A comprehensive ammonia emission inventory with high-resolution and its evaluation in the Beijing-Tianjin-Hebei (BTH) region, China

A comprehensive ammonia (NH3) emission inventory for the Beijing-Tianjin-Hebei (BTH) region was developed based on the updated source-specific emission factors (EFs) and the county-level activity data obtained from a full-coverage investigation launched in the BTH region for the first time. The NH3 emission inventory within 1 km x 1 km grid was generated using source-based spatial surrogates with geographical information system (GIS) technology. The total NH3 emission was 1573.7 Gg for the year ' 2010. The contributions from livestock, farmland, human, biomass burning, chemical industry, fuel combustion, waste disposal and on-road mobile source were approximately 56.6%, 28.6%, 7.2%, 3.4%, 1.1%, 1.3%, 1.0% and 0.8%, respectively. Among different cities, Shijiazhang, Handan, Xingtai, Tangshan and Cangzhou had higher NH3 emissions. Statistical analysis aiming at county-level emission of 180 counties in BTH indicated that the NH3 emission in most of the counties were less than 16 Gg. The maximum value of the county level emission was approximately 25.5 Gg. Higher NH3 emission was concentrated in the areas with more rural and agricultural activity. Monthly, higher NH3 emission occurred during the period from April to September, which could be attributed to the temperature and timing of planting practice. The validity of the estimated emissions were further evaluated from multiple perspectives covering (1) uncertainty analysis based on Monte Carlo simulation, (2) comparison with other studies, (3) quantitative analysis of improvement in spatial resolution of activity data, and (4) verification based on a comparison of the simulated and observed surface concentrations of ammonium. The detailed and validated ammonia emission inventory could provide valuable information for understanding air pollution formation mechanisms and help guide decision-making with respect to control strategies. (C) 2015 Elsevier Ltd. All rights reserved.