Leon van Rensburg

Can diatom-based pollution indices be used for biomonitoring in South Africa? A case study of the Crocodile West and Marico water management area

The inclusion of diatoms into the current suite of biomonitoring tools in use in South Africa, as well as the use of European and other diatom indices in South Africa, and in particular the Crocodile and West Marico water management area, is discussed. The indices, when compared to chemical analyses, proved useful in providing an indication of the quality of the investigated waters. Several widely distributed diatom species were shown to have similar ecological tolerances in South Africa when compared to Europe. Although most of the diatoms encountered in the study were cosmopolitan, several possibly endemic species were recorded. The occurrence of endemic species, not included in existing diatom indices may lead to miscalculations of diatom indices. It is concluded that although diatom indices developed in Europe and elsewhere are useful at the present to indicate water quality, a diatom index unique to South Africa including endemic species will have to be formulated.

Recommendations for the collection, preparation and enumeration of diatoms from riverine habitats for water quality monitoring in South Africa

Diatoms have become important organisms for monitoring freshwaters and their value has been recognised for cross-border water quality monitoring in the European Union. If South Africa is to include diatoms in the current suite of bioindicators, then thorough testing of diatom-based techniques is required. This paper provides guidance on methods through all stages of diatom collection, preparation and examination for the purposes of water quality assessment.

Earthworm (Eisenia Fetida) bioassay to assess the possible effects of platinum tailings disposal facilities on the environment along a gradient

Platinum mines produce large amounts of inorganic tailings containing high levels of metals which are disposed of on tailings disposal facilities (TDFs) and there is no information available on their possible effects on the surrounding terrestrial environment. The aim of this study was to do an earthworm bioassay of soils along a gradient from a TDF over a period of 28 days in terms of growth, reproduction and metal accumulation. After 28 days the earthworms in the soil collected up to 1 km away from the TDF showed a significant (P < 0.05) decrease in bodyweight and in the soil 2−5 km away showed no effect. The earthworms in the soil collected 15 km away from the TDF showed a significant (P < 0.05) increase in bodyweight. The mean hatching success of cocoons was significantly (P < 0.05) higher in the soils further away from the TDF viz. 15 km > 3−5 km > 2−0 km. Cr, Cu, Ni and Zn concentrations in the soils collected in the soils on the platinum TDF (TDF − 15 km in the case of Zn) were higher, while Cd, Co and Pb were lower when compared to screening benchmarks proposed by the U.S. Dept. of Energy. The presence of these metals in a mixture, however, makes it extremely difficult to assess their effects. All of the metals had low bioconcentration factors (BCFs) viz. < 0.01 (CR, Ni and Pb), 0.01 (Co), 0.33−0.5 (Cd), 0.01−0.08 (Cu) and 0.18−0.29 (Zn). It can be concluded that platinum mining, with TDFs as source of contamination, has negative effects on the environment but further studies are needed to assess the exact extent of these effects.

Effects of different soil ameliorants on Karee trees (Searsia Lancea) growing on mine tailings dump soil – Part I: Pot trials

Rehabilitation of mine tailings dams is often a challenge due to a lack of nutrients and a poor humus reservoir prevailing in tailings soils. This is especially true for establishing longer lived species such as trees. For these reasons the effects of different soil ameliorants (woodchips compost, vermicompost, mature sewage sludge), added to the root system of Karee (Searcia lancea) saplings were tested in pot trials. Those pots were filled with platinum and gold tailings substrate as well as red clay soil, respectively. For three months plants remained in a greenhouse and were subsequently moved to a test field outside. Throughout the test period regular chl a fluorescence measurements were taken and subjected to JIP-test quantifying changes in photosynthetic vitality status. Additionally, growth measurements and one-off leaf analysis were carried out. Test plants growing on mine tailings experienced an up to 35% higher average photosynthetic vitality (PIABS) and improved nutrient supply, when treated with mature sewage sludge. Consequently, sewage sludge treated plants showed a higher biomass build-up rate and an up to 55% higher diameter growth, compared to control. In summary the experiments present a low cost alternative for reforestation enterprises on platinum and gold tailings dams in South Africa.

