Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions

<p>Atmospheric ammonia (NH<span class="inline-formula"><sub>3</sub></span>) is a precursor to fine particulate matter and a source of nitrogen (N) deposition that can adversely affect ecosystem health. The main sources of NH<span class="inline-formula&...

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Main Authors: J. E. Hickman, N. Andela, E. Dammers, L. Clarisse, P.-F. Coheur, M. Van Damme, C. A. Di Vittorio, M. Ossohou, C. Galy-Lacaux​​​​​​​, K. Tsigaridis​​​​​​​, S. E. Bauer
Format: Article
Language:English
Published: Copernicus Publications 2021-11-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/21/16277/2021/acp-21-16277-2021.pdf
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author J. E. Hickman
N. Andela
N. Andela
E. Dammers
L. Clarisse
P.-F. Coheur
M. Van Damme
C. A. Di Vittorio
M. Ossohou
M. Ossohou
C. Galy-Lacaux​​​​​​​
K. Tsigaridis​​​​​​​
K. Tsigaridis​​​​​​​
S. E. Bauer
author_facet J. E. Hickman
N. Andela
N. Andela
E. Dammers
L. Clarisse
P.-F. Coheur
M. Van Damme
C. A. Di Vittorio
M. Ossohou
M. Ossohou
C. Galy-Lacaux​​​​​​​
K. Tsigaridis​​​​​​​
K. Tsigaridis​​​​​​​
S. E. Bauer
author_sort J. E. Hickman
collection DOAJ
description <p>Atmospheric ammonia (NH<span class="inline-formula"><sub>3</sub></span>) is a precursor to fine particulate matter and a source of nitrogen (N) deposition that can adversely affect ecosystem health. The main sources of NH<span class="inline-formula"><sub>3</sub></span> – agriculture and biomass burning – are undergoing are or expected to undergo substantial changes in Africa. Although evidence of increasing NH<span class="inline-formula"><sub>3</sub></span> over parts of Africa has been observed, the mechanisms behind these trends are not well understood. Here we use observations of atmospheric NH<span class="inline-formula"><sub>3</sub></span> vertical column densities (VCDs) from the Infrared Atmospheric Sounding Interferometer (IASI) along with other satellite observations of the land surface and atmosphere to evaluate how NH<span class="inline-formula"><sub>3</sub></span> concentrations have changed over Africa from 2008 through 2018, and what has caused those changes. In West Africa NH<span class="inline-formula"><sub>3</sub></span> VCDs are observed to increase during the late dry season, with increases of over 6 % yr<span class="inline-formula"><sup>−1</sup></span> in Nigeria during February and March (<span class="inline-formula"><i>p</i><i>&lt;</i>0.01</span>). These positive trends are associated with increasing burned area and CO trends during these months, likely related to agricultural preparation. Increases are also observed in the Lake Victoria basin region, where they are associated with expanding agricultural area. In contrast, NH<span class="inline-formula"><sub>3</sub></span> VCDs declined over the Sudd wetlands in South Sudan by over 1.5 % yr<span class="inline-formula"><sup>−1</sup></span>, though not significantly (<span class="inline-formula"><i>p</i>=0.28</span>). Annual maxima in NH<span class="inline-formula"><sub>3</sub></span> VCDs in South Sudan occur during February through May and are associated with the drying of temporarily flooded wetland soils, which favor emissions of NH<span class="inline-formula"><sub>3</sub></span>. The change in mean NH<span class="inline-formula"><sub>3</sub></span> VCDs over the Sudd is strongly correlated with variation in wetland extent in the Sudd: in years when more area remained flooded during the dry season, NH<span class="inline-formula"><sub>3</sub></span> VCDs were lower (<span class="inline-formula"><i>r</i>=0.64</span>, <span class="inline-formula"><i>p</i><i>&lt;</i>0.05</span>). Relationships between biomass burning and NH<span class="inline-formula"><sub>3</sub></span> may be observed when evaluating national-scale statistics: countries with the highest rates of increasing NH<span class="inline-formula"><sub>3</sub></span> VCDs also had high rates of growth in CO VCDs; burned area displayed a similar pattern, though not significantly. Livestock numbers were also higher in countries with intermediate or high rates of NH<span class="inline-formula"><sub>3</sub></span> VCD growth. Fertilizer use in Africa is currently low but growing; implementing practices that can limit NH<span class="inline-formula"><sub>3</sub></span> losses from fertilizer as agriculture is intensified may help mitigate impacts on health and ecosystems.</p>
