Find in Library

<p>China is one of the largest agricultural countries in the world. Thus, <span class="inline-formula">NH₃</span> emission from agricultural activities in China considerably affects the country's regional air quality and visibility. In this study, a high-resolution agricultural <span class="inline-formula">NH₃</span> emission inventory compiled on 1&thinsp;km&thinsp;<span class="inline-formula">×</span>&thinsp;1&thinsp;km horizontal resolution was applied to calculate the <span class="inline-formula">NH₃</span> mass burden in China and reliably estimate the influence of <span class="inline-formula">NH₃</span> on agriculture. The key parameter emission factors of this inventory were enhanced by considering many experiment results, and the dynamic data of spatial and temporal information were updated using statistical data of 2015. In addition to fertilizers and husbandry, farmland ecosystems, livestock waste, crop residue burning, wood-based fuel combustion, and other <span class="inline-formula">NH₃</span> emission sources were included in this inventory. Furthermore, a source apportionment tool, namely, the Integrated Source Apportionment Method (ISAM) coupled with the air quality modeling system Regional Atmospheric Modeling System and Community Multiscale Air Quality, was applied to capture the contribution of <span class="inline-formula">NH₃</span> emitted from total agriculture (<span class="inline-formula"><i>T</i>_agr</span>) in China. The aerosol mass concentration in 2015 was simulated, and results showed that the high mass concentration of <span class="inline-formula">NH₃</span> exceeded 10&thinsp;<span class="inline-formula">µ</span>g&thinsp;m<span class="inline-formula">⁻³</span> and mainly appeared in the North China Plain, Central China, the Yangtze River Delta, and the Sichuan Basin. Moreover, the annual average contribution of <span class="inline-formula"><i>T</i>_agr</span> <span class="inline-formula">NH₃</span> to PM<span class="inline-formula">_2.5</span> mass burden was 14&thinsp;%–22&thinsp;% in China. Specific to the PM<span class="inline-formula">_2.5</span> components, <span class="inline-formula"><i>T</i>_agr</span> <span class="inline-formula">NH₃</span> contributed dominantly to ammonium formation (87.6&thinsp;%) but trivially to sulfate formation (2.2&thinsp;%). In addition, several brute-force sensitivity tests were conducted to estimate the impact of <span class="inline-formula"><i>T</i>_agr</span> <span class="inline-formula">NH₃</span> emission reduction on PM<span class="inline-formula">_2.5</span> mass burden. In contrast to the result of ISAM, even though the <span class="inline-formula"><i>T</i>_agr</span> <span class="inline-formula">NH₃</span> only provided 10.1&thinsp;% contribution to nitrate under the current emission scenario, the reduction of nitrate could reach 95.8&thinsp;% upon removal of the <span class="inline-formula"><i>T</i>_agr</span> <span class="inline-formula">NH₃</span> emission. This deviation occurred because the contribution of <span class="inline-formula">NH₃</span> to nitrate should be small under a “rich <span class="inline-formula">NH₃</span>”environment and large under a “poor <span class="inline-formula">NH₃</span>” environment. Thus, the influence of <span class="inline-formula">NH₃</span> on nitrate formation would be enhanced with the decrease in ambient <span class="inline-formula">NH₃</span> mass concentration.</p>