Managing ammonia emission for multi-benefits in China

Abstract Atmospheric ammonia (NH3) has multiple impacts on the environment, climate change and human health. China is the largest emitter of NH3 globally, with the dynamic inventory of NH3 emission remaining uncertain. Here, we use the high-resolution secondary national pollution survey, integrated satellite data, 15N isotope source apportionment and multiple models to better understand those key features of NH3 emissions and its impacts in China. Our results show that the total NH3 emissions were estimated to be 12.3 Tg yr-1 in 2017 with three emission peaks in April, June and October. NH3 emissions have contributed approximately 23% to secondary PM2.5 formation, a 19.7% increase in nitrogen loading of surface waters, while ammonium deposition led to a decrease in soil pH by 0.0035 units and an increase in the terrestrial carbon sink by 83.4 Tg C yr-1. Reducing NH3 emissions in China would contribute to the mitigation of air and water pollution challenges, saving damage costs estimated at around 22 billion US dollars due to avoided human and ecosystem health impacts.