Showing papers in "Transactions of The Royal Society of South Africa in 2015"
TL;DR: In this article, the authors review the hypotheses on the evolution of the topography and environment and concentrate on the fossil record, especially pollen, wood, charcoal, leaves and biomarkers.
Abstract: Long-term trends in climate, hydrology and geomorphology contributed to the formation of the current biomes of southern Africa. The Neogene terrestrial fossil record is patchy, due to the geomorphological evolution of the subcontinent and the restricted distribution of suitable sediment deposits. Here we review the hypotheses on the evolution of the topography and environment and concentrate on the fossil record, especially pollen, wood, charcoal, leaves and biomarkers. Tectonic studies suggest a lower relief landscape than at present at the onset of the Neogene. Southern Africa was drained by two river systems – the Kalahari and the Karoo Rivers – and was affected by an initially weak, cool Benguela current along the western coastline, gradually promoting an aridity trend along the southwestern coast. The Cape region during the Miocene, when the Great Escarpment began to evolve, was characterised by humid, subtropical forests not unlike those still occurring on the much wetter subtropical eastern shore o...
62 citations
TL;DR: The development of the ‘mosaic habitat’ – loosely defined as a range of different habitat types, such as woodlands, riverine forest and savannah within a limited spatial area – in studies of human evolution over the last 60 years or so is explored.
Abstract: The habitats preferred by hominins and other species are an important theme in palaeoanthropology, and the ‘mosaic habitat’ (also referred to as habitat heterogeneity) has been a central concept in this regard for the last four decades. Here we explore the development of this concept – loosely defined as a range of different habitat types, such as woodlands, riverine forest and savannah within a limited spatial area– in studies of human evolution in the last sixty years or so. We outline the key developments that took place before and around the time when the term ‘mosaic’ came to wider palaeoanthropological attention. To achieve this we used an analysis of the published literature, a study of illustrations of hominin evolution from 1925 onwards and an email survey of senior researchers in palaeoanthropology and related fields. We found that the term mosaic starts to be applied in palaeoanthropological thinking during the 1970’s due to the work of a number of researchers, including Karl Butzer and Glynn Isaac , with the earliest usage we have found of ‘mosaic’ in specific reference to hominin habitats being by Adriaan Kortlandt (1972). While we observe a steady increase in the numbers of publications reporting mosaic palaeohabitats, in keeping with the growing interest and specialisation in various methods of palaeoenvironmental reconstruction, we also note that there is a lack of critical studies that define this habitat, or examine the temporal and spatial scales associated with it. The general consensus within the field is that the concept now requires more detailed definition and study to evaluate its role in human evolution.
39 citations
TL;DR: The South African National Survey of Arachnida (SANSA) was initiated in 1997 as discussed by the authors to document and describe the arachnid fauna of South Africa, to consolidate all the available data on South African arachns into one relational database and to make this biodiversity information available to science; and to address issues concerning their conservation and sustainable use.
Abstract: Biodiversity is one of the most important concepts in contemporary biology, with a broad range of applications. In November 1995, South Africa ratified the Convention on Biological Diversity (CBD). Signatories are obligated to develop a strategic plan for the conservation and sustainable use of biodiversity. To meet the requirements of the CBD, the South African National Survey of Arachnida (SANSA) was initiated in 1997. This national project has several aims: to document and describe the arachnid fauna of South Africa; to consolidate all the available data on South African arachnids into one relational database and to make this biodiversity information available to science; and to address issues concerning their conservation and sustainable use. Extensive sampling took place and the SANSA database contains a wealth of biodiversity data that are used to provide answers to ecological questions. Presently 71 spider families, 471 genera and 2170 species are known from South Africa, representing approximately...
38 citations
TL;DR: In this paper, the authors have shown that evapotranspiration (ET) can be accurately estimated in arid environments from remotely sensed data, such as MODIS data, based on the Surface Energy Balance System (SEBS) algorithm.
