基于动态污染气团的京津冀地区PM2.5重污染特征及来源模拟

As the most serious polluted area in China, pollution characteristics and source apportionment of PM2.5 in Jing-jin-ji region should be further investigated. In this study, the new and more representative regional PM2.5 heavy pollution characteristics were investigate based on the newly built air quality monitoring network in Beijing and the data sharing high-density monitoring network in Hebei and Tianjin. In addition, a new method was proposed to simulate PM2.5 source based on the dynamic pollution air mass to break the boundaries of administrative divisions. First, the regional PM2.5 heavy pollution processes were screened out based on the monitoring data. Secondly, the Kriging method of ArcGIS spatial analysis tools was applied to obtain the dynamic PM2.5 heavy pollution area and moving path based on the hourly PM2.5 monitoring data. Subsequently, the PM2.5 heavy pollution was divided into accumulation stage, maintenance stage and clearance stage. The WRF/SMOKE/CAMx models and PSAT method were applied to simulate the source of the PM2.5 heavy pollution grids to obtain the contributions of the 13 cities and different emission sources. At last, the regional PM2.5 heavy pollution case database was built and the specific control measures for regional PM2.5 heavy pollution were proposed according to this research.

京津冀地区是目前中国PM2.5污染最严重的区域，有必要对其PM2.5污染特征和来源进行研究。拟基于新建成的北京市空气质量监测网和数据共享的高密度区域监测网，挖掘新的更具代表性的区域PM2.5重污染特征。另外，提出一种新的研究思路，打破行政区划界限，面对动态PM2.5重污染气团进行来源数值模拟。首先根据监测数据筛选出2018-2019年区域PM2.5重污染过程；其次结合逐小时区域PM2.5数据，使用ArcGIS空间分析工具中的Kriging方法进行空间插值，获得动态的区域PM2.5重污染影响范围及移动路径；随后将重污染分为积累阶段，维持阶段和清除阶段，使用WRF/SMOKE/CAMx模型系统的PSAT源示踪技术对受重污染影响的网格进行来源模拟，获得各城市各类排放源对不同阶段的区域PM2.5重污染过程的贡献；最后建立区域PM2.5重污染案例库并提出精细化的区域PM2.5重污染控制措施建议。

基于京津冀地区27个城市的PM2.5监测数据及数值模拟手段，研究了区域PM2.5重污染特征以及污染来源特征。研究发现，2015-2018年四年间共筛选出43个区域重污染过程，平均持续5天，影响19个城市，PM2.5浓度为204 μg·m-3。区域性PM2.5重污染过程起源于保定的概率最高，达到13次，占比达到30.2%；峰值出现在保定的概率最高，发生过11次，占比25.6%；其次为安阳市，发生过9次。将区域重污染过程划分为东南和西南两个通道，西南通道型为京津冀地区PM2.5区域重污染过程的主要类型，2015-2018年分别发生9、7、4和8次，占比分别为56.3%、53.8%、80.0%和88.9%。基于数值模拟的来源解析发现，对区域重污染过程PM2.5浓度贡献最高的城市为保定市，平均贡献为21.9%，其次为石家庄市，平均贡献为16%，区域东部的唐山和区域南部的邯郸贡献也较大，接近10%，京津冀北部地区的承德和张家口贡献较小。