Ozone pollution is a global environmental concern that not only threatens human health and crop production, but also worsens global warming.
Ozone pollution is a global environmental concern that not only threatens human health and crop production, but also worsens global warming. While the formation of ozone is often attributed to anthropogenic pollutants, soil emissions are revealed to be another important source. The Hong Kong Polytechnic University (PolyU) researchers have examined global soil nitrous acid (HONO) emissions data from 1980 to 2016 and incorporated them in a chemistry-climate model to unveil the pivotal role soil HONO emissions play in the increase of the ozone mixing ratio in air and its negative impact on vegetation.
Soil microbial activities and agricultural practices, notably fertiliser application, release various gases from soil into the atmosphere. Previous studies found that soil HONO emissions contribute up to 80% of the atmospheric HONO mixing ratio. The interaction of HONO with other pollutants in the atmosphere is crucial to the chemical production of ozone. HONO also promotes ozone formation by elevating concentrations of its precursors nitrogen oxide (NOₓ).
Prof. Tao Wang, Chair Professor of Atmospheric Environment of the PolyU Department of Civil and Environmental Engineering, along with his research team, has compiled a dataset of soil HONO emission measurements from diverse ecosystems worldwide and pioneered a quantitative parameterisation scheme to quantify the impact brought by the emissions. The research made possible the comprehensive dataset measurements by integrating multiple variables, including climate factors like soil temperature and soil water content, and fertiliser type and application rates into the scheme. For unquantifiable factors such as microbial activities, land use and soil texture, the team applied diverse parameterisations based on latitude, longitude and land use data of the corresponding soil samples. The findings have been published in Nature Communications, with Dr Yanan WANG, PolyU Postdoctoral Fellow, and Dr Qinyi LI, Professor at Shandong University, being the co-first authors.
Read more at The Hong Kong Polytechnic University
Image: PolyU research reveals rising soil nitrous acid emissions driven by climate change and fertilisation accelerate global ozone pollution. (Credit: © 2025 Research and Innovation Office, The Hong Kong Polytechnic University. All Rights Reserved.)
