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| Titel |
Characterisation of plumes from the Johannesburg-Pretoria megacity within the regional South African context |
| VerfasserIn |
J. P. Beukes, V. Vakkari, P. G. Van Zyl, A. D. Venter, M. Josipovic, P. Tiitta, K. Jaars, J. J. Pienaar, M. Kulmala  , D. Worsnop, L. Laakso |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066513
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| Zusammenfassung |
| Introduction
The Johannesburg-Pretoria conurbation in South Africa is inhabited by more than 10 million
people, making it one of the 40 largest metropolitan areas in the world. Conurbations of this
magnitude have been defined as megacities (Molina and Molina, 2004). However, similar
to many developing world megacities, relatively little has been published on the
Johannesburg-Pretoria conurbation. Megacities are not only important from a local air quality
(health) perspective, but also since they have a global atmospheric impact (Butler and
Lawrence, 2009).
Approach
In this paper, the Johannesburg-Pretoria megacity source region, as well as other source
regions in the interior of South Africa was defined, as observed from a relatively new super
site for atmospheric measurements (www.welgegund.org) that is located at Welgegund (26Ë
34’10"S, 26Ë 56’21"E, 1480Â m.asl). This site is approximately 70km west of the
Johannesburg-Pretoria megacity source region. Plumes from the megacity source region
arriving at Welgegund were identified via obtaining and overlaying back trajectories for a two
year period. The back trajectory arrival times were correlated to in situ measurement to
chemically and physically characterize the plumes. The characteristics of the megacity
plumes were also compared to plumes from other defined source regions, as well as the
regional background.
Results
Results indicated that the plumes arriving at Welgegund after passing over the
Johannesburg-Pretoria megacity source region had much higher concentrations of gaseous
pollutant species which include NO, NO2, O3, SO2, CO and anthropogenic VOC’s, as well as
aerosol total organic content, SO42-, NO3- and NH4+, if compared to the regional
background. PM1 aerosol absorption (black carbon), scattering and number concentrations
indicated similar trends.
Comparison of the Johannesburg-Pretoria megacity source region with other defined
source regions indicated that plumes from the megacity was as polluted as plumes from the
more well-known source regions i.e. the Mpumalanga Highveld and the Vaal Triangle, which
have been proclaimed as a national air pollution hotspots in terms of the South
African National Environmental Management: Air Quality Act (Government Gazette
Republic of South Africa, 2005; Government Gazette Republic of South Africa,
2007).
The above-mentioned results obtained for the Johannesburg-Pretoria conurbation indicate
serious air quality and climate change related impacts for the human population and regional
ecosystems.
References
Molina, M. J., and Molina, L. T.: Megacities and atmospheric pollution, J. Air Waste
Manage. Assoc., 54, 644–680, 2004.
Butler, Timothy M. and Lawrence, Mark G.: The influence of megacities on global
atmospheric chemistry: a modelling study, Environ. Chem. 6, 219-225, doi:10.1071/EN08110,
2009
Government Gazette Republic of South Africa, 24 February 2005 No. 27318, available at:
http://www.info.gov.za/view/DownloadFileAction?id=61585 (accessed 13 Dec 2011),
2005.
Government Gazette Republic of South Africa, 4 May 2007 No. 29864, available at:
http://www.info.gov.za/view/DownloadFileAction?id=73046 (accessed 13 Dec 2011), 2007. |
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