Abstract: Accurate, reliable and continuous understanding of water utilisation by different land cover types in arid environments is critical for water loss accounting to ensure sustainable water management in the face of the changing climate. Remote sensing provides a lucrative alternative for mapping and estimating the spatial and temporal distribution of water loss across the catchment. The results of this study have shown that evapotranspiration (ET) can be accurately estimated in arid environments from remotely sensed data, such as Moderate Resolution Imaging Spectroradiometer (MODIS) data, based on the Surface Energy Balance System (SEBS) algorithm. This study observed significant spatial and temporal variations in ET across the south western part of Zimbabwe. The findings from this study, therefore, underscore the importance of using cheap and readily available remotely sensed data for estimating and mapping the variations in ET in arid-environment areas found mainly in developing countries.
26 citations
TL;DR: A phylogenetic analysis of the Langebaanweg seals was undertaken to better understand their relationships and island hopping is proposed as a means for phocid seal migration to South Africa.
Abstract: A phylogenetic analysis of the Langebaanweg seals was undertaken to better understand their relationships The fossil phocid seals from Langebaanweg nest within the Lobodontini and form a clade that includes Ommatophoca rossii (Ross seal) The Langebaanweg seals' relationships are unresolved in both analyses Two analyses were performed producing differing results The prior weights analysis produced a clade that included the Ross seal (Ommatophoca rossii) + the Langebaanweg seals + the remaining Antarctic lobodontines The implied weights analysis (k=3) produced a clade including the South American seals (Hadrokirus and Piscophoca) + the Ross seal (Ommatophoca rossii) + the Langebaanweg seals, which is part of the polytomy that includes the clade including the leopard seal (Hydrurga leptonyx) and the crabeater seal (Lobodon carcinophaga) and Acrophoca longirostis In both analyses the monophyletic group LBW-F + LBW-D + LBW-A is retained while the monophyletic group LBW-C + LBW-B from the first analysis i
26 citations
TL;DR: Two new, independent analyses, using in-lake total phosphorus or satellite-measured chlorophyll-a, respectively, reveal that between 41% and 76% of total storage is eutrophic or hypertrophic, in stark contrast to a claimed 5% by the responsible government agency.
Abstract: The socio-economic well-being of South Africa is largely dependent on reservoir lakes. Contrastingly, the country lacks reservoir management skills and training, with a generation having passed since there was limited activity in this field. This review introduces two new, independent analyses which, using in-lake total phosphorus or satellite-measured chlorophyll-a, respectively, reveal that between 41% and 76% of total storage is eutrophic or hypertrophic. This is in stark contrast to a claimed 5% made by the responsible government agency (Department of Water and Sanitation). Data and information on the incidence and toxicity of cyanobacterial blooms are sparse, yet severe problems exist. There is a concentration of focus on water quantity, with absent parallel consideration of the additional limitations posed by poor water quality. The most seriously impacted reservoirs are located in the economic heartland of South Africa, which has an extant regional water quality crisis. The reasons behind the start...
24 citations
TL;DR: In this article, modern and fossil pollen grains extracted from bat guano in Arnhem Cave are evaluated for their potential as a palynological archive and the possible influence of insectivorous bat behaviour on the pollen contents of their dung.
Abstract: Modern and fossil pollen grains extracted from bat guano in Arnhem Cave are evaluated for their potential as a palynological archive and the possible influence of insectivorous bat behaviour on the pollen contents of their dung. Four out of seven fossil guano samples from this cave were productive. The inconsistent preservation of pollen in bat guano layers may be due to deterioration through various mechanisms, including combustion. The samples that did contain pollen support previous conclusions, derived from pollen in spring deposits, about Holocene palaeoenvironmental changes in central Namibia. Two samples of modern bat dung yielded pollen spectra with a greater proportion of woody plant pollen than grass pollen in comparison with the fossil guano material, indicating denser tree cover than in the past, which may be due to the possible effect of modern farming practices. Differences in the pollen composition in dung of different bat species foraging in a relatively homogenous African savanna suggest ...
18 citations
TL;DR: In this paper, the authors describe the sorption of metal ions using a montmorillonite-rice husk composite as a novel adsorbent and compare it with the unmodified, alkaline and acid-treating, unmodified and acid treated MTs.
