厦门湾空气质量对新冠疫情管控的响应

Response of Air Quality to COVID-19 Lockdown in Xiamen Bay

通过对厦门湾城市群在COVID-19封锁前后6周内(2020-01-11~2020-02-21)的空气污染物浓度变化进行分析,以确定影响本区域空气质量的主要人为污染源.在春节假期与封锁叠加期间,SO_(2)、NO_(2)、CO、PM_(10)和PM_(2.5)浓度相比于节前1周的下降幅度分别为6%~22%、53%~70%、34%~48%、47%~64%和53%~60%,而O_(3)浓度变化没有一致的规律性;与2018~2019年历史同期相比,PM_(2.5)、PM_(10)、CO和NO_(2)的下降幅度更大,但SO_(2)的下降幅度相当;在复工复产后,NO_(2)的反弹幅度最大(38%~138%),远高于SO_(2)(2%~42%),显示交通源相对于固定源更易受到疫情管控的影响;春节后风速增大和降水增多也为SO_(2)、NO_(2)和PM的下降提供了正向影响.利用反距离插值权重法,得到管控前后厦门湾城市群不同污染物的空间分布变化特征,显示NO_(2)浓度高值区的变化与交通源高度相关,CO和SO_(2)空间分布特征保持稳定,复工后PM_(2.5)和PM_(10)在人口与路网密集区变化不明显,而在工地相对集中区域有明显上升,O_(3)空间分布的低值区与NO_(2)的高值区具有较好的空间匹配性,显示NO_(2)对O_(3)滴定作用明显,可为进一步O_(3)污染减排措施的制定提供参考.

Air pollutant concentrations in the Xiamen Bay cities during the period before and after COVID-19 lockdown(from January 11 to February 21,2020)were studied to determine the influence of human activities on air quality in this region.During the Chinese Spring Festival holiday and the lockdown period,the concentrations of SO_(2),NO_(2),CO,PM_(10),and PM_(2.5)decreased by 6%-22%,53%-70%,34%-48%,47%-64%,and 53%-60%,respectively.However,the changes in 03 concentrations were not consistent with the variations of human activities.The reduction rates for PM_(2.5),PM_(10),CO,and NO_(2)during the Spring Festival were greater than in previous years(2018 and2019),but the reduction rates for SO_(2)were comparable.The concentrations of NO_(2)increased sharply(38%-138%),and much higher those of SO_(2)(2%-42%),after the resumption of socioeconomic activities,indicating the importance of traffic reductions due to the lockdown measures on NO_(2).Higher wind speeds and rainfall after the Spring Festival were also favorable for the decline of SO_(2),NO_(2),and PM.The spatio-temporal distributions of the six criterial pollutants in the Xiamen Bay city cluster were obtained based on the Inverse Distance Weight method.The variability in regions with high NO_(2)concentrations was strongly linked to traffic emissions,while spatial patterns for CO and SO_(2)changed little over the six-week study period.The concentrations of PM_(2.5)and PM_(10)increased notably in the region,linked to more construction activity,but changed comparatively little in regions with dense populations and traffic networks.03 remained relatively stable but low-value regions corresponded to those regions with high NO_(2)concentrations,indicating the significant titration effect of NO_(2)on O_(3).These results provide valuable information that can inform O_(3)pollution reduction measures.