Abstract. China is one of the largest agricultural countries in the world. Thus,
NH3 emission from agricultural activities in China considerably affects
the country's regional air quality and visibility. In this study, a
high-resolution agricultural NH3 emission inventory compiled on 1 km × 1 km horizontal resolution was applied to calculate the NH3
mass burden in China and reliably estimate the influence of NH3 on
agriculture. The key parameter emission factors of this inventory were
enhanced by considering many experiment results, and the dynamic data of
spatial and temporal information were updated using statistical data of
2015. In addition to fertilizers and husbandry, farmland ecosystems,
livestock waste, crop residue burning, wood-based fuel combustion, and other
NH3 emission sources were included in this inventory. Furthermore, a
source apportionment tool, namely, the Integrated Source Apportionment Method
(ISAM) coupled with the air quality modeling system Regional Atmospheric
Modeling System and Community Multiscale Air Quality, was applied to capture
the contribution of NH3 emitted from total agriculture (Tagr) in China.
The aerosol mass concentration in 2015 was simulated, and results showed
that the high mass concentration of NH3 exceeded 10 µg m−3
and mainly appeared in the North China Plain, Central China, the Yangtze River
Delta, and the Sichuan Basin. Moreover, the annual average contribution of Tagr
NH3 to PM2.5 mass burden was 14 %–22 % in China. Specific to
the PM2.5 components, Tagr NH3 contributed dominantly to ammonium
formation (87.6 %) but trivially to sulfate formation (2.2 %). In
addition, several brute-force sensitivity tests were conducted to estimate the
impact of Tagr NH3 emission reduction on PM2.5 mass burden. In
contrast to the result of ISAM, even though the Tagr NH3 only provided
10.1 % contribution to nitrate under the current emission scenario, the
reduction of nitrate could reach 95.8 % upon removal of the Tagr NH3
emission. This deviation occurred because the contribution of NH3 to
nitrate should be small under a “rich NH3”environment and large under
a “poor NH3” environment. Thus, the influence of NH3 on nitrate
formation would be enhanced with the decrease in ambient NH3 mass
concentration.
High efficiency of livestock ammonia emission controls in alleviating particulate nitrate during a severe winter haze episode in northern China
