基于CMAQ-ISAM模型的长三角典型城市PM2.5来源解析

大气细颗粒物(PM_2.5)是影响长三角地区空气质量的关键污染物．近年来随着各项环保举措的实施，PM_2.5的来源特征也发生了变化，为了制定切实有效的PM_2.5治理方案，考察PM_2.5的主要来源及其贡献至关重要．本研究使用CMAQ-ISAM模型，定量分析了2018年长三角内4个典型城市(上海、杭州、南京和合肥)PM_2.5的主要来源．表明了上述4个城市PM_2.5的最主要来源:冬季为长三角外的远距离传输(38.5%~52.6%)；秋季为各城市的本地排放(43.0%~50.9%)；在春季和夏季，本地排放是上海、杭州和合肥PM_2.5的主要来源(春季37.1%~53.3%，夏季44.1%~64.7%)，而南京则是周边区域传输 (春季38.5%，夏季46.3%)．针对冬季不同时期的来源解析表明，相较于清洁时期，4个城市在污染时期来自周边区域传输的贡献占比增大，上海、杭州、南京和合肥的增大幅度分别为10.0%、1.5%、8.1%和4.9%，因此开展长三角大气污染区域联防联控具有重要意义． 

Sourcing PM2.5 in cities in the Yangtze River Delta by CMAQ-ISAM

Atmospheric fine particulate matter (PM_2.5) is a key pollutant affecting air quality in the Yangtze River Delta (YRD)．With implementation of various environmental protection measures in recent years, sources of PM_2.5 may have changed．To develop an effective PM_2.5 control strategy, it is vital to identify the main sources of PM_2.5．The CMAQ-ISAM model was used here to analyze quantitatively main PM_2.5 sources in Shanghai, Hangzhou, Nanjing and Hefei in 2018．The major source of PM_2.5 in these 4 cities was found to be long-distance transfer from outside of the YRD region in winter (38.5%-52.6%) but was local emissions in the autumn (43.0%-50.9%)．Local emissions were the main source of PM_2.5 in Shanghai, Hangzhou and Hefei in spring and summer (spring: 37.1%-53.3%; summer: 44.1%-64.7%), but transfer from surrounding areas was the main source in Nanjing in spring (38.5%) and summer (46.3%)．Further source identification in different (clean, pollution) periods within the winter season revealed that, compared with clean period, in the pollution period, contribution ratios from surrounding areas increased, by 10.0%, 1.5%, 8.1% and 4.9% in Shanghai, Hangzhou, Nanjing and Hefei respectively．Therefore it is important to carry out joint preventions and controls both within and without of the YRD region．