Characteristics of Temporal and Spatial Changes in Ozone and PM2.5 and Correlation Analysis in Heilongjiang Province

Abstract

The escalating ambient ozone (O3) pollution in China has garnered significant attention, necessitating an intensified focus on O3 pollution control and the coordinated management of PM2.5 and O3. This study reviews and analyzes the spatiotemporal characteristics of O3 and PM2.5 concentrations in 13 cities within Heilongjiang Province from 2019 to 2021. The analysis is based on data sourced from the ecological environment monitoring network. In addition to this, correlation analyses were executed to explore the interaction between the two pollutants. The findings reveal a declining trajectory in PM2.5 concentration over the past three years, while O3 concentration has exhibited an upward trend. Temporally, both O3 and PM2.5 concentrations display pronounced seasonal variations, with peaks evident during the spring and summer (May to July), as well as in the winter (January, February, and December). From a spatial standpoint, elevated O3 concentrations were identified in the southwestern cities of Harbin, Daqing, and Suihua, while the northwestern cities of Daxinganling and Heihe exhibited comparatively lower O3 concentrations, but the difference was not significant. Conversely, PM2.5 concentrations demonstrated substantial variation among the 13 cities (districts). Regarding their correlation, a noteworthy positive correlation between the two pollutants was observed in April and May, contrasted by a negative correlation in November and December. Weather categories such as excellent, good, lightly polluted, moderately polluted, and other weather showed a lower correlation, whereas heavily polluted and severely polluted categories demonstrated a stronger correlation. Furthermore, the correlation with severe pollution is greater than that with heavily polluted, further indicating that heavier air pollution is more conducive to the coexistence of O3 and PM2.5 to form composite pollution. On a provincial scale, the correlation between the two pollutants is progressively increasing annually. This signifies a closely intertwined and intricate interaction and transformation relationship between O3 and PM2.5, accentuating the urgency for synergistic control measures.