Ammonia Emissions May Be Substantially Underestimated in China

Area of Science:

• Atmospheric Chemistry and Air Pollution
• Environmental Science
• Geochemistry

Background:

• China is a major global source of atmospheric ammonia (NH3) emissions.
• High nitrogen (N) deposition levels in China are observed.
• Previous NH3 emission estimates were lower than deposition data suggested.

Purpose of the Study:

• To reevaluate NH3 emissions in China from 2000 to 2015.
• To reconcile emission estimates with observed N deposition and satellite data.
• To provide updated data for air pollution control strategies.

Main Methods:

• A mass balance approach was used for NH3 emission estimation.
• Nitrogen deposition monitoring data were utilized for validation.
• Satellite observations of NH3 concentrations were incorporated.

Main Results:

• Total NH3 emissions in China increased from 12.1 ± 0.8 Tg N yr-1 in 2000 to 15.6 ± 0.9 Tg N yr-1 in 2015.
• This represents an annual increase of 1.9%, approximately 40% higher than previous estimates.
• Underestimated NH3 emission rates from fertilizer and livestock were identified as key factors.

Conclusions:

• Revised NH3 emission estimates align with deposition and satellite measurements.
• Findings improve understanding of NH3 emissions in China.
• Future air quality strategies must address NH3 emission reduction potentials.