基于走航观测的长江三角洲地区大气污染特征及来源追踪

为了加强对长江三角洲地区大气污染分布特征和输送规律的认识，利用移动车载设备开展了不定期的走航观测，重点研究了2016-2018年冬季灰霾污染和春季光化学污染条件下长江三角洲地区的大气污染特征.结果表明，走航观测期间长江三角洲地区PM_2.5日均浓度为60~122 μg/m³，东部的常州、无锡一带，西部的合肥、芜湖地区，北部蚌埠、滁州一带，南部湖州、杭州地区的PM_2.5浓度较高，比其他地区高出20%~40%.O₃日均浓度水平为9~52 μg/m³，苏州、盐城、宣城与湖州地区浓度相对较高.运用FLEXPART_WRF模式，结合PM_2.5排放清单，分析了走航观测期间长江三角洲地区及沿线城市PM_2.5的潜在来源.结果发现，东风条件下，南通及上海地区为PM_2.5的潜在源区，北风条件下，连云港、盐城等地区贡献较大.运用FLEXPART前向轨迹计算模块，对一次污染个例过程进行了模拟，并利用走航观测结果进行了验证，发现模拟结果与走航观测结果的相关系数达到0.9.可见，长江三角洲地区存在区域性的PM_2.5和O₃污染，走航观测结合轨迹分析是追踪污染气团输送的有效手段.

Air pollution characteristics and source tracking in the Yangtze River Delta based on cruise observation

To enhance our understanding of the distribution and transport of air pollution in the Yangtze River Delta (YRD) region, cruise measurements were carried out in the YRD. We focused on winter haze pollution and spring photochemical pollution over 2016~2018. It was showed that the PM_2.5 concentrations in the Yangtze River Delta ranged between 60 and 122μg/m³, varying largely with location. In the Wuxi-Changzhou area in the east of YRD, the Wuhu-Hefei area in the west, the Bengbu-Chuzhou area in the north, and the Huzhou-Hangzhou area in the south, the PM_2.5 concentrations were 20%~40% higher than other regions. The concentrations of O₃ were 9~52μg/m³ with unnoticeable spatial variation. The concentrations of ozone in Suzhou, Yancheng, Xuancheng and Wuhu were relatively high. We further used the FLEXPART_WRF model combined with the PM_2.5 emission inventory to explore the possible sources of PM_2.5 in the YRD. We found that Nantong and Shanghai were the potential sources of PM_2.5 when east wind prevails, while Lianyungang and Yancheng contributed more when north wind prevails. We simulated forward trajectories using FLEXPART for a pollution episode. We found the correlation coefficient between the cruise observations and the simulation reaches 0.9. Overall, there still existed regional PM_2.5 and O₃ pollution in YRD region, and cruise observation combined with the trajectory analysis is an effective tool to trace the regional transport of these pollutants.