Abstract
The Witbank-Middelburg coalfields have the highest concentration of coal-mines in South
Africa. Endorheic grass pans typically occur in this area. Most of the easily accessible coal
seams in this area have already been mined leaving only the sensitive areas, like the grass
pans, available for mining. The Elandspruit Pan is a grass pan in this area that is currently the
only known breeding site of the Giant Bullfrog (Pixicephalus adspersus) in the Mpumalanga
Province.
Open-cast coal mining is already taking place within 1 km of the pan and further rich coal
deposits occur beneath the pan which represents future mining interests. Atmospheric
deposition of pollutants associated with the open-cast mining activities and coal-fired power
stations are expected to impact negatively on the pan.
Water samples were collected at the start and end of the study period of six months
(November 2010 - April 2011) and analysed for constituents including suiphates, nutrients
and metals. The pH, temperature, conductivity (EC) and Total Dissolved Solids (TDS) and
dissolved oxygen (DO) were measured fortnightly from November 2010 - April 2011.
Diatoms samples were collected once a month and the dominant diatoms were identified and
their abundance scored. Results were compared to a reference site, a pan located on a game
farm in a comparatively unimpacted area about 20 km to the north of Elandspruit Pan.
The most dominant diatoms were Cocconeis engelbrechtii and Gomphoneina affine at both
Elandspruit Pan and the reference pan. The EC at both the pans was relatively low between
44 iS/cm and 113 tS/cm with pH below 7.
This study showed that aquatic biota such as diatom associations can successfully be used as
biological indicator of ecosystem health and that Elandspruit Pan is impacted by
anthropogenic activities. Atmospheric pollution takes place at the pan, but it is not only from
coal mining and related activities. The diatom assemblages indicated eutrophication and
salinity as the major variables impacted....
M.Sc. (Aquatic Health)