Abstract: This work describes the sorption of metal ions using a montmorillonite-rice husk composite as a novel adsorbent. The adsorption capacity of the new adsorbent was compared with the unmodified, alkaline and acid treated montmorillonite. Scanning electron microscopy showed an increase in the porous nature of the adsorbent modified with rice husk. The Fourier transform infrared spectra showed an alteration of the structure of the montmorillonite-rice husk adsorbent. Brunauer–Emmett–Teller (BET) analysis showed a sharp increase in the surface area of the montmorillonite from 55.76 to 118.01 m2/g and the total pore volume from 0.0688 to 0.114 cm3/g. It showed a decrease in the average pore diameter from 49.35 to 38.64 A and enhancement of the cation exchange capacity from 90.78 to 96.17 meq/100 g for the new adsorbent. The change in solution pH, initial metal concentration, adsorbent dosage, contact time and solution temperature affected the adsorption process. The Freundlich model gave a better fit than the La...
18 citations
TL;DR: In this article, the authors discuss past agricultural damage to the arid ecosystems, which is currently being followed by environmental changes and biodiversity losses associated with the new role of desert ecosystems as power factories (gas, uranium, wind and sun energy), mineral resources or retreats from the city.
Abstract: Using the Karoo as an example, we discuss past agricultural damage to the arid ecosystems, which is currently being followed by environmental changes and biodiversity losses associated with the new role of desert ecosystems as power factories (gas, uranium, wind and sun energy), mineral resources or retreats from the city. Development-related damage includes road building, vegetation clearing, soil compaction, water extraction and pollution. We present our views on prospects for ecologically and socially appropriate rehabilitation to rebuild complex and resilient ecosystems where recovery rate is constrained by aridity and rainfall unpredictability. We conclude that, to achieve intergenerational equity and conserve unique ecosystems, considerable investment in arid zone rehabilitation is needed to keep pace with the demands of a rapidly growing human population.
16 citations
TL;DR: In this article, the impact of fast-track land reform in Zimbabwe on land-use and land-cover changes was investigated by characterising the spatio-temporal changes in land cover between 2000 and 2010 as a result of the land reform policies.
Abstract: An understanding of the role of land policies as major drivers behind tree species diversity reduction in southern Africa is still rudimentary. This study, therefore, sought to assess the aftermath of the fast track land reform programme in Zimbabwe on land-use and land-cover changes. Specifically, we characterised the spatio-temporal changes in land-cover between 2000 and 2010 as a result of the land reform policies in Quagga Pan Ranch, Masvingo Province, Zimbabwe. Secondly, we assessed the effects of the fast track land reform programme of 2000 on tree species diversity. Finally, we attempted to establish whether there was selective logging in newly resettled areas and also sought to understand the reasons behind selective tree logging. Land-cover changes were characterised after classifying Landsat satellite images of 2000 and 2010. Tree species data were collected using quadrats in newly resettled and unsettled areas for determining the state of selective logging. Questionnaires and observations were ...
14 citations
TL;DR: A high-resolution palynological record from the Sea of Galilee (Israel) roughly spanning the Last Glacial Maximum (LGM) obtained from a trench dug in the vicinity of the well-dated prehistoric site of Ohalo II (23-24 ka cal. BP) combined with detailed litho-stratigraphic and magnetic susceptibility analyses is presented in this article.
Abstract: A new high-resolution palynological record from the Sea of Galilee (Israel), roughly spanning the Last Glacial Maximum (LGM) obtained from a trench dug in the vicinity of the well-dated prehistoric site of Ohalo II (23–24 ka cal. BP) — combined with detailed litho-stratigraphic and magnetic susceptibility analyses — provides evidence of vegetation, lake levels and climate change in the northern Jordan Valley. The sequence begins with laminated marls of the last Lake Lisan high stand and ends with the near-shore deposits containing the prehistoric site. Palynologically, the early phase of the high stand (pollen zone 1) is characterised by high-AP (mainly Quercus ithaburensis), reflecting a relatively humid climate. During its later part (zone 2), the increase in Artemisia indicates a regional drying. Several fluctuations in lake levels and humidity are recorded (pollen zones 3–4) prior to human occupation at the prehistoric camp, during a renewed humid climate (pollen zone 5); in its early phase Quercus ca...
TL;DR: Recommendations are made on how long-term monitoring of the Brown Locust could be continued and broadened to encompass knowledge gaps, potentially useful indicators of ecosystem integrity and climate change.
