Analysis and research on the change of ozone concentration in the near-surface atmosphere during the new crown epidemic in Zhejiang Province

Abstract

With the rapid development of China's economy, ozone pollution has become increasingly serious in many cities and regions. It has become an important air pollutant second only to particulate pollutants. It is a research hotspot in the field of atmospheric environmental chemistry. China has implemented strict control measures, residents' travel and production activities have been strictly restricted, and the intensity of anthropogenic pollutant emissions has dropped to the lowest level in history favorable opportunity.
This study selects Zhejiang Province, relatively developed in the Yangtze River Delta region, as a specific research object. Based on the National Urban Air Quality Real-time Release Platform of China Environmental Monitoring Station monitoring data, 11 major cities in Zhejiang Province(Hangzhou, Jiaxing, Ningbo, Wenzhou, Wenling, Huzhou, Shaoxing, Jinhua, Quzhou, Lishui, and Taizhou) are systematically explored before and after the outbreak of the COVID-19 . The temporal and spatial changes of the near-surface ozone concentration and the number of days exceeding the standard characteristics (including interannual, seasonal, monthly, weekly, and intraday variations). The results show that after the outbreak, the ozone concentration changes at representative sites in cities at the same latitude are consistent with those before the outbreak and still show a gradual increase from west to east. But cities in the same longitude no longer show a decreasing trend from north to south. For the characteristics of the time change, after the outbreak, the difference in ozone concentration between seasons decreased, and the ozone concentration in winter increase, and the peak of ozone concentration appeared on Tuesday or Friday, no longer showing the "weekend effect". At the same time, the ozone concentration increases from 0:00 to 9:00 compared with the data before the outbreak,
In addition, this paper further selects Jinhua City, a representative city in central Zhejiang Province, to explore the influence factors of ozone concentration before and after the outbreak, including meteorological and pollution factors. The results show that for meteorological factors, before and after the outbreak, ozone concentration is positively correlated with temperature but negatively correlated with relative humidity. After the outbreak, the correlation between ozone concentration and temperature decreased than before, while the correlation between ozone concentration and relative humidity increase slightly. For polluting gases, before and after the outbreak, the monthly trend of ozone concentration is negatively correlated with the concentrations of NO2, SO2, PM2.5, and PM10. After the outbreak, the concentrations of PM2.5, PM10, and ozone have been on an upward trend until March. the ozone concentration has increase compared with the data before outbreak, but SO2 and NO2 have decreased significantly. Therefore, when formulating the ozone control measures in Zhejiang Province, the control of the emission of pollution factors should be strengthened.

Date of Award	Jul 2022
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Jun He (Supervisor)