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spelling doaj.art-ced0df0358b64428b48f897b744741f92022-12-21T19:53:18ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-11-0121162771629110.5194/acp-21-16277-2021Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regionsJ. E. Hickman0N. Andela1N. Andela2E. Dammers3L. Clarisse4P.-F. Coheur5M. Van Damme6C. A. Di Vittorio7M. Ossohou8M. Ossohou9C. Galy-Lacaux​​​​​​​10K. Tsigaridis​​​​​​​11K. Tsigaridis​​​​​​​12S. E. Bauer13NASA Goddard Institute for Space Studies, New York, USANASA Goddard Space Flight Center, Greenbelt, USAnow at: School of Earth and Environmental Sciences, Cardiff University, Cardiff, UKClimate Air and Sustainability, Netherlands Organisation for Applied Scientific Research (TNO), Utrecht, the NetherlandsAtmospheric Spectroscopy, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB),Brussels, BelgiumAtmospheric Spectroscopy, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB),Brussels, BelgiumAtmospheric Spectroscopy, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB),Brussels, BelgiumDepartment of Engineering, Wake Forest University, Winston-Salem, USALaboratoire des Sciences de la Matière, de l'Environnement et de l'Energie Solaire, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoirenow at: Sciences et Technologie, University of Man, Man, Côte d'IvoireLaboratoire d'Aérologie, Université Toulouse III Paul Sabatier / CNRS, Toulouse, FranceNASA Goddard Institute for Space Studies, New York, USACenter for Climate Systems Research, Columbia University, New York, USANASA Goddard Institute for Space Studies, New York, USA<p>Atmospheric ammonia (NH<span class="inline-formula"><sub>3</sub></span>) is a precursor to fine particulate matter and a source of nitrogen (N) deposition that can adversely affect ecosystem health. The main sources of NH<span class="inline-formula"><sub>3</sub></span> – agriculture and biomass burning – are undergoing are or expected to undergo substantial changes in Africa. Although evidence of increasing NH<span class="inline-formula"><sub>3</sub></span> over parts of Africa has been observed, the mechanisms behind these trends are not well understood. Here we use observations of atmospheric NH<span class="inline-formula"><sub>3</sub></span> vertical column densities (VCDs) from the Infrared Atmospheric Sounding Interferometer (IASI) along with other satellite observations of the land surface and atmosphere to evaluate how NH<span class="inline-formula"><sub>3</sub></span> concentrations have changed over Africa from 2008 through 2018, and what has caused those changes. In West Africa NH<span class="inline-formula"><sub>3</sub></span> VCDs are observed to increase during the late dry season, with increases of over 6 % yr<span class="inline-formula"><sup>−1</sup></span> in Nigeria during February and March (<span class="inline-formula"><i>p</i><i>&lt;</i>0.01</span>). These positive trends are associated with increasing burned area and CO trends during these months, likely related to agricultural preparation. Increases are also observed in the Lake Victoria basin region, where they are associated with expanding agricultural area. In contrast, NH<span class="inline-formula"><sub>3</sub></span> VCDs declined over the Sudd wetlands in South Sudan by over 1.5 % yr<span class="inline-formula"><sup>−1</sup></span>, though not significantly (<span class="inline-formula"><i>p</i>=0.28</span>). Annual maxima in NH<span class="inline-formula"><sub>3</sub></span> VCDs in South Sudan occur during February through May and are associated with the drying of temporarily flooded wetland soils, which favor emissions of NH<span class="inline-formula"><sub>3</sub></span>. The change in mean NH<span class="inline-formula"><sub>3</sub></span> VCDs over the Sudd is strongly correlated with variation in wetland extent in the Sudd: in years when more area remained flooded during the dry season, NH<span class="inline-formula"><sub>3</sub></span> VCDs were lower (<span class="inline-formula"><i>r</i>=0.64</span>, <span class="inline-formula"><i>p</i><i>&lt;</i>0.05</span>). Relationships between biomass burning and NH<span class="inline-formula"><sub>3</sub></span> may be observed when evaluating national-scale statistics: countries with the highest rates of increasing NH<span class="inline-formula"><sub>3</sub></span> VCDs also had high rates of growth in CO VCDs; burned area displayed a similar pattern, though not significantly. Livestock numbers were also higher in countries with intermediate or high rates of NH<span class="inline-formula"><sub>3</sub></span> VCD growth. Fertilizer use in Africa is currently low but growing; implementing practices that can limit NH<span class="inline-formula"><sub>3</sub></span> losses from fertilizer as agriculture is intensified may help mitigate impacts on health and ecosystems.</p>https://acp.copernicus.org/articles/21/16277/2021/acp-21-16277-2021.pdf
spellingShingle J. E. Hickman
N. Andela
N. Andela
E. Dammers
L. Clarisse
P.-F. Coheur
M. Van Damme
C. A. Di Vittorio
M. Ossohou
M. Ossohou
C. Galy-Lacaux​​​​​​​
K. Tsigaridis​​​​​​​
K. Tsigaridis​​​​​​​
S. E. Bauer
Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
Atmospheric Chemistry and Physics
title Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
title_full Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
title_fullStr Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
title_full_unstemmed Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
title_short Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH<sub>3</sub> trends in select African regions
title_sort changes in biomass burning wetland extent or agriculture drive atmospheric nh sub 3 sub trends in select african regions
url https://acp.copernicus.org/articles/21/16277/2021/acp-21-16277-2021.pdf
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