不同类型降雨公路径流中颗粒粒径及污染物的分布特性

Distribution characteristics of particle size and pollutants in road runoff during different types of rainfall

在对南京机场高速禄口高架桥段雨天路面径流水质进行连续监测的基础上,考察了不同粒径段颗粒分布,重点分析了颗粒粒径分布随径流过程的变化特征及其与污染物分布的关系,并探讨了温度和pH值对粒径分布的影响.结果表明,径流中粒径小于75μm的颗粒较多,其中0.45～20μm粒径段的颗粒最多,占总颗粒的37.5%.小雨事件中,粒径小于等于75μm的颗粒体积在径流过程的前40 min内波动较明显;中雨事件中,粒径小于等于150μm的颗粒在径流过程的前40 min内变化较明显;大雨事件中,粒径小于等于150μm的颗粒在径流过程的前30 min内体积变化明显.各粒径段小颗粒(≤150μm)与对应粒径段颗粒中COD及TP的相关性均显著于大颗粒(>150μm)的,且21～75μm粒径段颗粒对COD及TP吸附与富集的能力较为突出.温度对0.45～20μm及大于300μm的颗粒粒径分布的影响较明显.pH值对21～75μm及76～150μm粒径段的颗粒粒径分布的影响显著.

Based on the monitoring of runoff water quality on the surface of Lukou section of Nanjing Airport Expressway,the distributions of particles with different sizes are evaluated.The emphasis is placed on the variation characteristics of particle size distribution in runoff and the relationship between particle size distribution and pollutants.The impact of temperature and pH on particle size distribution is also explored.The results show that the particles with size less than 75μm are more in the runoff,especially the particles with size from 0.45 to 20μm are much more,being 37.5% of the total particles.The volume of particles with size no more than 75μm fluctuates in the initial 40 min of runoff during smaller rainfall event.During the medium-rainfall event,particle volumes with size less than and equal to 150μm vary obviously in the initial 40 min of runoff.In terms of large rainfall events,particles with size less than and equal to 150μm vary more obviously in the initial 30 min settling.The correlation of smaller particles（≤150μm） with the levels of COD and TP contained in the particles is more significant than that of larger particles（150μm）,and the adsorptive capacity of COD and TP by the particles with sizes of 21 to 75μm is more prominent.Particle distribution with size from 0.45 to 20μm and larger than 300μm is significantly influenced by temperature in runoff.The pH value has a significant impact on the particle distribution with size from 21 to 75μm and from 76 to 150μm.