集中且较粗的特点;地表灰尘粒径分布、pH值以及有机质含量受城市功能区划影响;熵维数D1和熵维数/容量维数D1/D0与城市地表灰尘的pH值成负相关,与有机质含量成正相关,分维数D与pH值及有机质含量之间无相关性。多重分形参数比简单的分维数更能表征地表灰尘颗粒的分布特征,能够提供更多的信息。

Urban surface dust in urban environment is ubiquitous, whose grain-size directly correlate with the harm degree to human and environment. This paper discussed the characteristic of surface dust grain-size distribution in the sampling area by utilizing fractal and multifractal methods and discovered that the distribution of urban surface dust particles was scattered, but concentrated and coarse, the urban functional zoning had influence on the surface dust grain-size distribution, pH and organic matter; the entropy dimension D1 and entropy dimension/capacity dimension D1/D0 were positively correlated with organic matter content but negatively correlated with pH value, there was no correlation between fractal dimension and pH value or organic matter content. The parameters of multifractal can provide more information about the distributed characteristic of urban surface dust than fractal dimensions