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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #378974

Research Project: Increasing the Productivity and Resilience to Climate Variability of Agricultural Production Systems in the Upper Midwest U.S. while Reducing Negative Impact on the Environment

Location: Soil and Water Management Research

Title: A multiyear constraint on ammonia emissions and deposition within the US Corn Belt

item HU, CHENG - Nanjing Forestry University
item GRIFFIS, TIMOTHY - University Of Minnesota
item FRIE, ALEXANDER - University Of Minnesota
item Baker, John
item WOOD, JEFFREY - University Of Missouri
item MILLET, DYLAN - University Of Minnesota
item YU, ZHONGJIE - University Of Minnesota
item YU, XUEYING - University Of Minnesota
item CZARNETZKI, ALAN - University Of Northern Iowa

Submitted to: Geophysical Research Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2021
Publication Date: 2/6/2021
Citation: Hu, C., Griffis, T., Frie, A., Baker, J.M., Wood, J.D., Millet, D.B., Yu, Z., Yu, X., Czarnetzki, A.C. 2021. A multiyear constraint on ammonia emissions and deposition within the US Corn Belt. Geophysical Research Letters. 48(6). Article e2020GL090865.

Interpretive Summary: Ammonia (NH3) is an atmospheric pollutant that negatively afects human health, and agricultural activities are the primary source. Historically, it has been difficult to measure and thus challenging to pinpoint sources and develop mitigation strategies. We used continous NH3 concentration measurements made from the top of a 100 m radio tower in conjunction with bi-weekly ground observations from the Ammonia Monitoring Network and an atmospheric chemistry model to compare against the estimates of the U.S. National Emissions Inventory over 3 growing seasons, 2017-2019. Our results showed that emissions peak in the April-June time period, and are substantially higher, by a factor of 1.6-1.7, than the NEI estimates. Averaged over the growing season, results were surprisingly consistent across years, ranging from 3.27 to 3.64 nmol m-2,s-1, although within each year there was substantial variability due to weather and land management. We also found that re-deposition of NH3 was approximaately 40% of emissions on agricultural lands, and over 100% of emissions on natural lands. These results can serve as a benchmark for evaluating the effectiveness of future mitigation efforts.

Technical Abstract: The US Corn Belt is a global hotspot of atmospheric ammonia (NH3), a gas known to adversely impact the environment and human health. We combine hourly tall tower (100 m) measurements and bi-weekly, spatially distributed, ground-based observations from the Ammonia Monitoring Network with the U.S. National Emissions Inventory (NEI) and WRF-Chem simulations to constrain NH3 emissions from April- September, 2017-2019. We show that: (1) NH3 emissions peaked from May to June and were 1.6 to 1.7 times higher than NEI emissions estimates; (2) average growing season NH3 emissions from agricultural lands were remarkably similar across years (3.27 to 3.64 nmol m-2 s-1), yet showed substantial episodic variability driven by meteorology and land management; (3) dry deposition was 40% of gross emissions from agricultural lands and exceeded 100% of gross emissions in natural lands. Our findings provide an important benchmark for evaluating future NH3 emissions and mitigation efforts.