| Summary: | Platinum mining activities contribute substantially to South Africa's economy since it
exceeded gold as economical contributor in 2001. Mining activities contribute to large
amounts of waste production in the form of tailings and rock waste, deposited in the
surrounding environment of the mine premises. Mining companies are held
responsible for damages caused to the surrounding environment. These companies are
required to introduce the cost of ecological rehabilitation in their operation costs as
well as compile an environmental management plan. Numerous attempts to
rehabilitate mine waste have proven unsuccessful. New and improved rehabilitation
techniques are required to facilitate in the rehabilitation of these mine spoils.
Woodchip-vermicompost produced from platinum mining wastes (woodchips and
sewage sludge) was used as an alternative amendment to inorganic fertilisers during
the rehabilitation of platinum mine tailings. The effectiveness of the woodchip-vermicompost
as an alternative amendment during the platinum mine tailings
rehabilitation were monitored using different ecosystem components. A natural veldt
in the vicinity of the mine area was randomly selected to serve as a reference site.
These ecosystem components selected have previously been shown to be effective as
indicators of ecosystem quality. The components selected for this study includes the
use of microbial enzymatic activity, microbial community structure, nematode trophic
structures, and other mesofaunal groups such as micro-arthropods. The physical and
chemical properties of the platinum mine tailings and reference area as well as the
vegetation cover of the platinum mine tailings were determined. Statistical and
multivariate analyses were use to determine the correlation between the dependent
microbial components and dominate independent chemical properties. Nematode
trophic structure, Maturity Index, and Plant-Parasitic nematode Index were used to
compare the two rehabilitation techniques in terms of nematodes as indicators. Microarthropods
family structures were used to compare the two amendments in terms of
diversity and abundance. Enzymatic activity was positively affected by the addition of
woodchip-vermicompost, than in the sites treated with inorganic fertilisers. The
microbial community structure showed no statistically significant (p < 0.05)
differences between the two amendments. A higher abundance of nematodes
especially plant-parasitic nematodes and bacterivorous nematodes were observed in the woodchip-vermicompost sites than in the inorganic fertilised sites. According to
the Maturity Index, both amendments became more enriched during the study period,
while the Plant-Parasitic nematode Index showed that the carrying capacity for plantparasitic
nematodes on the woodchip-vermicompost sites increased while it decreased
in the inorganic fertilised sites, which can be related to the decrease in vegetation
cover on the inorganic fertilised sites. Both coloniser (Prostigmata) and persister
(Cryptostigmata and Mesostigmata) groups of the micro-arthropods, as well as a
higher diversity of micro-arthropods, were present on the woodchip-vermicompost
sites whereas the inorganic fertilised sites showed only the presence of colonisers,
with a decrease in diversity and abundance of micro-arthropods over the study. The
colonisation of micro-arthropods may have been affected by the addition of
woodchip-vermicompost and vegetation cover, which contribute to the establishment
of suitable microhabitats for these soil biota. By intercorrelating the results, it may be
concluded that the addition of woodchip-vermicompost may be an essential part of the
rehabilitation process, by contributing to soil organic material to the ecosystem
system, which may improve the recolonisation of soil biota and ecosystem processes.
However further studies need to be conducted in order to determine the long-term
sustainability of the woodchip-vermicompost in providing organic material and
sustaining the ecosystem processes. The study also showed the necessity to integrate
various ecosystem components when evaluating ecosystem development due to the
unique role each component plays and the impact it may have on other components. === Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.
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