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| Titel |
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 |
| VerfasserIn |
S. L. Mkoma, K. Kawamura, P. Q. Fu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 20 ; Nr. 13, no. 20 (2013-10-23), S.10325-10338 |
| Datensatznummer |
250085764
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| Publikation (Nr.) |
 copernicus.org/acp-13-10325-2013.pdf |
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| Zusammenfassung |
| Atmospheric aerosol samples of PM2.5 and PM10 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 46–52% and 87–13%, respectively. The mean mass concentrations of
PM2.5 and PM10 were 28 ± 6 μg m−3 and 47 ± 8 μg m−3
in wet season, and 39 ± 10 μg m−3 and
61 ± 19 μg m−3 in dry season, respectively. Total carbon (TC)
accounted for 16–19% of the PM2.5 mass and 13–15% of the
PM10 mass. On average, 86 to 89% of TC in PM2.5 and 87 to
90% of TC in PM10 was OC, of which 67–72% and 63% was found to
be water-soluble organic carbon (WSOC) in PM2.5 and PM10,
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+) (r2 = 0.56–0.75), OC
(r2 = 0.75–0.96) and WSOC (r2 = 0.52–0.78). The K+ / OC
ratios varied from 0.06 to 0.36 in PM2.5 and from 0.03 to 0.36 in
PM10 with slightly higher ratios in dry season. Mean percent ratios of
levoglucosan and mannosan to OC were found to be 3–4% for PM2.5 and
PM10 in both seasons. We found lower levoglucosan / K+ ratios and
higher K+ / 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+ 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. |
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