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

Abstract

Livestock farming sector is an important anthropogenic emission source of ammonia (NH3 ) and greenhouse gases including nitrous oxide (N2 O) and methane (CH4 ). The NH3, not N2 O 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, N2 O 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, N2 O 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, N2 O 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, N2 O and CH4 in livestock farming. The livestock-derived NH3 emission explained approximately a quarter of the variations of atmospheric PM2.5 (size ≤2.5 μm) (24%) and PM10 (size ≤10 μm) (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 farming, especially pig and cattle breeding, should be paid more attention in the context of atmospheric particulate matter pollution and regional greenhouse gases management.