Abstract: Three decades ago a locust conference in Kimberley deliberated on the Brown Locust Locustana pardalina (Walker), its biology, feeding ecology, population dynamics, outbreak extent and frequency, swarm movements and artificial control of outbreaks. The current paper evaluates recommendations made at this conference. In contrast to the high levels of effort and funding allocated for over a century to the control of locust swarms by means of insecticides, relatively little has been spent on research of the Brown Locust, not even to verify and characterise the actual problem. Methods of locust control have improved and environmental impacts of current applications are somewhat reduced. A critical, comprehensive cost-benefit analysis, necessary to evaluate whether costly control measures and continuous interventions are warranted, has still not been conducted. Many other knowledge gaps remain, such as the ecological significance of locusts as one of the remaining swarming phenomena of the Karoo. Swarms of locu...
TL;DR: The authors explored the early work and influence of van Zinderen Bakker and his first PhD student, J.A. Coetzee and tracked the course of emerging science through to the present day.
Abstract: Quaternary palynology as a discipline evolved historically in northern hemisphere temperate environments where conditions favourable to the preservation of pollen facilitated its application to the reconstruction of vegetation history and, through interpretation, palaeoenvironments. Such studies in Africa started much later and, in southern Africa, were only initiated when E.M. van Zinderen Bakker joined the Department of Botany in what is now known as the University of the Free State in the late 1940s. This paper explores the early work and influence of van Zinderen Bakker and his first PhD student, J.A. (Joey) Coetzee and tracks the course of the emerging science through to the present day. The sustained basis of van Zinderen Bakker's work was pollen analysis and the laboratory quickly developed a substantial pollen reference collection to support the research. Forays into tropical Africa were followed by work on organic sediments in South Africa. The relatively limited occurrence of suitable wetland de...
TL;DR: In this paper, the benefits of an algorithmic approach using the method of symmetry analysis introduced by Sophus Lie in the nineteenth century are demonstrated with several examples chosen from the field of financial mathematics.
Abstract: Derivatives in finance have become pervasive in recent decades. Tremendous impetus was given to this aspect of finance by the pioneering papers of Black and Scholes (1973) and Merton (1973) and has attracted considerable interest since. In general the evolution partial differential equations were solved by means of the traditional methods of partial differential equations and by ansatz previously useful in similar contexts. Here we illustrate the benefits of an algorithmic approach using the method of symmetry analysis introduced by Sophus Lie in the nineteenth century. We demonstrate the utility of this analytic approach with several examples chosen from the field of financial mathematics.
TL;DR: In this paper, the authors tested whether and to what extent spectral vegetation indices derived from new generation high-spatial resolution multispectral sensors (WorldView-2 and GeoEye-1) estimate indigenous forest wood volume when compared to medium-sparse broadband sensors (Landsat 5 Thematic Mapper) based on two savanna woodland types in Zimbabwe.
Abstract: Continuous, accurate estimation and mapping of forest dendrometric characteristics such as wood volume using remote sensing is fundamental for better understanding the role of forests in the carbon cycle and for informed management strategies for forests and woodlands. In this study, we tested whether and to what extent spectral vegetation indices derived from new generation high-spatial resolution multispectral sensors (WorldView-2 and GeoEye-1) estimate indigenous forest wood volume when compared to medium-spatial resolution broadband sensors (Landsat 5 Thematic Mapper) based on two savanna woodland types in Zimbabwe. Subsequently, the best regression model relating wood volume and vegetation indices was applied to map the indigenous forest wood volume of two study sites. Our results showed that spectral vegetation indices derived from new generation multispectral sensors of high resolution yielded plausible indigenous forest wood volume estimates when compared to spectral vegetation indices derived fro...
TL;DR: In this paper, the authors focus on the work of Louis Scott and co-workers on the palynology of present-day and past savanna fossil-pollen sites in southern Africa.
Abstract: This paper focuses on the work of Louis Scott and co-workers on the palynology of present-day and past savanna fossil-pollen sites in southern Africa. Evidence for the persistent though fluctuating presence of the pollen of extant species of trees indicates species survival under marked variations in climate over the past 200 ka, but variable assemblage of communities over time, at any one site. This, with contemporary information on the genetics and demographics of savanna tree species, requires that ecologists today must see the savanna as an individualistic, ecogenetic or eco-evolutionary community. Further, present-day savanna communities are the outcome of recent and older history, requiring that ecology must encompass the methods of historical science.
TL;DR: The sedge, Cladium mariscus, has been identified in Middle Stone Age deposits at the shelter Sibudu, South Africa, where the leaves were used as "bedding" as discussed by the authors.
