Abstract
M.Sc.
The impact of air pollution by power stations on water quality, just like any other source
of water pollution, is an issue of concern for all the water users since any degradation in
water quality affects the water's suitability for use. The study area in which Majuba
power station is located was chosen because it is in an area free of industrialisation, and
is also part of the Vaal catchment. This catchment area is very important because of its
water supply for Gauteng province and provides an ideal opportunity to monitor surface
water pollution from atmospheric sources such as power stations.
The purpose of this research is to investigate the chemical, physical and biological
quality of surface water in the vicinity (within a 31 kilometre radius) of Majuba power
station. The study will determine whether this power station is causing any salinity and
acidity problems at the chosen sampling sites. Salinity and acidity are water quality
problems associated with atmospheric pollution.
The aim of the study is to determine whether proximity to Majuba power station has an
effect on the surrounding surface water quality.
The research was conducted by means of water quality sampling, analyses and
assessment. Water quality samples were taken from six sites (Majuba 1 to Majuba 6) in
the vicinity of Majuba power station over a period of three years (1997 to 1999). The
approach was to take four samples in a year coinciding with the four seasons of the
year. Due to logistical problems only two sampling trips were undertaken, during 1997.
In 1998 and 1999 the full four sampling trips were undertaken however in some
instances the river was dry or was flooded hence no samples could be taken at the
affected sampling sites (although a trip to the sampling site was made). The biological
analyses where done on site using the biomonitoring technique while chemical analyses
were performed at the laboratory at Eskom.
The biomonitoring assessment was done using the biomonitoring technique. The
chemical results were assessed in terms of the suitability for use for the aquatic
environment. This was done by using the water quality guidelines for the aquatic
environment.
The chemical results indicated that in terms of salinity and acidity the site closest to the
power station, namely Majuba 1 had the worst water quality of the six sites. Majuba 1
also had the worst results in terms of biomonitoring. Majuba 2 indicated elevated salinity
levels. The other four sites, namely Majuba 3 to 6, did not indicate either salinisation or
acidification. However, the biomonitoring results at these sites indicated, with the
exception of Majuba 4, some deterioration in water quality. Majuba 4 had the best water
quality in terms of biomonitoring. Reasons for this could not be determined.
At present it is still premature to say whether acidity in the water is a problem. This is a
preliminary study and currently a more detailed multidisciplinary study that includes
disciplines such as atmospheric deposition, groundwater chemistry, soil profiles and
hydrology is being undertaken on the Upper Vaal catchment to comprehensively
determine the impact of air pollution from power stations on the surface water quality.
The proposal will be presented to the South African Water Research Commission. The
ultimate aim of the multidisciplinary study is to inform decision makers in water quality
management sector regarding the impact of air pollution on surface water quality, in
order for them to put in place abatement technologies or strategies to mitigate surface
water quality pollution.