新冠肺炎疫情时期四川盆地大气污染成因分析  

Analysis of air pollution in the Sichuan Basin during the COVID-19 pandemic

作　　者：黄鉴涛 刘婧懿 徐家炜 周德荣[1] 黄昕[1] HUANG Jiantao;LIU Jingyi;XU Jiawei;ZHOU Derong;HUANG Xin(School of Atmospheric Sciences,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学大气科学学院,南京210023

出　　处：《气象科学》2022年第3期377-389,共13页Journal of the Meteorological Sciences

基　　金：国家重点研发计划项目(2016YFC0202000);国家自然科学基金资助项目(41922038);江苏省PM_(2.5)和臭氧污染协同控制重大专项。

摘　　要：由于新型冠状肺炎病毒(COVID-19)的爆发,中国从2020年春节起实施了限制出行、交通管制等一系列措施,污染物排放量大幅度减少,但四川盆地区域仍出现了多次轻度空气污染事件。本文结合空气质量观测数据与WRF-Chem模式模拟分析了疫情封控减排时期四川盆地污染的时空分布及成因。四川盆地区域二氧化氮(NO_(2))因人为活动减排从35.0μg·m^(-3)下降至20.2μg·m^(-3),减少比例约为40%~60%,而臭氧(O_(3))因NO_(X)-VOCs-O_(3)的非线性关系以及四川盆地区域氮氧化物(NO_(X))、挥发性有机物(VOCs)排放与减排的不均衡反而从27.5μg·m^(-3)上升至41.4μg·m^(-3),在重庆甚至增幅高达100%,进而促进了四川盆地区域气态污染物的氧化和二次细颗粒物的生成。疫情减排对污染的影响存在较为显著的区域差异,在成都、重庆地区,二次污染的生成一定程度上抵消了一次污染物减排的影响,二次污染物与一次污染物的比例变化幅度为-10%~20%,而在南遂广、川南、达万区域,细颗粒物(PM_(2.5))平均质量浓度从57.0μg·m^(-3)降低至47.4μg·m^(-3),二次污染物与一次污染物的比例下降幅度约为30%~60%。总体而言,减排在疫情期间发挥主导作用,不平衡的一次减排和大气氧化性的增强促进了部分区域二次污染物生成过程,四川盆地区域的污染防治仍需注重多种污染物的协同治理。After the outbreak of Corona Virus Disease 2019(COVID-19),multiple measures have been implemented to slow down the spread of virus,including travel restrictions and stay-at-home order,since the Chinese New Year 2020,leading to a huge reduction of the primary emission.However,several air pollution events still occurred in the Sichuan Basin.By combining in-situ observation and WRF-Chem simulations,this work aims to explore the cause of the air pollution during the lockdown period in the Sichuan Basin.Due to substantial transportation emission reduction,NO_(2) concentration was significantly reduced from 35.0μg·m^(-3) to 20.2μg·m^(-3) in the Sichuan Basin area,dropping about 40%-60%.Spatially,there existed regional disparities in the change of O_(3) concentration because of the NO_(X)-VOCs-O_(3) non-linear relationship and the unbalanced emission reduction of NO_(X) and VOCs in the Sichuan Basin.During the lockdown,O_(3) concentration in this region increased from 27.5μg·m^(-3) to 41.4μg·m^(-3) with the maximum increase reached 100%in Chongqing,and it enhanced secondary aerosol formation by increasing the atmospheric oxidation capacity.In the Chengdu and Chongqing area,the increasing of O_(3) and atmospheric oxidation capacity promoted secondary aerosol formation,which somehow counteracted the primary pollution reduction.Meanwhile,in the other area of the Sichuan Basin,a decreasing O_(3) and atmospheric oxidation capacity suppressed the secondary formation,and the mean PM_(2.5) concentration reduced from 57.0μg·m^(-3) to 47.4μg·m^(-3).The rate of secondary and primary pollution changed about-10%to 20%in Chengdu and Chongqing area,and it decreased 30%-60%in the other area of the Sichuan Basin.In conclusion,the unbalanced primary emission reduction and the increasing atmospheric oxidation capacity favored the secondary pollution formation,which highlights that air quality control in the Sichuan Basin requires a coordinated and balanced control of multiple pollutants.

关 键 词：新冠肺炎疫情 减排 PM_(2.5)污染 O_(3)污染 WRF-Chem模拟 

分 类 号：X51[环境科学与工程—环境工程]