Impact of Black Carbon on Surface Ozone in the Yangtze River Delta from 2015 to 2018

Abstract

Despite the yearly decline in PM2.5 in China, surface ozone has been rapidly increasing recently, which makes it imperative to coordinate and control both PM2.5 and ozone in the atmosphere. This study utilized the data of pollutant concentrations and meteorological elements during 2015 to 2018 in Nanjing, China to analyze the daily correlation between black carbon and ozone (CBO), and the distribution of the pollutant concentrations under different levels of CBO. Besides, the diurnal variations of pollutant concentrations and meteorological elements under high positive and negative CBO were discussed and compared. The results show that the percentage of positive CBO had been increasing at the average rate of 7.1%/year, and it was 38.7% in summer on average, nearly twice of that in other seasons (19.2%). The average black carbon (BC), PM2.5 and NO2 under positive CBO was lower than those under negative CBO. It is noticeable that the surface ozone began to ascend when CBO was up to 0.2, with PM2.5 and NO2 decreasing and BC remaining steady. Under negative CBO, pollutant concentrations and meteorological elements showed obvious diurnal variations: BC showed a double-peak pattern and surface ozone, PM2.5, SO2 and CO showed single-peak patterns and NO2 showed a trough from 10:00 to 19:00. Wind speed and visibility showed a single-peak pattern with little seasonal difference. Relative humidity rose first, then it lowered and then it rose. Under positive CBO, the patterns of diurnal variations became less obvious, and some of them even showed no patterns, but just fluctuated at a certain level.

Some Features of Black Carbon Aerosols Connected with Regional Climate Over Pristine Environment

“…The following plots (Figure 12) depict the regression analysis of BC aerosols and ozone during December, January, and February 2022. A negative association between BC aerosols and surface ozone was observed, with correlation coefficient values of -0.53 for December, -0.23 for January, and -0.39 for February, which matched with other studies [71,72] . These two parameters show opposite characteristics, e.g., BC peaks during the morning and early night hours and plummets during the afternoon (diurnal variations) while ozone peaks during the afternoon (high temperature).…”

Analysis of Air Quality Change Characteristics and Correlation with Meteorological Factors in Yangtze River Delta City Cluster

“…In terms of its variation, the areas with high and higher AQI values were more widely distributed in winter, followed by spring, and the areas with low and lower AQI values were dominant in autumn. It can be inferred that the northwest was the key area for air pollution prevention and control in the Yangtze River Delta city cluster, and winter was the key time point for prevention and control [29][30][31][32][33][34][35][36][37].…”