空气中PM2.5的扩散和衰减模型

PM2.5的时空分布及其演变规律十分复杂.为刻画PM2.5的发生、扩散和衰减规律,提出点源、线源和面源叠加的多源模型描述区域内的多污染源对某一监测点的影响.考虑风力风速、太阳辐射强度、湿度等天气和季节因素以及重力、湍流扩散、分子扩散等对源强强度的影响,提出源衰减、湿沉积、化学迁移叠加衰减模型,用监测点的PM2.5浓度数据对污染源强度和衰减系数进行反演求解.针对西安市某些监测点处的PM2.5浓度突然增至数倍且延续数小时,建立污染扩散预测与评估方法,对提升前后污染源源强进行分析,给出重度污染区域,并用数据的人工统计定性验证模型的合理性.

The Diffusion and Attenuation Model of PM2.5 Pollution in Air

The time-space distribution and transmutation rule of the PM 2.5 is complex.A model,considering point sources,line sources and plane sources,has been built to illustrate the effect of multiple pollution sources for one monitoring point in an area and to reveal the occurrence,diffusion and attenuation rule of the PM 2.5.The weather and seasonal factors such as the wind velocity,the solar radiation intensity and other factors such as the gravity,turbulent diffusion,molecular diffusion of source intensity have been considered.Models for source attenuation,wet deposition,chemical migration,superposition and attenuation have been combined to calculate the intensity of all sources and the attenuation coefficient,according to the data of different monitoring points.The example of PM 2.5 pollution in Xi'an has been analyzed,of which the data of several monitoring points has been increased suddenly and lasted for several hours.Comparing the source intensity before and after the accident,a heavy pollution area has been predicted and the rationality of the model can be proved by the statistical analysis of the data.