重庆市2015-2020年秋冬季PM_(2.5)污染传输路径与潜在源贡献分析

Transport pathways and potential source contribution of PM_(2.5)pollution in Chongqing from 2015 to 2020

2015-2020年成渝地区各城市PM_(2.5)浓度(国控点监测数据)下降显著,但重庆市、川东北城市群及川南城市群PM_(2.5)污染问题依然存在,且存在一定的传输影响关系.以重庆市为例,使用HYSPLIT模型计算了2015-2020年秋冬季PM_(2.5)污染期间气流后向轨迹,利用轨迹聚类和潜在源贡献算法,分析了不同年份的PM_(2.5)输送特征.结果表明:重庆市PM_(2.5)污染主要受西偏南方向(约占58%,长距离为主)、北偏西方向(约占26%,中距离为主)和南略偏西方向(约占16%,短距离为主)传输影响;川东北城市群和川南城市群对重庆市PM_(2.5)污染传输贡献较为显著,6年平均贡献率分别为23%和15%;不同年份的污染传输贡献差异明显,2015-2017年以川南城市群污染传输为主(平均贡献24%),2018-2020年以川东北城市群污染传输为主(平均贡献37%),川渝以外污染传输影响逐年减弱(平均贡献由33%降至5%).在“成渝双城经济圈”背景下,重庆市与周边川东北城市群及川南城市群建立大气污染联防联控工作机制是深化PM_(2.5)污染防控的有效途径.

According to the PM_(2.5)concentration data from National Air Quantity Monitoring Station Network from 2015 to 2020,it is found the PM_(2.5)concentration in the Chengdu-Chongqing region underwent a substantial decrease. However,the issues of PM_(2.5)pollution still exist in Chongqing,the urban areas of northeast Sichuan and south Sichuan agglomerations. Moreover,there are certain transmissions that interact among them. In this paper,the Hybrid Single-Particle Lagrangian Integrated Trajectory Model(HYSPLIT)was applied to calculate air mass backward trajectory for transmission of PM_(2.5)in different years using the trajectory cluster and potential source contribution analysis(PSCF). PM_(2.5)in Chongqing was mainly transported from the southwest(58%,long-distance),northwest(26%,middle-distance),and south(16%,short-distance). Particularly,the transmission of PM_(2.5)from the northeast and south Sichuan urban agglomerations were more significant,accounting for 23% and 15% of the total amount of transmission for six years respectively. Additionally,the sources of pollution transmission varied obviously in these six years. From 2015 to 2017,the southern Sichuan Basin was the main source of pollution transmission(24% on average);in the next three years,the northeast Sichuan accounted for an average of 37%of the total amount of transmission. Meanwhile,transports influence from outside Sichuan and Chongqing have been weakened in the study period.Thus,it is necessary to establish a joint air pollution prevention and control framework between Chongqing Municipality and the surrounding cities in Northeast Sichuan and Southern Sichuan to abate PM_(2.5)pollution. In specific,under the theme of Chengdu-Chongqing economic circle.