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Global ammonia emissions from synthetic nitrogen fertilizer applications in agricultural systems: Empirical and process‐based estimates and uncertainty
Author(s) -
Xu Rongting,
Tian Hanqin,
Pan Shufen,
Prior Stephen A.,
Feng Yucheng,
Batchelor William D.,
Chen Jian,
Yang Jia
Publication year - 2019
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14499
Subject(s) - cmaq , environmental science , context (archaeology) , fertilizer , air quality index , agriculture , greenhouse gas , climate change , atmospheric sciences , climatology , meteorology , agronomy , geography , ecology , archaeology , geology , biology
Excessive ammonia (NH 3 ) emitted from nitrogen (N) fertilizer applications in global croplands plays an important role in atmospheric aerosol production, resulting in visibility reduction and regional haze. However, large uncertainty exists in the estimates of NH 3 emissions from global and regional croplands, which utilize different data and methods. In this study, we have coupled a process‐based Dynamic Land Ecosystem Model (DLEM) with the bidirectional NH 3 exchange module in the Community Multiscale Air‐Quality (CMAQ) model (DLEM‐Bi‐NH 3 ) to quantify NH 3 emissions at the global and regional scale, and crop‐specific NH 3 emissions globally at a spatial resolution of 0.5° × 0.5° during 1961–2010. Results indicate that global NH 3 emissions from N fertilizer use have increased from 1.9 ± 0.03 to 16.7 ± 0.5 Tg N/year between 1961 and 2010. The annual increase of NH 3 emissions shows large spatial variations across the global land surface. Southern Asia, including China and India, has accounted for more than 50% of total global NH 3 emissions since the 1980s, followed by North America and Europe. Rice cultivation has been the largest contributor to total global NH 3 emissions since the 1990s, followed by corn and wheat. In addition, results show that empirical methods without considering environmental factors (constant emission factor in the IPCC Tier 1 guideline) could underestimate NH 3 emissions in context of climate change, with the highest difference (i.e., 6.9 Tg N/year) occurring in 2010. This study provides a robust estimate on global and regional NH 3 emissions over the past 50 years, which offers a reference for assessing air quality consequences of future nitrogen enrichment as well as nitrogen use efficiency improvement.