Tall Tower Ammonia Observations and Emission Estimates in the U.S. Midwest
Tall Tower Ammonia Observations and Emission Estimates in the U.S. Midwest
复制标题
DOI：
10.1029/2019jg005172
复制
发表时间：
2019-11
期刊：
影响因子：
--
通讯作者：
T. Griffis;Cheng Hu;John M. Baker;Jeffrey D. Wood;Dylan B. Millet;M. Erickson;Zhongjie Yu;M. J. Deventer;Cody Winker;Zichong Chen
中科院分区：
文献类型：
--
作者：
T. Griffis;Cheng Hu;John M. Baker;Jeffrey D. Wood;Dylan B. Millet;M. Erickson;Zhongjie Yu;M. J. Deventer;Cody Winker;Zichong Chen
由于合成氮（N）肥料的生产和集约化畜牧系统的扩散，大气氨（NH3）急剧增加。它是一种环境问题化学品，因为它很容易与大气酸反应产生细颗粒物，并间接导致一氧化二氮（N2 O）排放。在这里，我们介绍了2017年4月至2018年12月期间美国玉米带内NH3的第一个高塔观测结果。每小时平均NH3混合比测量在100和56米以上的地面和通量估计使用修改后的梯度方法。最高的NH3混合比（>30 nmol mol−1）出现在早春和晚秋，与该地区施肥的时间和暖空气温度的出现相一致。生态系统NH3净交换量在春季和秋季最大，峰值排放量约为+50 nmol m−2 s−l。使用最先进的清单估计的年NH3排放量范围为平均年总高塔通量的0.6至1.4倍（+2.1 nmol m−2 s−1）。如果高塔观测代表了上中西部和更广泛的美国玉米带地区，则年总排放量分别为+720 Gg NH3-N y−1和+1，340 Gg NH3-N y−1。最后，考虑到同一地区的N2 O预算，我们估计了总的活性氮排放量（即，N2 O + NH3）约为1，790 Gg N y−1，占当前年度新氮输入的23%。
Atmospheric ammonia (NH3) has increased dramatically as a consequence of the production of synthetic nitrogen (N) fertilizer and proliferation of intensive livestock systems. It is a chemical of environmental concern as it readily reacts with atmospheric acids to produce fine particulate matter and indirectly contributes to nitrous oxide (N2O) emissions. Here, we present the first tall tower observations of NH3 within the U.S. Corn Belt for the period April 2017 through December 2018. Hourly average NH3 mixing ratios were measured at 100 and 56 m above the ground surface and fluxes were estimated using a modified gradient approach. The highest NH3 mixing ratios (>30 nmol mol−1) occurred during early spring and late fall, coinciding with the timing of fertilizer application within the region and the occurrence of warm air temperatures. Net ecosystem NH3 exchange was greatest in spring and fall with peak emissions of about +50 nmol m−2 s−l. Annual NH3 emissions estimated using state‐of‐the‐art inventories ranged from 0.6 to 1.4 × the mean annual gross tall tower fluxes (+2.1 nmol m−2 s−1). If the tall tower observations are representative of the Upper Midwest and broader U.S. Corn Belt regions, the annual gross emissions were +720 Gg NH3‐N y−1 and +1,340 Gg NH3‐N y−1, respectively. Finally, considering the N2O budget over the same region, we estimated total reactive N emissions (i.e., N2O + NH3) of approximately 1,790 Gg N y−1 from the U.S. Corn Belt, representing ~23% of the current annual new N input.