Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan

Atmospheric aerosol samples of PM<sub>2.5</sub> and PM<sub>10</sub> were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contribu...

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Main Authors: S. L. Mkoma, K. Kawamura, P. Q. Fu
Format: Article
Language:English
Published: Copernicus Publications 2013-10-01
Series:Atmospheric Chemistry and Physics
Online Access:http://www.atmos-chem-phys.net/13/10325/2013/acp-13-10325-2013.pdf
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spelling doaj-364b364fa1df4455923b6f3bd47ae5ba2020-11-25T00:40:36ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242013-10-011320103251033810.5194/acp-13-10325-2013Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosanS. L. MkomaK. KawamuraP. Q. FuAtmospheric aerosol samples of PM<sub>2.5</sub> and PM<sub>10</sub> were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC) and particulate matter (PM) mass were estimated to be 46&ndash;52% and 87&ndash;13%, respectively. The mean mass concentrations of PM<sub>2.5</sub> and PM<sub>10</sub> were 28 ± 6 μg m<sup>−3</sup> and 47 ± 8 μg m<sup>−3</sup> in wet season, and 39 ± 10 μg m<sup>−3</sup> and 61 ± 19 μg m<sup>−3</sup> in dry season, respectively. Total carbon (TC) accounted for 16&ndash;19% of the PM<sub>2.5</sub> mass and 13&ndash;15% of the PM<sub>10</sub> mass. On average, 86 to 89% of TC in PM<sub>2.5</sub> and 87 to 90% of TC in PM<sub>10</sub> was OC, of which 67&ndash;72% and 63% was found to be water-soluble organic carbon (WSOC) in PM<sub>2.5</sub> and PM<sub>10</sub>, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose) well correlated with non-sea-salt potassium (nss-K<sup>+</sup>) (<i>r</i><sup>2</sup> = 0.56&ndash;0.75), OC (<i>r</i><sup>2</sup> = 0.75&ndash;0.96) and WSOC (<i>r</i><sup>2</sup> = 0.52&ndash;0.78). The K<sup>+</sup> / OC ratios varied from 0.06 to 0.36 in PM<sub>2.5</sub> and from 0.03 to 0.36 in PM<sub>10</sub> with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3&ndash;4% for PM<sub>2.5</sub> and PM<sub>10</sub> in both seasons. We found lower levoglucosan / K<sup>+</sup> ratios and higher K<sup>+</sup> / EC (elemental carbon) ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K<sup>+</sup> is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely influence the air quality in Tanzania.http://www.atmos-chem-phys.net/13/10325/2013/acp-13-10325-2013.pdf
collection DOAJ
language English
format Article
sources DOAJ
author S. L. Mkoma
K. Kawamura
P. Q. Fu
spellingShingle S. L. Mkoma
K. Kawamura
P. Q. Fu
Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
Atmospheric Chemistry and Physics
author_facet S. L. Mkoma
K. Kawamura
P. Q. Fu
author_sort S. L. Mkoma
title Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
title_short Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
title_full Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
title_fullStr Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
title_full_unstemmed Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
title_sort contributions of biomass/biofuel burning to organic aerosols and particulate matter in tanzania, east africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan
publisher Copernicus Publications
series Atmospheric Chemistry and Physics
issn 1680-7316
1680-7324
publishDate 2013-10-01
description Atmospheric aerosol samples of PM<sub>2.5</sub> and PM<sub>10</sub> were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC) and particulate matter (PM) mass were estimated to be 46&ndash;52% and 87&ndash;13%, respectively. The mean mass concentrations of PM<sub>2.5</sub> and PM<sub>10</sub> were 28 ± 6 μg m<sup>−3</sup> and 47 ± 8 μg m<sup>−3</sup> in wet season, and 39 ± 10 μg m<sup>−3</sup> and 61 ± 19 μg m<sup>−3</sup> in dry season, respectively. Total carbon (TC) accounted for 16&ndash;19% of the PM<sub>2.5</sub> mass and 13&ndash;15% of the PM<sub>10</sub> mass. On average, 86 to 89% of TC in PM<sub>2.5</sub> and 87 to 90% of TC in PM<sub>10</sub> was OC, of which 67&ndash;72% and 63% was found to be water-soluble organic carbon (WSOC) in PM<sub>2.5</sub> and PM<sub>10</sub>, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose) well correlated with non-sea-salt potassium (nss-K<sup>+</sup>) (<i>r</i><sup>2</sup> = 0.56&ndash;0.75), OC (<i>r</i><sup>2</sup> = 0.75&ndash;0.96) and WSOC (<i>r</i><sup>2</sup> = 0.52&ndash;0.78). The K<sup>+</sup> / OC ratios varied from 0.06 to 0.36 in PM<sub>2.5</sub> and from 0.03 to 0.36 in PM<sub>10</sub> with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3&ndash;4% for PM<sub>2.5</sub> and PM<sub>10</sub> in both seasons. We found lower levoglucosan / K<sup>+</sup> ratios and higher K<sup>+</sup> / EC (elemental carbon) ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K<sup>+</sup> is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely influence the air quality in Tanzania.
url http://www.atmos-chem-phys.net/13/10325/2013/acp-13-10325-2013.pdf
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