Satellite Support to Estimate Livestock Ammonia Emissions: A Case Study in Hebei, China

Abstract

Ammonia (NH3) is an important precursor of secondary inorganic aerosols that affect air quality and human health. Livestock production is an essential source of NH3 emissions, which exceeded half of the total NH3 emissions in China. However, our understanding of the livestock point NH3 emissions is still limited, due to the lack of both monitoring and statistical data. In this study, we established a satellite-based approach to estimating livestock point NH3 emissions by combining satellite observations and digital maps of points-of-interest (POI). Taking a case study in Hebei province over China, 1267 livestock points were identified. The point livestock NH3 emissions in 2020 ranged from 16.8 to 126.6 kg N ha−1 yr−1, with an average emission of 42.0 kg N ha−1 yr−1. The livestock NH3 emissions in Hebei showed an overall increasing trend, with a growth rate of 5.8% yr−1 between 2008 and 2020. In terms of seasonal changes, high livestock NH3 emissions mainly occurred in spring and summer, while low NH3 emissions were generally in autumn and winter. Satellite-derived point livestock NH3 emissions in Hebei were 2–4 times that of bottom-up NH3 emissions (EDGAR), suggesting that current used bottom-up emissions underestimated point livestock NH3 emissions. This study proposed a framework for the satellite-based estimation of livestock NH3 emissions, which is of great significance for relevant N management and NH3 emission reduction policy formulation.