机动车污染物排放及扩散的时空分布特征研究——以江苏省高速公路网为例

Study on Spatial-temporal Distribution Characteristics of Emission and Diffusion of Vehicular Pollutants:A Case Study of Expressway Network in Jiangsu Province

针对日益严重的高速公路机动车尾气污染问题,基于道路机动车大气污染物排放清单和CALINE-4扩散模式,提出江苏省高速公路网机动车污染物排放及扩散情况的计算方法,并对时空分布特征进行分析。结论如下:(1)在全省路网各类车型结构中,客一对CO和HC的排放总量贡献率最大,分别为41.26%和44.32%;货五对NOx和PM2.5排放总量贡献率最大,分别为33.32%和32.52%。(2)从车辆排放等级来看,客一的国I~国III对CO和HC排放总量的贡献率分别达到73.56%和62.05%;货四和货五的国III对NOx和PM2.5排放总量贡献率分别达到58.73%和63.25%。(3)除NOx之外,其余在预测点的各路段机动车污染物浓度(CO,PM2.5和PM10)均低于《环境空气质量标准》(GB 3095—2012)中的小时平均二级浓度限值,即10 mg/m3,75μg/m3和150μg/m3。(4)从时间分布来看,各类污染物排放量均呈现"双驼峰"变化趋势,即排放峰值出现在9~10点和14~15点,而全省各路段的逐时各类污染物扩散浓度均呈现夜间(22:00—次日4:00)高于白天的时间分布;夜间NOx扩散浓度超过限值(即250μg/m3)的路段占比高达75.2%,尤其在凌晨2:00—3:00点达到峰值。(5)从空间分布来看,北网的CO和HC排放总量小于南网,NOx,PM2.5和PM10则均大于南网,而北网的各类污染物排放强度均明显高于南网;苏北地区的NOx小时平均浓度高于苏南、苏中地区,全天各时段的最大值均出现在"段宅枢纽—新沂东"路段,而最小值主要分布在苏中地区。

Aiming at the growing pollution problem of vehicular exhaust on expressway,based on the emission inventory of road vehicular pollutants and CALINE-4 diffusion mode,the calculation method of vehicular pollutant emission and diffusion on the expressway network of Jiangsu Province is proposed,and its spatio-temporal distribution characteristics are analyzed.It is concluded that(1)In the structure of various types in the provincial road network,Coach Model I has the largest contribution to total CO and HC emissions,which are 41.26%and 44.32%respectively.Truck Model V has the largest contribution to total NOx and PM2.5 emissions,which are 33.32%and 32.52%respectively.(2)In terms of vehicular emission levels,for Coach Model I,the contribution rates of the national stage I-III emission standards to total CO and HC emissions reached 73.56%and 62.05%respectively;for Truck Model IV and V,the contribution rate of the national stage III emission standard to total NOx and PM2.5 emissions reached 58.73%and 63.25%respectively.(3)Except for NOx,the diffusion concentrations of vehicular pollutants(CO,PM2.5 and PM10)at the estimation points in different sections are lower than the lower than the hourly average Grade II concentration limits in Ambient Air Quality Standard(GB 3095—2012),which are 10,75,150μg/m3.(4)In terms of temporal distribution,all kinds of pollutant emission show a"double hump"trend,i.e.,which occurred at 9-10 a.m.and 2-3 p.m.While the hourly diffusion concentrations of various pollutants in different sections in the province show a higher distribution at night(10 p.m.to 4 a.m.the next day).The proportion of road sections where NOx diffusion concentration exceeding the limit at night(250μg/m3)accounts for up to 75.2%,especially reaching the peak value at 2-3 a.m.(5)In terms of spatial distribution,the total CO and HC emissions in the north network are less than that in the south network,the emissions of NOx,PM2.5 and PM10 in the north network are higher than those in the south network,while the emission intensity of all kinds of pollutant in the north network is significantly higher than that in the south network.The hourly average NOx concentration in Northern Jiangsu is higher than that in Southern and Middle Jiangsu,the maximum value of daily periods appears in the Duanzhai Hub-Xinyidong section,while the minimum value mainly distributes in Middle Jiangsu.