Assessing the ecotoxicity of gold mine tailings utilizing earthworm and microbial assays

Problems associated with mining are the disposal of wastes on tailing disposal facilities (TDFs). The aim of this study was to determine the ecotoxicity of gold mine tailings by using earthworm bioassays, earthworm biomarkers and enzymatic analyses. End points included changes in biomass, reproduction, lysosomal membrane stability, tissue metal concentrations, and selected enzymatic activities. Results indicated high concentrations of Ni in the material as well as bioaccumulation of lead and arsenic in the earthworm body tissue after exposure. Enzymatic activity was higher in revegetated tailings than in unrehabilitated tailings. It was concluded that TDF and surrounding areas have an acidic pH which affects earthworms and metal bioavailability. Soil enzymatic activities were a sensitive indicator of metal pollution in mining areas. Growth, reproduction and lysosomal membrane stability of earthworms have also been shown to be sensitive end points to assess the ecotoxic effects of gold TDF.

An exploration of cultural beliefs and practices across the Southern Ground-Hornbill’s range in Africa

BackgroundThis article explores cultural beliefs and practices related to the Southern Ground-Hornbill (SGH) (Bucorvus leadbeateri) in nine southern and east-African countries.MethodsA qualitative, thematic content-analysis approach was followed. Ninety-eight participants took part in the study. Interviews and group discussions were used as the main data gathering methods. Each interview was digitally recorded and transcribed. Data were analysed by means of thematic content analysis.ResultsThe main themes that emerged from the data analysis indicated that beliefs and practices relate to the SGH as being (a) a bringer or signifier of death/destruction/loss/ deprivation, with the bird commonly being regarded as a bad omen of evil spirits and announcer of calamities; (b) a protector against evil spirits, against lightning and against drought; (c) an enabler/causer of altered perceptions, which include remote viewing, foreseeing the future, and creating an illusion; and (d) a timekeeper that announces the beginning and end of a working day and of seasonal changes.ConclusionsKnowledge about the use of the SGH in cultural practices can contribute to conservation efforts in at least two significant ways: Firstly, beliefs and practices that were identified in this study as having potentially protective consequences for the SGH can now be specifically targeted and strengthened in future interventions. Secondly, destructive beliefs and practices that were identified can now be changed by means of the implementation of an intervention programme in countries where it is needed.

Developing a site selection tool to assist reintroduction efforts for the Southern Ground– Hornbill Bucorvus leadbeateri

The Southern Ground-Hornbill Bucorvus leadbeateri (SGH) is regarded as Vulnerable globally and Endangered in South Africa as a result of losing close to 70% of its range and 50% of its historic population in the country. One of the conservation tools being used to address this issue and restore the population to its historic range is reintroductions. The aim of this study was to identify and prioritise probable reintroduction sites in the Mopane Bioregion and the Limpopo and Mpumalanga sections of the Lowveld Bioregion of South Africa (all in the Savanna Biome), by using a niche-based modelling technique (Maxent) combined with GIS analyses. Suitable SGH habitat was determined for farms in the study area and evaluated for the absence of mappable threats. Three priority areas were identified for reintroductions. These areas are in a near-natural state, offer sufficient habitat, are free of mappable threats and are close to formally protected areas. Field surveys of these three priority areas are needed next to validate their suitability for reintroduction purposes. This is the first spatially explicit reintroduction plan for the SGH that has been developed and will contribute to conservationists’ efforts to conserve the SGH.

Reforestation—Quality Improvement of Contaminated Mining Soil

Most sub-Saharan countries are influenced by either drought or heavy rainfall, as well as poor soil quality and anthropogenic and industrial factors. South Africa is one of the countries in the region where the greatest impact of mining on the environment is observed. These environmental impacts are obvious and need to be addressed during each phase of environmental planning, especially in rural development and improving agriculture sectors. The environmental impacts of mining in South Africa are, in general, increased concentrations of heavy metals and changes of pH in both impacted soils and in water. Mining processes coupled with weather conditions affect the agricultural and forestry sector by impacting water and soil quality. Therefore, there is need to decontaminate mining soils and to improve soil fertility for better agricultural and environmental services. In this regards the addition of different organic fertilizers to improve soil fertility, and as soil ameliorant in contaminated platinum and gold tailings, allowed the indigenous tree species—Searsia lancea to grow despite the high levels of contamination. In a laboratory trial with both types of tailings the combination of different fertilizers and cultivation techniques reduced up to 50% heavy metal contamination and increased ~140% microbiological activities. These experiments show a sustainable use of trees combined with fertilizers to decontaminate mine soil while producing a resource (wood) and lowering carbon dioxide, which have impacts on preventing contamination of surrounding areas by Aeolian transport (sandstorms, etc.).

