Abstract
Reduced nitrogen (N) is central to global biogeochemistry, yet there are large uncertainties surrounding its sources and rate of cycling. Here, we present observations of gas-phase urea (CO(NH2)2) in the atmosphere from airborne high-resolution mass spectrometer measurements over the North Atlantic Ocean. We show that urea is ubiquitous in the lower troposphere in the summer, autumn, and winter but was not detected in the spring. The observations suggest that the ocean is the primary emission source, but further studies are required to understand the responsible mechanisms. Urea is also observed aloft due to long-range transport of biomass-burning plumes. These observations alongside global model simulations point to urea being an important, and currently unaccounted for, component of reduced-N to the remote marine atmosphere. Airborne transfer of urea between nutrient-rich and -poor parts of the ocean can occur readily and could impact ecosystems and oceanic uptake of carbon dioxide, with potentially important climate implications.
| Original language | English |
|---|---|
| Article number | e2218127120 |
| Pages (from-to) | e2218127120 |
| Number of pages | 7 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 120 |
| Issue number | 25 |
| DOIs | |
| Publication status | Published - 14 Jun 2023 |
Bibliographical note
Funding Information:We gratefully acknowledge the financial support provided by the UK Natural Environment Research Council (NERC) [grant nos. NE/N016238/1 (MOYA), NE/S000518/1 (ARNA), NE/S004467/1 (ACRUISE)] and especially for the extensive data provided by the North Atlantic Climate System Integrated Study. M.A.H.K. and D.E.S. were supported by NERC (NE/ K004905/1), the Primary Science Teaching Trust, and Bristol ChemLabS. E.M., A.M., and P.B. thank the NERC Earth, Atmosphere and Ocean Doctoral Training Program for PhD studentships (NERC grant reference: NE/L002469/1). E.M. would also like to thank the British Antarctic Survey for their partnership. Airborne data were obtained using the BAe-146-301 Atmospheric Research Aircraft flown by Airtask Ltd and managed by FAAM Airborne Laboratory, jointly operated by UK Research and Innovation and the University of Leeds. We would like to give special thanks to the Airtask pilots and engineers and all staff at FAAM Airborne Laboratory for their hard work in helping plan and execute successful flight campaigns across the different projects. We acknowledge the use of MODIS near-surface chlorophyll-a concentration data (https:// oceancolor.gsfc.nasa.gov/data/10.5067/AQUA/MODIS/L3M/CHL/2022/[oceancolor.gsfc.nasa.gov]). We would like to thank Joel Thornton and Felipe Lopez-Hilfiker for their helpful discussions on the ToF-CIMS ion molecule reaction region design.
Funding Information:
ACKNOWLEDGMENTS. We gratefully acknowledge the financial support provided by the UK Natural Environment Research Council (NERC) [grant nos. NE/N016238/1 (MOYA), NE/S000518/1 (ARNA), NE/S004467/1 (ACRUISE)] and especially for the extensive data provided by the North Atlantic Climate System Integrated Study. M.A.H.K. and D.E.S. were supported by NERC (NE/ K004905/1), the Primary Science Teaching Trust, and Bristol ChemLabS. E.M., A.M., and P.B. thank the NERC Earth, Atmosphere and Ocean Doctoral Training Program for PhD studentships (NERC grant reference: NE/L002469/1). E.M. would also like to thank the British Antarctic Survey for their partnership. Airborne data were obtained using the BAe-146-301 Atmospheric Research Aircraft flown by Airtask Ltd and managed by FAAM Airborne Laboratory, jointly operated by UK Research and Innovation and the University of Leeds. We would like to give special thanks to the Airtask pilots and engineers and all staff at FAAM Airborne Laboratory for their hard work in helping plan and execute successful flight campaigns across the different projects.We acknowledge the use of MODIS near-surface chlorophyll-a concentration data (https:// oceancolor.gsfc.nasa.gov/data/10.5067/AQUA/MODIS/L3M/CHL/2022/ [oceancolor.gsfc.nasa.gov]). We would like to thank Joel Thornton and Felipe Lopez-Hilfiker for their helpful discussions on the ToF-CIMS ion molecule reaction region design.
Publisher Copyright:
© 2023 the Author(s).
