第九章 环境物理学 - 北京师范大学精品课程网.ppt

Chapter 9 Environmental physics 9.1 Theory of environmental physics We can see from law of conservation of matter ： The constituents of environment follow the famous law of conservation of matter and continually carrying out matter cycling Each input, output of environment is balanced with accumulation amount. In the environmental system or sub-system, the quality equation can be written as: Accumulation=input-output When the input rate of one system is constant and equals to output rate, the accumulation ratio is zero. This state is regarded as steady state 9.2 Environment atmosphere diffusion theory 9.2.1 The theory basis of atmosphere diffusion Definition: the pollutant discharged into air is transferred, mixed, diluted by air level activity, turbulent flow diffusion activity as well as disturbance activity of different scale of atmosphere; this is regarded as diffusion of atmosphere pollutant. Factors of atmosphere diffusion Power factor Thermal factors Meteorological conditions Factors of atmosphere diffusion Geographical factors Factors of atmosphere diffusion Sea and land breeze：it is caused by the difference of land and sea heat nature. 9.2.2 Turbulent flow diffusion theory Gradient transference theory: it is supposed the dispersion caused by air turbulent flow; it is similar to molecule diffusion and can use the same molecule equation to describe. 9.2.3 The diffusion model of atmospheric pollutants Nature and component of pollutant The pollutant discharged into air generally is composed of each air and solid particle; their natures are determined by their chemical components. The geometry and discharge form of pollution source. Diffusion model of atmospheric pollutant On the basis of plenty inspection date analysis, Gauss used the supposed turbulent flow statics get the diffusion model under normality distribution. Diffusion model Point source diffusion model Point source Gauss model