Atmospheric Black Carbon Loadings and Sources over Eastern Sub-Saharan Africa Are Governed by the Regional Savanna Fires
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acs.est.2c05837.pdf
Description
Published version
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5.23 MB
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Checksum (MD5)
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Author(s)
Kirago, Leonard
Gustafsson, Örjan
Gaita, Samuel M
Haslett, Sophie L
deWitt, H Langley
Gasore, Jimmy
Potter, Katherine E
Prinn, Ronald G
Rupakheti, Maheswar
Ndikubwimana, Jean de Dieu
Date Issued
2022
Journal
Environmental Science and Technology
Publisher
American Chemical Society (ACS)
Citation
Kirago, Leonard, Gustafsson, Örjan, Gaita, Samuel M, Haslett, Sophie L, deWitt, H Langley et al. 2022. "Atmospheric Black Carbon Loadings and Sources over Eastern Sub-Saharan Africa Are Governed by the Regional Savanna Fires." Environmental Science and Technology, 56 (22).
Version
Final published version
Abstract
Vast black carbon (BC) emissions from sub-Saharan Africa are perceived to warm the regional climate, impact rainfall patterns, and impair human respiratory health. However, the magnitudes of these perturbations are ill-constrained, largely due to limited ground-based observations and uncertainties in emissions from different sources. This paper reports multiyear concentrations of BC and other key PM2.5 aerosol constituents from the Rwanda Climate Observatory, serving as a regional receptor site. We find a strong seasonal cycle for all investigated chemical species, where the maxima coincide with large-scale upwind savanna fires. BC concentrations show notable interannual variability, with no clear long-term trend. The Δ14C and δ13C signatures of BC unambiguously show highly elevated biomass burning contributions, up to 93 ± 3%, with a clear and strong savanna burning imprint. We further observe a near-equal contribution from C3 and C4 plants, irrespective of air mass source region or season. In addition, the study provides improved relative emission factors of key aerosol components, organic carbon (OC), K+, and NO3-, in savanna-fires-influenced background atmosphere. Altogether, we report quantitative source constraints on Eastern Africa BC emissions, with implications for parameterization of satellite fire and bottom-up emission inventories as well as regional climate and chemical transport modeling.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1021/ACS.EST.2C05837
