Influence of Urban-Road Green Space Plant Configurations on NO2 Concentrations in Nanjing City during Winter

Abstract

The rapid urbanization and growing number of motor vehicles in China have led to a significant increase in NO2 emissions, posing a severe threat to the air quality in cities. Road traffic pollution has emerged as a significant environmental issue in China. Exploring the utilization of landscape plants for air pollutant mitigation and assessing the influence of various plant concentrations on reducing air pollution holds great significance in urban ecological environment protection and urban development. Through field surveys and data collection in January 2022, the objectives of this study are to explore the relationship between road meteorological factors and the reduction in air pollutant concentrations in Nanjing city’s road green spaces and to investigate the influence of plant configuration in road green spaces on pollutant concentration. The findings demonstrate a distinct positive correlation between road traffic volume during winter peak hours and the concentration of NO2 pollution gas. Furthermore, meteorological factors, including temperature and light intensity, strongly correlate with air pollutant concentrations. Open green spaces with ventilated structures and high tree planting density (deciduous trees are preferred) exhibit optimal purification effects. Excessive or insufficient planting density hinders the purifying function of green belts. In conclusion, our research on plant configurations and air pollutant concentrations in Nanjing City during the winter suggests that the recommended road green space plant configuration in Nanjing is a combination of arbor (deciduous tree), shrub, and grass.