Risks and Opportunities of Sustainable Biomass and Biogas Production for the African Market

Almost all important natural resources – e.g. oil, diamonds, gold, platinum, coal, copper, ore, phosphate etc. – including rare earth metals for industries functioning in the international arena, are available on the African continent. Roughly 15% of the total world market of resources is in Africa. International interest in Africa is via the relatively political and economic stable countries of the ‘Africa 7’ – South Africa, Botswana, Morocco, Ghana, Nigeria, Egypt and Kenya. According to Doing Business Report and the World Bank, statistically, about 60% of the resources from agriculture in Africa are still reserves. Based on the international trends to support developing countries by establishing a market for biomass production, with the aim of advanced energy production, resource efficiency, emission reduction, it has to be balanced with the internationally supervised and important sector of food security. As markets in Africa show, the agricultural sector, including cattle production, to be a very strong market, biomass residues such as cow manure and other organic substances are available as a cheap or free by-product. To turn these natural resources into a valuable commodity, it simply has to be converted by fermentation into biogas usable for cooking or electricity and fertiliser usable for private gardening. Current knowledge has proved how effective and simple biomass and biogas production can be. The output of one ton of silage can produce up to 200 m3 of biogas with a productivity of 5.0–7.5 kWh electricity per m3 of biogas. Cow manure as a source of waste product is available at an annual amount of 7.5–21.0 m3 per animal with a productivity of about 30 m3 of biogas including 56% of methane (CH4). A micro-biogas production facility is viable with a capacity of about 1 kWh – this is equivalent to the digestion of cow manure from seven milk cows. Using biomass additionally supports the reduction of greenhouse gases (GHG) particularly CO2, NH4, N2O. Compared to CO2, NH4 has got 25-times higher and N2O 298-times higher Global Warming Potential (GWP). The reduction of these greenhouse gases as a side benefit of biomass production provides an indication of how positive this strategy could be for both the agricultural sector as well and general public.

Simulation of Carbon Consumption by Biological Models

Since the 1970’s, the shortage of available and usable resources has been seen as the ‘limit to growth’. Since then, the regenerative-ability of the environment—its ability to absorb harmful substances and waste products, has achieved a similar standing. Critical ecological examination must take not only the beginning, but also the end of the production chain into consideration, and thereby give equal weight to the exhaustion of important production materials (energy, raw materials) as well as to the over-stretching of the ecological reproduction capacity of the Earth. To recognize the carbon influence in production processes, it is necessary to balance anthropogenic material streams. For production processes and material recycling, the smallest common and not further reducible indicator is carbon. With knowledge of requirements, it is possible to reduce carbon consumption as a becoming scarce natural resource and fossil fuel which is used in different production process. Therefore, the material fluxes as the product of density (mass by volume) and hydrologic flow velocity (distance by time) must be known for every place and time of the production process. This investigation shows that the annual input and output of carbon in processes are almost balanced. With this carbon-balance, it is possible to identify resources and depressions of carbon and to point out approaches for optimization. Mostly material streams show a flow of valuable materials which can be merchandized if the quality is still right. This also reflects the strategy of cradle-to-cradle. To evaluate these anthropogenic impacts of pollutants on the environment or material streams in the natural circle, it is indispensable to use the benefits of computer systems—in particular artificial intelligence. Most of impact factors are time related and therefore difficult to calculate and to optimize in a natural environmental system. Use of evolutionary algorithms as a part of the artificial intelligence to simulate, estimate and evaluate pollutants or specific materials makes it possible to evaluate the impact on the environment and to optimize material streams in nature or recycling streams.