Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa
Abstract Light-absorbing aerosols, particularly black carbon (BC), have significant impacts on human health and the climate. They are also the least-studied fraction of atmospheric particles, particularly in residential areas of southern Africa. The optical characteristics of ground-based light-abso...
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| Format: | Article |
| Language: | English |
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Springer
2024-12-01
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| Series: | Aerosol and Air Quality Research |
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| Online Access: | https://doi.org/10.4209/aaqr.2019.09.0443 |
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| author | Nopasika A. Xulu Stuart J. Piketh Gregor T. Feig Daniel A. Lack Rebecca M. Garland |
| author_facet | Nopasika A. Xulu Stuart J. Piketh Gregor T. Feig Daniel A. Lack Rebecca M. Garland |
| author_sort | Nopasika A. Xulu |
| collection | DOAJ |
| description | Abstract Light-absorbing aerosols, particularly black carbon (BC), have significant impacts on human health and the climate. They are also the least-studied fraction of atmospheric particles, particularly in residential areas of southern Africa. The optical characteristics of ground-based light-absorbing aerosols from Kwadela Township in South Africa are investigated in this study. Daily averaged ambient PM25 highest levels were 51.39 µg m–3 and 32.18 µg m–3, whereas hourly averages peaked at 61.31 µg m–3 and 34.69 µg m–3 during winter and summer, respectively. Levels of daily averaged light-absorbing aerosols were 2.9 times higher (1.89 ± 0.5 µg m–3) in winter 2014 than in summer 2015 (0.66 ± 0.2 µg m–3). In both seasons, hourly averaged levels showed bimodal diurnal cycles, which correlated with the PM2.5 diurnal patterns that indicated distinct peaks in the morning and evening. These diurnal cycle peak periods corresponded with the times of increased solid domestic fuel usage, road traffic, and also shallower boundary layer. On average, light-absorbing aerosols contributed a larger proportion of total ambient PM2.5 levels in winter (6.5 ± 1.0%) than in summer (3.4 ± 1.0%). The winter average Absorption Ångstrӧm exponent AAE(370/880 nm) (1.7± 0.5), indicated the dominance of brown carbon (BrC) from biofuel/biomass burning and/or low-quality coal combustion emissions. In summer, the average AAE(370/950 nm) (1.3 ± 0.7), suggested the presence of BC and BrC in the mornings and evenings possibly from fossil fuel combustion sources. At midday and at night in summer, the AAE was close to 1, suggesting more BC contributions from sources such as diesel emissions during this time. A combination of BC and BrC particulates dominated on 50% and 5% of the summer days, respectively, whereas fresh BC were only measured in summer days (23%). Residential solid-fuel and/biomass combustion are important sources of light-absorbing aerosols in this study region, with concomitant human health and environmental impacts. |
| format | Article |
| id | doaj-art-308f343ff6c74d9294c6581267efc771 |
| institution | Kabale University |
| issn | 1680-8584 2071-1409 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Springer |
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| series | Aerosol and Air Quality Research |
| spelling | doaj-art-308f343ff6c74d9294c6581267efc7712025-02-09T12:19:20ZengSpringerAerosol and Air Quality Research1680-85842071-14092024-12-012081812183210.4209/aaqr.2019.09.0443Characterizing Light-absorbing Aerosols in a Low-income Settlement in South AfricaNopasika A. Xulu0Stuart J. Piketh1Gregor T. Feig2Daniel A. Lack3Rebecca M. Garland4Unit for Environmental Sciences and Management, North-West UniversityUnit for Environmental Sciences and Management, North-West UniversitySouth African Weather Service, South African Air Quality Information (SAAQIS)Daniel A Lack, Transport Emissions, Air Quality and ClimateUnit for Environmental Sciences and Management, North-West UniversityAbstract Light-absorbing aerosols, particularly black carbon (BC), have significant impacts on human health and the climate. They are also the least-studied fraction of atmospheric particles, particularly in residential areas of southern Africa. The optical characteristics of ground-based light-absorbing aerosols from Kwadela Township in South Africa are investigated in this study. Daily averaged ambient PM25 highest levels were 51.39 µg m–3 and 32.18 µg m–3, whereas hourly averages peaked at 61.31 µg m–3 and 34.69 µg m–3 during winter and summer, respectively. Levels of daily averaged light-absorbing aerosols were 2.9 times higher (1.89 ± 0.5 µg m–3) in winter 2014 than in summer 2015 (0.66 ± 0.2 µg m–3). In both seasons, hourly averaged levels showed bimodal diurnal cycles, which correlated with the PM2.5 diurnal patterns that indicated distinct peaks in the morning and evening. These diurnal cycle peak periods corresponded with the times of increased solid domestic fuel usage, road traffic, and also shallower boundary layer. On average, light-absorbing aerosols contributed a larger proportion of total ambient PM2.5 levels in winter (6.5 ± 1.0%) than in summer (3.4 ± 1.0%). The winter average Absorption Ångstrӧm exponent AAE(370/880 nm) (1.7± 0.5), indicated the dominance of brown carbon (BrC) from biofuel/biomass burning and/or low-quality coal combustion emissions. In summer, the average AAE(370/950 nm) (1.3 ± 0.7), suggested the presence of BC and BrC in the mornings and evenings possibly from fossil fuel combustion sources. At midday and at night in summer, the AAE was close to 1, suggesting more BC contributions from sources such as diesel emissions during this time. A combination of BC and BrC particulates dominated on 50% and 5% of the summer days, respectively, whereas fresh BC were only measured in summer days (23%). Residential solid-fuel and/biomass combustion are important sources of light-absorbing aerosols in this study region, with concomitant human health and environmental impacts.https://doi.org/10.4209/aaqr.2019.09.0443Light-absorbing aerosolsAbsorption Ångstrӧm exponentResidential solid-fuel combustionAethalometerMpumalangaSouth Africa |
| spellingShingle | Nopasika A. Xulu Stuart J. Piketh Gregor T. Feig Daniel A. Lack Rebecca M. Garland Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa Aerosol and Air Quality Research Light-absorbing aerosols Absorption Ångstrӧm exponent Residential solid-fuel combustion Aethalometer Mpumalanga South Africa |
| title | Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa |
| title_full | Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa |
| title_fullStr | Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa |
| title_full_unstemmed | Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa |
| title_short | Characterizing Light-absorbing Aerosols in a Low-income Settlement in South Africa |
| title_sort | characterizing light absorbing aerosols in a low income settlement in south africa |
| topic | Light-absorbing aerosols Absorption Ångstrӧm exponent Residential solid-fuel combustion Aethalometer Mpumalanga South Africa |
| url | https://doi.org/10.4209/aaqr.2019.09.0443 |
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