Abstract: The sedge, Cladium mariscus, has been identified in Middle Stone Age deposits at the shelter Sibudu, South Africa, where the leaves were used as “bedding” – an informal floor covering for various activities. Cladium mariscus nutlets were recovered from layers 73 000–39 000 years old and are likely to have entered the shelter on the plants harvested for bedding. This paper explores the possibility that, in addition to the use of Cladium mariscus leaves for bedding, the nutlets were collected for food. The underground storage organs and nutlets of many sedge species are eaten by contemporary people and they are known to have been eaten in the past at other sites. Nutritional analysis of the nutlets and rhizomes of Cladium mariscus indicates their potential as a food source, notwithstanding the small size of the nutlets. Although there is no evidence for the preparation of Cladium mariscus for consumption at Sibudu, the abundant nutlets produced by the plants, their nutritional value and the ease of harvesti...
TL;DR: In this paper, the authors reviewed literature on the use of remote sensing in monitoring groundwater resources in sub-Saharan Africa, and they sought to adopt methods that would provide timely and spatially explicit information on the distribution and magnitude of groundwater for informed and restoration strategies.
Abstract: The increased demand and abstraction of groundwater resources is a cause for concern in sub-Saharan Africa. Timely mapping and monitoring of the quantity and annual abstraction levels of groundwater resources are critical if sustainable groundwater resources management is to be fully achieved. Conventionally, groundwater mapping has been conducted based on field surveys that depend on geomorphic interpretation expertise and ancillary data analysis. Considering that these methods are costly, laborious and time-consuming makes remote sensing a better alternative for mapping groundwater resources, given the imminent need of knowledge on the status of this resource. It is therefore essential to adopt methods that would provide timely and spatially explicit information on the distribution and magnitude of groundwater for informed and restoration strategies, particularly in resource constrained Africa. This study, therefore, sought to review literature on the use of remote sensing in monitoring groundwater acro...
TL;DR: In the early 1930s, an upper right third molar (M3) together with a calotte and fragmented facial bones of an adult fossil hominin was recovered during excavations at Florisbad as mentioned in this paper.
Abstract: In the early 1930s an upper right third molar (M3) together with a calotte and fragmented facial bones of an adult fossil hominin was recovered during excavations at Florisbad. The M3 is one of the few well-dated teeth associated with cranial remains from the late Mid-Pleistocene in southern Africa and as such provides a valuable addition to the fossil dental record of this region. Here we provide a detailed description of the tooth based on standard measurements and 3D images derived from high resolution micro-high resolution micro-focus X-ray tomography. Our results show that the Florisbad M3 falls within the size range of African Homo erectus. It is slightly larger than other peri-contemporary M3s known from Africa that date from the Middle to Late Pleistocene. Like them, however, it also falls within the size range of recent, large-toothed African populations. These results suggest the maintenance of selective pressures favouring large teeth in some African populations until the present.
TL;DR: In this paper, a more circumspective approach engendering a look at exposure outcomes of other fugitive components of industrial emissions in the township, specifically carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2), is presented.
Abstract: Exposure to noxious industrial fumes and its health consequences are of critical environmental concern for residents of the Umlazi Township of South Durban in South Africa. Diverse industries located around the Township include those of transportation, petroleum refining, chemical, paper, sugar, plastics, textiles, galvanizing and paint producing. Pollution from these industries takes many forms, with the most potent fugitive emissions coming from the transportation industry. Since previous studies on noxious emissions from this highly industrialized Township have focused largely on the health effects of sulphur dioxide (SO2) emissions, it is believed that a more circumspective approach engendering a look at exposure outcomes of other fugitive components of industrial emissions in the Township, specifically carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2), is desirable. Continuous monitoring of air quality over the Township was performed using an Extract, Transform and Load (ETL) gas analyser, ...
TL;DR: The main aim of the study is to analyze the contribution of small-scale vegetable production in the livelihood of the farmers in Port St John's as well as the challenges and agronomic practices of farmers as mentioned in this paper.
