An Evaluation of Atmospheric Aerosols in Kanana, Klerksdorp Gold Mining Town, in the North-West Province of South Africa

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An Evaluation of Atmospheric
Aerosols in Kanana, Klerksdorp Gold Mining
Town, North-West Province of South Africa
Brighton Kaonga and Eno E. Ebenso
North-West University (Mafikeng Campus),
South Africa
1. Introduction
Atmospheric aerosols have posed a health challenge by their presence in the atmosphere. In
order to control them, they have to be understood in terms of their interactions in the air,
their length of suspension and their transportation. It is true to say aerosols have been in the
atmosphere since the beginning of time itself. As long as there has been wind, particulate
matter has found itself in the air, attributed to nature aerosol emissions. Atmospheric
aerosols technically are considered to be suspension of fine solid or liquid particles in a gas
(Hinds, 1999). Particles in the air can change their size and composition by condensation of
vapour species or evaporation, coagulating with other particles by chemical reaction, or by
activation in the presence of water.
The production of atmospheric aerosols or atmospheric particulate matter is of great
concern. The effects of inhaling particulate matter which have been widely studied in
humans and animals include asthma, lung cancer, cardiovascular issues, and premature
death (Pope & Burnett, 2002). The size of the particle is a main determinant of where in the
respiratory tract the particle will come to rest when inhaled. Larger particles are generally
filtered in the nose and throat and do not necessarily cause problems, but particulate matter
smaller than about 10 micrometers (µm), referred to as PM10, can settle in the bronchi and
lungs and cause health problems. The 10 micrometer (µm) particle size does not represent a
strict boundary between respirable and non-respirable particles, but has been agreed upon
for monitoring of airborne particulate matter by most regulatory agencies (Seinfeld &
Pandis, 2006). Similarly, particles smaller than 2.5 micrometers, PM2.5, tend to penetrate
into the gas-exchange regions of the lung, and very small particles (< 100 nanometers) may
pass through the lungs to affect other organs. PM2.5 leads to high plaque deposits in
arteries, causing vascular inflammation and atherosclerosis — a hardening of the arteries
that reduces elasticity, which can lead to heart attacks and other cardiovascular problems
(Pope & Burnett, 2002).
Airborne particles undergo various physical and chemical interactions and transformation
(i.e. atmospheric aging), changes of particle size, structure, and composition (coagulation,
restructuring, gas uptake, chemical reaction). Particularly efficient particle aging occurs in
clouds, which are formed by condensation of water vapour on pre-existing aerosol particles
(cloud condensation and ice nuclei). Most clouds re-evaporate, and modified aerosol

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particles are again released from the evaporating cloud droplets or ice crystals (cloud
processing). If, however, the cloud particles form precipitation which reaches the Earth’s
surface, not only the condensation nuclei but also other aerosol particles are scavenged on
the way to the surface and removed from the atmosphere. This process, termed “wet
deposition”, is actually the main sink of atmospheric aerosol particles. Particle deposition
without precipitation of hydrometeors (airborne water particles)—that is, “dry deposition”
by convective transport, diffusion, and adhesion to the Earth’s surface—is less important on
a global scale, but is highly relevant with respect to local air quality, health effects
(inhalation and deposition in the human respiratory tract), and the soiling of buildings and
cultural monuments (Pöschl, 2005). Depending on aerosol properties and meteorological
conditions, the characteristic residence times (life-times) of aerosol particles in the
atmosphere range from hours to weeks.
Emission of particulate matter by natural means did not present as much health hazards
as compared to man-made activities. Natural emissions sources were wind dust, sea
sprays and natural fires or biomass burning. But this changed when man began to
develop himself; trying to make himself comfortable. The more he became comfortable
the more population increased, prompting new developments that consequently led to
activities that are now responsible for health threatening atmospheric aerosols. These
activities included the improved transportation system, industrial transformation, and
consumption of fuel etc. This pattern can be seen in the study area of interest, Kanana in
South Africa.
2. Purpose of the research study area
Literature shows that air pollution continues to threaten public health despite tighter
emission standards, closer monitoring of air pollution, and reduction of levels of certain
types of air pollutants. Averaged over the globe, anthropogenic aerosols (those made by
human activities) currently account for about 10 percent of the total amount of aerosols in
our atmosphere, (Pope and Burnett, 2002). The increased levels of fine chemical particle
concentration and composition in the air are linked to health hazards such as heart disease,
altered lung function and lung cancer. It is for this reason that an evaluation of the air
quality with regard to particulate matter was undertaken in Kanana area in the Klerksdorp
gold mining town of the North-West province of South Africa.
2.1 The case of Kanana, Klerksdorp (South Africa)
The North West Province, with its favourable geographical location close to the provincial
capital of South Africa, as well as its eco-tourism potential and the mining industry, is one of
South Africa’s most visited provinces. Touristic attractions include:
•
The Sun City/Pilanesberg complex, Magaliesberg, and Hartbeespoort. Recommended
new nodes include: Borakalalo Game Reserve, Vredefort Dome, Vaalkop Dam, and
Ganyesa /Kalahari.
•
Both foreign and local tourists visit the North-West Province. As such international
tourist bring in foreign exchange and so contribute greatly to the economy of the
country. Map of Kanana and description is shown below. Kanana lies in what is called
Orkney gold mining area, within Klerksdorp as can be seen in the map above (26° 58' 0"
South, 26° 38' 0" East).

