Agricultural Sector Homologous Emission Inventory of Air Pollutants and Greenhouse Gases for China

The agricultural sector is the largest source for air pollutants of ammonia (NH3) and greenhouse gases (GHGs) of nitrous oxide (N2O) and methane (CH4). Establishing a unified and homologous emission inventory of air pollutants and GHGs is essential for synergistic abatement pathway studies of air pollution and climate change. However, current agriculture emission inventories of air pollutants and GHGs are unclear due to the separated source classification and inconsistent calculating methodologies. This study adopted a synergistic approach to develop a unified emission inventory for NH3, N2O, and CH4 from the agricultural sector in China for 2021, based on crop and livestock types as the activity level data, and considered regional-specific species in emission factors. The results showed that China’s agricultural emissions in 2021 amounted to 7566.17 Gg of NH3, 486.14 Gg of N2O, and 14,979.71 Gg of CH4. Rice, cattle, and pigs were the primary contributors of NH3, N2O, and CH4. Hotspots of NH3 and N2O emissions were concentrated in the North China Plain and Sichuan Basin, whereas CH4 emissions were predominantly located in southern China. This study provides a crop- and livestock-specific data foundation for making region-specific and priority-based integrated strategies to improve air quality, mitigate climate change, and promote sustainable agricultural development in China.