Abstract: The main aim of the study is to analyze the contribution of small-scale vegetable production in the livelihood of the farmers in Port St John's as well as the challenges and agronomic practices of farmers. This region is a rural area with no major industry to provide job for the people thus vegetable cultivation is the main source of food and income. Despite this, the sector is facing a lot of problems such as poor market structure for farmer's products, lack of farm loans, lack of farm input such as fertilizer and modern seed as well as the problem of pest and diseases and heavy rainfall in summer which sometime destroys cabbage and spinach. The research established that most of what was cultivated was consumed at home and only the surpluses were sold. Based on the findings, it was concluded that vegetable production is an important aspect in the life of the local population but it is being affected by numerous problems. In order to sustain this improvement, farmers need to be adequately educated; extens...
TL;DR: The diversity of ectomycorrhizal fungi and their host associations across a fallow crono-sequence of 1–14 years in the mid-Zambezi valley area, Zimbabwe is investigated to support reports on low host specificity among the observed ectomy corollary fungi.
Abstract: Fallowing creates land mosaics characterised by vegetation communities at different stages of succession. Such mosaics are expected to harbour mycorrhizal associations that reflect host species composition and diversity. We investigated the diversity of ectomycorrhizal fungi and their host associations across a fallow crono-sequence of 1–14 years in the mid-Zambezi valley area, Zimbabwe. Five ectomycorrhizal fungi species: Lactarius gymnocarpus, Lactarius sp., Boletus sp., Thelephora terrestris and Amphinema byssoides were recorded from 13 tree species from six families: Combretaceae, Ebenaceae, Fabaceae, Simaroubaceae, Rhamnaceae and Tiliaceae. The results indicated low host specificity among the observed ectomycorrhizal fungi. A Spearman Rank correlation test showed no significant correlation (p > 0.05) between fallow age and ectomycorrhizal status. The Raup–Crick similarity cluster indicated an interaction between fallow age and ectomycorrhizal fungi status on tree species. Our results support reports ...
TL;DR: The International Year of Chemistry (IYC) 2011 was to improve the public's image and understanding of the subject of chemistry as mentioned in this paper. But the image of chemistry around the world has deteriorated, and it has become apparent that the negative impact that loose handling of chemicals and waste, on occasions, had on the environment.
Abstract: Much to the dismay of chemists, and those employed in the field, it has become apparent that the image of chemistry around the world has deteriorated. One of various reasons for this may be the negative impact that loose handling of chemicals and waste, on occasions, had on the environment. One of the objectives of the International Year of Chemistry (IYC) 2011 was to improve the public's image and understanding of the subject. The concept of Green Chemistry was formulated 24 years ago in the USA to tackle challenges facing chemistry in the 21st century. It has brought about a major positive shift in the way chemists think, process, handle and dispose of chemicals. Since its formulation, the returns on investments in Green Chemistry are increasing rapidly. It may eventually hold the key to Africa's future sustainability of economic, social and environmental development if regional educational needs are recognised and addressed, and if investment in Green Chemistry increases in the areas of research and de...
TL;DR: Current studies place cholesterol among several major measures of body health, the others being body weight, regular exercise, non-smoking, normal blood pressure and blood glucose levels (even modest elevations warn of risk for future diabetes).
Abstract: Diet is only one of the aspects of a healthy lifestyle. Fundamental observations were made in 1955 in the Metabolic Research Unit at Groote Schuur Hospital. When high fat diets were given to healthy subjects with low blood cholesterol levels, added beef dripping, beef muscle or butter sustainably increased blood cholesterol levels, while added olive oil restored normal low levels. Increasing blood cholesterol levels in apparently healthy persons that are followed up for many years increases heart attack risks (Framingham studies). Current studies place cholesterol among several major measures of body health, the others being body weight, regular exercise, non-smoking, normal blood pressure and blood glucose levels (even modest elevations warn of risk for future diabetes). For weight reduction, the Noakes and the New Atkins diets show the way. For long term dietary health, the beneficial Mediterranean pattern of eating emphasises high levels of fruit and vegetables, fish rather than meat, olive oil and nut...
TL;DR: In this paper, thermal desorption reactions were investigated for natural petroleum formation and it was concluded that these reactants extensively rearranged to form similar mixtures of surface-bonded species.
