广州市PM_(2.5)污染特征及潜在贡献源区分析

Analysis of the Characteristics and Potential Source Contribution of PM_(2.5) Pollution in Guangzhou

基于NCEP/NCAR全球再分析气象资料和2015-2017年PM_(2.5)浓度,利用HYSPLIT模型研究不同气流轨迹对广州PM_(2.5)浓度的影响,以及污染输送路径和潜在源区空间分布特征。结果表明:(1)广州2015-2017年PM_(2.5)平均浓度为36.5μg/m^3,逐月平均PM_(2.5)浓度1月份最高,为49.3μg/m^3,轻度污染及以上时次比例达15.66%,6月份最低,为20.8μg/m^3,无轻度及以上污染时次。(2)PM_(2.5)平均浓度在不同情景类型下的浓度高低顺序依次为:污染日>干季>清洁日>湿季,其中污染日的PM_(2.5)平均浓度是清洁日的近3倍,干季的PM_(2.5)平均浓度是湿季的1.4倍;不同情景类型下的PM_(2.5)浓度日变化特征基本都在白天时段低(16时最低),晚上时段高(21-22时最高),日变化幅度为污染日>干季>清洁日>湿季。(3)在干季,影响广州的气流轨迹路径主要有5类:东北路径、东南路径、西北路径、西南路径及偏西路径,其中第2类东南路径对广州PM_(2.5)平均浓度的贡献最高;而在湿季,影响广州的气流轨迹路径主要有4类:偏南路径、东南路径、偏北路径及西南路径,其中第3类偏北路径对广州PM_(2.5)浓度的贡献最高。(4)基于潜在源贡献因子和浓度权重轨迹分析法分析表明,广州PM_(2.5)浓度潜在源贡献较大的区域主要集中在广州东部的东莞、惠州、深圳、肇庆、中山等周边地区,该研究可为确定广州污染潜在源贡献区以及区域联防联控提供参考。

Based on the NCEP/NCAR global reanalysis of meteorological data and the PM2.5 concentration during 2015-2017, the influence of different airflow trajectories on the concentration of PM2.5 in Guangzhou, and the spatial distribution characteristics of the transport path and potential source area were studied by using the HYSPLIT model. The results show that average concentration of PM2.5 in Guangzhou during 2015-2017 was 36.5μg/m^3, and the monthly average PM2.5 concentration was the highest in January, which was 49.3μg/m^3. The proportion of mild pollution and above time was 15.66%, and the lowest in June was 20.8μg/m^3, no mild and above pollution times. The order of the average concentration of the average concentration of PM2.5 under different situational types is in order of pollution day > dry season > clean day > wet season. The average concentration of PM2.5 in the day of pollution is nearly 3 times that of the cleaning day, and the average concentration of PM2.5 in dry season is 1.4 times that of the wet season. The diurnal variation characteristics of PM2.5 concentration under different situational types were basically low in the daytime(the lowest at 16:00) and high in the evening(the highest at 21:00-22:00), and the diurnal variation ranges from the pollution day to the dry season, the clean day and the wet season. In the dry season, there are 5 main types of airflow path influencing Guangzhou including northeast route, southeast path, northwest path, south-west path and westward path, of which the southeast routes contribute the highest to the average concentration of PM2.5 in Guangzhou. In the wet season, there are 4 main routes to influence the trajectory of Guangzhou: the south path, the southeast path, the north path and the south-west path, of which the northward route has the highest contribution to the concentration of the Guangzhou PM2.5. Based on WPSCF and WCWT analysis, the region of the potential source of PM2.5 concentration is mainly concentrated in Dongguan, Huizhou, Shenzhen, Zhaoqing, Zhongshan and other surrounding areas in eastern Guangzhou. This study can provide a reference for determining the potential source area of Guangzhou and the joint control of regional joint defense.