A study led by Prof. WANG Tao, Executive Committee member of the Research Institute for Sustainable Urban Development (RISUD) and Chair Professor of Atmospheric Environment in the Department of Civil and Environmental Engineering, along with his research team, has unveiled the pivotal role of soil nitrous acid (HONO) emissions in the increase of the ozone mixing ratio in the air and the negative impact of these emissions on vegetation.
The team analysed global soil HONO emissions data from 1980 to 2016. They found that these emissions increased from 9.4 Tg N in 1980 to 11.5 Tg N in 2016. Using the chemistry-climate model to simulate the impact of soil HONO emissions on atmospheric composition, the researchers discovered an average 2.5% rise annually in the global surface ozone mixing ratio, with localised increases reaching 29%. The team pointed out that soil HONO emissions are influenced by the combined effects of nitrogen fertiliser usage and climate factors such as soil temperature and soil water content, resulting in seasonal and geographical variations.
The research established a comprehensive dataset by integrating multiple variables, incorporating climate factors like soil temperature, soil water content, and fertiliser type and application rates into the parameterisation scheme. For unquantifiable factors such as microbial activities, land use, and soil texture, the team applied diverse parameters based on latitude, longitude, and land use data for the corresponding soil samples.
The findings have been published in Nature Communications (https://www.nature.com/articles/s41467-025-57161-6).