Abstract: Selected organic reactants, including n-dodecanol and stearic acid adsorbed on clays at low temperature (300 K), decomposed on heating (>400 K) to yield alkane product mixtures: thermal desorption reactions. These products showed that, while adsorbed, reactant hydrocarbon chains underwent cracking, isomerisation and hydrogen transfers. Because product distributions obtained from several different reactants were closely similar, it is concluded that these reactants extensively rearranged to form similar mixtures of surface-bonded species. From this evidence, we suggest that thermal desorption provides a realistic chemical mechanism for natural petroleum formation: it is well-known that some minerals promote kerogen breakdown. To investigate the feasibility of this mechanism in nature, the following comparisons were made. Qualitative: Our model thermal desorption reactions yielded alkanes in the C5–C8 range that are usual constituents of crude oils. Quantitative: Product yields were sufficiently large to ex...
TL;DR: In this paper, the absorption of zinc in contaminated soils was studied using one-year Arizona cypress seedlings, which were placed in vases, after the passage of each 55-day time period from the growth of the seedlings.
Abstract: Phytoremediation is the technology of using plants for decontamination of heavy metals and their accumulation in the different tissues and organs of plants. The contamination resulting from heavy metals is of great significance due to its sustainability in the environment. The absorption of zinc in contaminated soils was studied using one-year Arizona cypress seedlings, which were placed in vases. After the passage of each 55-day time period from the growth of the seedlings, the shoots (leaves and stem), roots and soil of the seedlings were sampled. Results were studied using an analysis of variance (ANOVA) test and Duncan's test. The highest mg/l concentration rate of zinc in Arizona cypress organs in the first time period in the shoots, roots and soil was 61.67 mg/kg, 60.1 mg/kg and 12.45 mg/kg, respectively and in the second time period in the shoots, roots and soil was 142.86 mg/kg, 85.94 mg/kg and 12 mg/kg, respectively. Based on the research, Arizona cypress is appropriate for refining zinc metal po...
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TL;DR: In this paper, the authors present a book for senior learners and their teachers which is the sixth title in the Cambridge's Indigenous Knowledge Library (CKL) and is a busy book packed with colourful illustrations, charts and tables.
Abstract: Compiled for senior learners and their teachers, this is the sixth title in Cambridge's Indigenous Knowledge Library It is a busy book, packed with colourful illustrations, charts and tables The richly factual text includes 'Did you know?' boxes,activity suggestions and guides to the pronunciation of long scientific words
TL;DR: In this paper, the authors used multispectral remote sensing Landsat images to determine landcover changes in one of the rural areas of Masvingo Province in Zimbabwe, using a maximum likelihood classifier.
Abstract: The rural population of Zimbabwe has been growing rapidly since the country gained independence in April 1980. This increased pressure and degradation of the land; hence there was a need to sustain the growing population and its subsequent impacts on rural areas. This led to the implementation of the land reform programme in 2000, which intended to provide more land for settlement and crop production. Although this was successful to a certain extent, investigation is required to determine the changes in spatial and temporal variations in landcover for better management and allocation of natural resources to sustain the rural population and economic development. This study, therefore, used multispectral remote sensing Landsat images to determine landcover changes in one of the rural areas of Masvingo Province in Zimbabwe, using a maximum likelihood classifier. A post-classification change detection technique was also used to produce change through cross-tabulation. The findings of this study have demonstra...
TL;DR: Living with eutrophication in South Africa : a review of realities and challenges, Transactions of the Royal Society of South Africa 70(2) 2015 is reviewed.
Abstract: Living with eutrophication in South Africa : a review of realities and challenges, Transactions of the Royal Society of South Africa 70(2) 2015 : pp. 155-171 : erratum
TL;DR: The southern African landscape is an incomparable natural laboratory for the geomorphologist and attracted the attention, early in the 20th century, of several prominent scholars including geologist Alex du Toit, the empirically and descriptively-minded geographer John Wellington and the geomorphicologist Lester King.
Abstract: South Africa holds an important place in the development of geomorphology as a distinct field of inquiry focused on understanding the Earth's physical landscapes. As Bernard Moon notes in the Foreword to this volume (p. i), "The southern African landscape is an incomparable natural laboratory for the geomorphologist." Encompassing a wide range of landscape types and landforms of "a prodigious range of ages," it attracted the attention, early in the 20th century, of several prominent scholars including geologist Alex du Toit, the empirically and descriptively-minded geographer John Wellington and the geomorphologist Lester King, all of whom produced important books.