Managing Ammonia for Multiple Benefits Based on Verified High-Resolution Emission Inventory in China

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Agricultural Science

Background:

• Atmospheric ammonia (NH3) significantly impacts environment, climate, and health.
• China is the world's largest NH3 emitter, but emission data is uncertain.

Purpose of the Study:

• To quantify NH3 emissions in China for 2020.
• To assess the environmental impacts of NH3 emissions.
• To identify key drivers of NH3 emissions.

Main Methods:

• Utilized national agricultural pollution source censuses.
• Integrated satellite data and 15N isotope source apportionment.
• Employed multiple atmospheric and ecosystem models.

Main Results:

• Estimated total NH3 emissions at 11.2 ± 1.1 million tonnes in 2020.
• Identified peak emissions in April, June, and October, driven by agriculture (74%).
• Quantified NH3 contribution to secondary PM2.5 (22%), nitrogen loading (16.6%), soil acidification, and carbon sequestration.

Conclusions:

• Agricultural NH3 emissions are a major environmental concern in China.
• Reducing NH3 emissions can mitigate air and water pollution.
• Mitigation efforts offer significant economic benefits through avoided health and ecosystem damages.