skip to main content

Search for: All records

Creators/Authors contains: "Chen, Zichong"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    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 NH3within the U.S. Corn Belt for the period April 2017 through December 2018. Hourly average NH3mixing ratios were measured at 100 and 56 m above the ground surface and fluxes were estimated using a modified gradient approach. The highest NH3mixing 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 NH3exchange was greatest in spring and fall with peak emissions of about +50 nmol m−2 s−l. Annual NH3emissions 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−1and +1,340 Gg NH3‐N y−1, respectively. Finally, considering the N2O budget over the same region, we estimatedmore »total reactive N emissions (i.e., N2O + NH3) of approximately 1,790 Gg N y−1from the U.S. Corn Belt, representing ~23% of the current annual new N input.

    « less