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Klerksdorp Gold Mining Town, North-West Province of South Africa
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2.2 Environmental strains of the North-West Province
According to the State of the Environment Report overview (2002), North West Province,
South Africa is under pressure especially from:
•
The Ga-Rankuwa, Brits, Hartebeespoort and Rustenburg area due to industrial mining
and other developments. This area is also one of the tourism nodes in the Province that
needs to be sustained.
•
The main corridors for tourism are: Hartebeespoort-Rustenburg-Sun City-Madikwe
Game Reserve; Hartebeespoort-Rustenburg-Zeerust-Mafikeng-Lehurutshe,
Gauteng-Potchefstroom-Klerksdorp-Wolmaransstad-Bloemhof.
The State of the Air Report in South Africa (2005), list polluting sources as industrial and
commercial activities; electricity generation especially coal-fired and fuel-turbine power
stations; waste treatment and disposal that includes incineration; residential activities that
includes burning of coal, paraffin, liquid petroleum (LP) gas, dung and wood; transport
(petrol-diesel driven exhaust emissions, road dust raised by vehicles, etc); and agriculture.
On the other hand, there are admissions of health-risking particulate matter emissions into
the environment by industrial giants like the mines such that the public raised complaints
because of poor visibility and too much dust from the smelters and refineries, as well as
dust fallout from various tailings dams (Bullock, 2006).
and
3. Information on sources of particulate matter emissions
Like any other settled areas of the world, Rustenburg, another mining city in the North West
Province, has had its effects of human development on the quality of air. Before the onset of
industrialization, the air in the town was influenced by the natural phenomenon
occurrences; particulate matter in the atmosphere as a result of wind dust, fire-raised
atmospheric aerosols and particulate matter emissions as a result of human activities. But
the advent of increased population, pressures on the atmosphere also increased as a result of
increased human needs. The functioning and quality of the environment got affected as the
result of increased human needs. Increased population meant increase in land use such as
settlements, agriculture, and industry, to mention but a few.

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Industrial development in the form of mining appears to have had more influence in the
settlement in Rustenburg and the surrounding towns like Klerksdorp.
3.1 Mining
According to the North-West Freight Transport Databank, Rustenburg town alone contributes
about 70% platinum mining of the world. Chrome is also mined extensively. Klerksdorp is
mostly a gold mining town. South Africa as a whole is the largest producer of gold in the
world. The gold mining sector provides about 56% of miner’s employment in the country.
Mining activities produce toxic metals like mercury (Roulet et al., 1999) and so it is
important to establish the contribution of particulate matter in the atmosphere.


A


B
Fig. 1. (A & B): Mining processes as a source of particulate matter
Source: State of Air Report in South Africa (2005)

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Klerksdorp Gold Mining Town, North-West Province of South Africa
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3.2 Transport sector
As a result of large scale mining of platinum and gold, the transport sector has grown
tremendously. This includes public as well as commercial vehicles.


Fig. 2. Haulage track with particulate matter emissions
Source: State of Air Report in South Africa (2005)
3.3 Human sector
Mining sector offered great employment opportunities. This attracted people from even
surrounding areas thereby putting pressure on municipalities in terms of housing. As a
result all forms of settlements mushroomed – both planned and unplanned. Settlements
used fuel for cooking and warmth and so produced aerosols that reduced quality of the air
in the environment (figure 3).


Fig. 3. Domestic cooking as a source of particulate matter emissions
Source: State of Air Report in South Africa (2005)