珠江三角洲地区冬季硫、氮干沉降的来源解析

采用WRF-CMAQ模式对珠江三角洲地区2015年1月进行数值模拟，结合CMAQ的集成源解析方法ISAM对S、N及其干沉降的来源贡献进行分析.结果表明：珠江三角洲地区S、N干沉降量高值主要分布在广佛交界处以及珠江口附近，其逐日变化趋势主要受质量浓度变化影响，但在部分时间段受干沉降速率的影响亦相当显著.珠江三角洲区域内排放源对于S干沉降的平均贡献占比为36.2%，与其质量浓度区域内贡献占比相当，SO₂干沉降速率增加以及背景风场变弱会使区域内贡献占比增加；区域内源对于N干沉降的平均贡献占比为32.4%，远小于其质量浓度区域内贡献占比，当NO₂质量浓度减少，使得HNO₃的质量浓度和干沉降量减少时，区域内贡献占比增加.对于珠江三角洲典型城市，广州S干沉降的本地贡献为27.7%，N为14.2%；江门S干沉降的本地贡献为9.6%，N为8.8%.2个城市对比而言，广州受本地的影响较江门显著，江门受其上风方向广州和佛山两市输送的影响显著，但当背景风场减弱时，江门本地贡献会有明显增加.

Source apportionment to dry deposition of sulfur and nitrogen in winter in the Pearl River Delta region

The WRF-CMAQ modelling system was used to simulate dry deposition of S and N in the Pearl River Delta (PRD) region in January 2015, and CMAQ Integrated Source Apportionment Method (CMAQ-ISAM) was utilized to investigate their source apportionment. The results indicated that the high levels of dry deposition of S and N were occurred mainly in the junction of Guangzhou and Foshan and Pearl River Estuary (PRE). Their daily variation trend was mainly affected by mass concentration, but it was also significantly affected by dry deposition velocity during certain periods. The contribution of local source to dry deposition of S in PRD was 36.2%, which was the same as mass concentration of S. The contribution of local source would increase with the increasing of SO₂ dry deposition velocity and the weakening of background wind field. The contribution of local source to dry deposition of N in PRD was 32.4%, which was much less than that of mass concentration of S. The contributions of local source would increase with the reducing of mass concentration and dry deposition of HNO₃. In Guangzhou, the contributions of local source to dry deposition of S and N were 27.7% and 14.2%, respectively. In Jiangmen, the contributions of local source to dry deposition of S and N were 9.6% and 8.8%, respectively. Guangzhou was mainly affected by local pollutants compared to Jiangmen, which was affected basically by pollutants transportation from Guangzhou and Foshan. When the background wind field was weakened, the contribution of local source in Jiangmen increased significantly.