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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
agricultural and biological sciences
Re-evaluating the NO
2
hotspot over the South African Highveld
South African Journal of Science, Volume 108, No. 11-12, Year 2012
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Description
Globally, numerous pollution hotspots have been identified using satellite-based instruments. One of these hotspots is the prominent NO 2 hotspot over the South African Highveld. The tropospheric NO 2 column density of this area is comparable to that observed for central and northern Europe, eastern North America and south-east Asia. The most well-known pollution source in this area is a large array of coal-fired power stations. Upon closer inspection, long-term means of satellite observations also show a smaller area, approximately 100 km west of the Highveld hotspot, with a seemingly less substantial NO2 column density. This area correlates with the geographical location of the Johannesburg-Pretoria conurbation or megacity, one of the 40 largest metropolitan areas in the world. Ground-based measurements indicate that NO2 concentrations in the megacity have diurnal peaks in the early morning and late afternoon, which coincide with peak traffic hours and domestic combustion. During these times, NO2 concentrations in the megacity are higher than those in the Highveld hotspot. These diurnal NO2 peaks in the megacity have generally been overlooked by satellite observations because the satellites have fixed local overpass times that do not coincide with these peak periods. Consequently, the importance of NO2 over the megacity has been underestimated. We examined the diurnal cycles of NO2 ground-based measurements for the two areas - the megacity and the Highveld hotspot - and compared them with the satellitebased NO2 observations. Results show that the Highveld hotspot is accompanied by a second hotspot over the megacity, which is of significance for the more than 10 million people living in this megacity. © 2012. The Authors.
Authors & Co-Authors
Lourens, Alexandra S.M.
South Africa, Potchefstroom
North-west University
Butler, Timothy M.
Germany, Mainz
Max Planck Institute for Chemistry
Beukes, Johan Paul
South Africa, Potchefstroom
North-west University
van Zyl, Pieter Gideon
South Africa, Potchefstroom
North-west University
Beirle, Steffen
Germany, Mainz
Max Planck Institute for Chemistry
Wagner, Thomas K.
Germany, Mainz
Max Planck Institute for Chemistry
Heue, Klaus Peter
Germany, Mainz
Max Planck Institute for Chemistry
Pienaar, Jacobus J.
South Africa, Potchefstroom
North-west University
Fourie, Gerhardus D.
South Africa, Sasolburg
Sasol Technology Pty Ltd
Lawrence, Mark G.
Germany, Potsdam
Research Institute for Sustainability – Helmholtz Centre Potsdam Rifs
Statistics
Citations: 85
Authors: 10
Affiliations: 4
Identifiers
Doi:
10.4102/sajs.v108i11/12.1146
ISSN:
00382353
e-ISSN:
19967489
Research Areas
Environmental