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An analytical investigation of the biophysical factors that inhibit successful ecological restoration of gold tailings dams
Get PDFThesis (M. Environmental Science)--Potchefstroom University for Christian Higher Education, 2003.The sphere of influence of gold tailings dams has a considerable detrimental impact on the environmental quality of numerous aquatic and terrestrial ecosystems and directly or indirectly affects human living standards. It is therefore of utmost importance to find a persistent modus operandi to restore this wasteland and to mitigate the negative results associated with these tailings dams, which mainly include air, soil and water pollution. The inherent nature of gold tailings material though, does not submit to the expectations of ecological principles derived from natural systems after ecological restoration is applied. It is therefore necessary to investigate and describe this unnatural medium with its associated characteristics, and the responses of vegetation as reflected by ecosystem development. Through this ecological assessment, restoration techniques could be refined, which could lead to sustainably viable solutions. This study investigates various integrated facets of gold tailings revegetation, focusing on the soil-vegetation interaction, and the proposal of numerous variables to describe and evaluate ecological performance within the framework of sustainability. Through the assimilation of basic quantitative data and monitoring of restoration performance at different time intervals, the stability and long-term effectiveness of ecological restoration of gold tailings media at various stages of the remediation curve is assessed. An overview of restoration indicates that only a more holistic approach in the form of ecological reconstruction should drive ecological remediative processes, and using existing scientific criteria, which are based on basic ecological principles, self-sustaining ecosystem development could be achieved. Results from soil analysis, vegetation abundance and species performance data of pot trials and field surveys, were multivariately and statistically analysed to establish significant limiting and interacting variables, which determine the performance of revegetated systems. The influence of these topoedaphic variables, which included macro-and microclimatological factors, soil physical and chemical parameters and eventually plant species resemblance, was established through the assessment of experimental growth models, and soil and vegetation dynamics on established revegetated gold tailings dams. The manipulation of these variables through soil profile reconstruction, which implies physical fraction reshuffling and either chemical dilution or enhancement, as well as aspect (microclimatological) and soil chemical changes, showed major responses to seedling abundance, species composition and secondary successional associated characteristics. The major existing need for ecological standards criteria were also addressed through the assessment of a statistically sound method, which was based on scientifically derived floristic information.
Several ecological indicators of functional return were identified and the method used was further extended not only to indicate the re-occurrence of ecological sensitivity indicators, but also to give clarity on the functional performance and ecological blending of the revegetated areas. The question surrounding the characterisation of these ecologically dissimilar areas as separate systems with different (new) ecological principles was, however, highlighted through this study and future research should focus on defining these principles as well as short-and long-term modelling of revegetated areas. The contribution of this research to restoration ecology is significant with regards to the intensive investigation and explanation of characteristics and processes that will drive ecological succession and determine restoration success.Master
'n Strategie vir die rehabilitasie van versteurde mynbougebiede in Suidelike Afrika
Get PDFPhD (Plant- en Bodemwetenskappe), North-West University, Potchefstroom CampusA STRATEGY FOR THE REHABILITATION OF AREAS IN SOUTHERN
AFRICA DISTURBED BY MINING ACTIVITIES
A literature study revealed that revegetation (grassing) of
areas disturbed by mining activities already occurred during
the early thirties. Most of the relevant research has been
conducted abroad. In the RSA, all the initial work was done
on gold mine sand dumps.
Although other methods to stabilize the dust generating dumps
had also been applied, it was finally agreed upon that a
proper vegetation cover is the only permanent solution.
During previous years, all initial revegetation attempts were
voluntary. During the fifties, law enforcement became applicable
in most countries, forcing all mines to revegetate
areas disturbed by their activities.
In the RSA several laws have already existed since 1956, e.g.
the Mines and Works Act (Act 27 of 1956). Although these laws
are not directly aimed at revegetation, they can be applied
to this aspect. In 1980 the law became more stringent and it
became evident that revegetation is not the solution to all
problems, due to deterioration of the vegetation occurring on
many of the revegetated areas.
In order to comply with the demands of the constantly
tightening law, research on the rehabilitation of disturbed
areas started during 1984. The study area included several
mines in the RSA as well as mines situated within the borders
of Leboa and Ka Ngwane. The ecological diversity of these
localities is stressed by the differences in climate, topography,
geology and vegetation. Some of the mines are
situated in areas with an annual rainfall of approximately
400 mm in comparison with others with a precipitation of
more than 800 mm.
Presently, research on the revegetation of road reserves already
indicates that methods and recipes which were successfully
applied in countries with a moderate climate and high
rainfall, do not necessarily produce the same results in the
RSA with its dry and hot summers. This is one of the main
reasons why the use of indigenous grass species was seen as a
priority.
From the results obtained in experiments on the mine dumps
and slimes dams, it was clear that hardy indigenous species
were also not capable of solving all the problems. The negative
results led to a more holistic approach by which the
habitat of plants was taken into consideration.
Special attention was given to soil-associated problems at
various mines. These problems included aspects such as
gradient and length of slopes, particle size of overburden,
chemical imbalances of tailings, temperature of tailings,
spontaneous combustion, etcetera.
Although only a few of the more important factors had been
studied, the results of this research revealed a number of
general
principles which can be applied in devising
rehabilitation strategies. The results can also be used as a
basis for more detailed studies on the various aspects.
The study has shown that every effort should be made to
reinstate a situation as near as possible to the natural
situation. In order to establish a stable and self-sustaining
vegetation on a mine dump, it will be necessary to create a
habitat where ecological factors comply with the tolerance
limits of the species to be used. This approach implies that
the revegetation or grassing alone will not be the answer to
the existing problems of recovering disturbed areas, but that
complete rehabilitation would be of utmost importance.Doctora
Sosiologie en sosiografie : 'n vergelykende studie /
No full textProefschrift Pretoria.Met bibliografie
Cyanobacteria and algae of gold mine tailings in the North-West Province of South Africa
No full textCryptogamic crusts are important components in arid and semiarid lands and could play
a vital role in the rehabilitation of mine tailings. The aim of this study was therefore to investigate
the occurrence of cyanobacteria and algae on gold mine tailings storage facilities in the Northwest
province in South Africa that are characterized by extreme geotechnical and geochemical conditions.
Samples for chemical, physical as well as biological analysis were collected from un-rehabilitated
tailings as well as a chrono-sequence of biologically rehabilitated tailings materials. Results
show that Chlorella (Trebouxiophyceae), Chlorococcum (Chlorophyceae) and Klebsormidium
(Klebsormidiophyceae) species were present at all the rehabilitated sampling sites. The dominant
genera on these sites were Chlamydomonas (Chlorophyceae), Chlorococcum, Klebsormidium and
Phormidium (Phormidiaceae). No cyanobacterial or algal growth was found on freshly deposited
tailings material and only a few species such as Chlamydomonas sp., Chlorella ellipsoidea Gerneck,
Chlorococcum sp., Microcoleus vaginatus (Phormidiaceae) and a Phormidium species were found
on un-rehabilitated material. It was evident that the time of rehabilitation did not have an influence
on the algal as well as cyanobacterial species present in the tailings material and that the presence
of a grass cover on the rehabilitated sites may have provided a microclimate enhancing the growth
of these organisms.http://www.schweizerbart.de/journals/nova_hedwigiahttp://www.schweizerbart.de/papers/nova_hedwigia/detail/97/80928/Cyanobacteria_and_algae_of_gold_mine_tailings_in_the_Northwest_Province_of_South_Africahttp://dx.doi.org/10.1127/0029-5035/2013/011
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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