Spatio-Temporal Emissions of Ammonia and Greenhouse Gases from Livestock and Its Relation to Atmospheric Particulate Matter Pollution in the Beijing-Tianjin-Hebei Region

Livestock farming sector is an important anthropogenic emission source of ammonia (NH3) and greenhouse gases including nitrous oxide (N2O) and methane (CH4). The NH3 , not N2O and CH4 , is known as an important gaseous precursor to cause atmospheric particulate matter (PM) pollution. However, the relationship between livestock-derived NH3 and atmospheric PM pollution has not been sufficiently investigated, especially in the developed regions with serious air pollution. Here, we studied the spatio-temporal emissions of NH3, N2O and CH4 from livestock farming as well as the relationship between livestock NH3 emission and atmospheric PM pollution in the Beijing-Tianjin-Hebei Region, one of the most developed and air polluted area in China. Over the past 40 years, livestock-derived emissions of NH3, N2O and CH4 had experienced four temporal stages (1978-1990: low level; 1991-1995: rapid growth; 1996-2005: reached hot moments; 2006-2018: stable at a high level). Livestock-derived emissions of NH3, N2O and CH4 were 813, 19 and 499 Gg in 2017, respectively. The southeastern plain was the hotspot, and the pig and cattle were the main sources (78-99%) of NH3, N2O and CH4 in livestock fanning. The livestock-derived NH3 emission explained approximately a quarter of the variations of atmospheric PM2.5 (size <= 2.5 mu m) (24%) and PM10 (size <= 10 gm) (22%) pollution. Based on the knowledge of atmospheric chemical processes, we concluded that the livestock-derived NH3 emission significantly affected atmospheric PM2.5 and PM10, pollution in the Beijing-Tianjin-Hebei Region. Consequently, the livestock fanning, especially pig and cattle breeding, should be paid more attention in the context of atmospheric particulate matter pollution and regional greenhouse gases management.