18 research outputs found

    Southern African cosmogenic geomythology ("following a star") of the Zion Christian Church

    Get PDF
    Oral traditions and indigenous knowledge of the Limpopo Province in South Africa suggest a meteor event occurred in the area several decades ago. This relatively recent significant meteor event with associated features may have contributed to a revitalization of 13th century ancestral geomythology, also based on an astronomical event, and to an ideological transformation that augmented a vast sociopolitical belief system in sub-Saharan Africa.United States Mission to South Africahttp://www.tandfonline.com/loi/ttrs20hb201

    Temporal changes of particulate concentration in the ambient air over the city of Zahedan, Iran

    Get PDF
    Air pollution in developing countries has recently become a serious environmental problem, which needs more active air quality monitoring and analyses. To assess air quality characteristics over the city of Zahedan, southern Iran, airborne particulate matter (PM) concentrations with aerodynamic diameters of 0.82) for all seasons, implying that PM10 and PM2.5 may have the same source regions or that they are influenced by the same local conditions. In contrast, neutral correlation is found between PM10 and PM1.0 in autumn and winter. Taking into account that the annual variation of PM1.0 exhibits a clear pattern of peaking in winter and dropping in summer (in contrast to PM10), it is suspected that PM1.0 is of different origin than PM10 and mainly influenced by local anthropogenic emissions. The daily PM10 variation is strongly seasonally defined. The maximum PM10 concentrations occur in the morning hours during winter, autumn (September-November), and early spring (March), while in summer, PM10 concentrations increase significantly in the afternoon, closely associated with the intense northerly winds blowing from the desert. As far as the Air Quality Index (AQI) is concerned, its highest monthly values occur in summer, while they are reduced in winter. Desert dust aerosols are found to be the major component in determining the AQI in Zahedan. The analysis shows that 15.3% of the days are unhealthy for sensitive people, while 2% are considered as hazardous.http://www.springerlink.com/content/120982/nf201

    Links between observed micro-meteorological variability and land-use patterns in the highveld priority area of South Africa

    Get PDF
    Links between spatial and temporal variability of Planetary Boundary Layer meteorological quantities and existing land-use patterns are still poorly understood due to the non-linearity of air–land interaction processes. This study describes the results of a statistical analysis of meteorological observations collected by a network of ten Automatic Weather Stations. The stations were in operation in the highveld priority area of the Republic of South Africa during 2008–2010. The analysis revealed localization, enhancement and homogenization in the inter-station variability of observed meteorological quantities (temperature, relative humidity and wind speed) over diurnal and seasonal cycles. Enhancement of the meteorological spatial variability was found on a broad range of scales from 20 to 50 km during morning hours and in the dry winter season. These spatial scales are comparable to scales of observed land-use heterogeneity, which suggests links between atmospheric variability and land-use patterns through excitation of horizontal meso-scale circulations. Convective motions homogenized and synchronized meteorological variability during afternoon hours in the winter seasons, and during large parts of the day during the moist summer season. The analysis also revealed that turbulent convection overwhelms horizontal meso-scale circulations in the study area during extensive parts of the annual cycleThe authors would like to acknowledge the bilateral Norway–South Africa project 180343/S50 “Analysis and the Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes” co-funded by the South African National Research Foundation (NRF) and the Norwegian Research Council (NRC). A significant part of this work has been developed under the NRC project 191516/V30 “Planetary boundary layer feedback in the Earth's Climate System”, under the European Research Council Advanced Grant, FP7-IDEAS, 227915 “Atmospheric planetary boundary layers: physics, modeling and its role in the Earth system”, and under a grant from the Government of the Russian Federation (project code 11.G34.31.0048).http://link.springer.com/journal/703hb201

    Dust storms and their horizontal dust loading in the Sistan region, Iran

    Get PDF
    The Sistan region in southeast Iran is considered as one of the most active dust source regions in South west Asia. The strong ‘‘Levar’’ winds in summer favor the uplift of large quantities of dust from the Hamoun basin, which is located in the northern part of Sistan. After a dry period at the end of the 1999s, and due to land-use change and desiccation of the Hamoun lakes, the frequency and severity of dust storms have been significantly increased. Within this framework, this study analyses the aerosol characteristics, dust loading and air quality over the Sistan region. The dust loading was measured using dust traps up to four and eight meters height (with a one meter distance between the traps) at two locations near the Hamoun basin during the period August 2009 to July 2010. The results show large quantities of transported dust that strongly dependent on the duration of the dust events, and secondarily, on the wind speed and distance from the source region. The grain size distribution of the dusts reveals that the coarser calibers are found at the station nearer to Hamoun, while the large differences in the grainsize distribution found between the two stations indicate significant spatio-temporal variation in dust characteristics. Furthermore, to assess the air quality, Particulate Matter (PM10) concentrations were measured over Zabol city during September 2010 to July 2011, and the Air Quality Index (AQI) was obtained. Daily PM10 levels during intense dust storms rise up to 2000 lgm 3, even reaching to 3094 lgm 3, while the monthly mean PM10 variation shows extreme values (>500 lgm 3) for the period June to October. Analysis of the AQI shows that 61% of the days are associated with a high health risk, while 30.1% are even identified as hazardous.http://www.elsevier.com/locate/aeolianf201

    Assessment of chemical and mineralogical characteristics of airborne dust in the Sistan region, Iran

    Get PDF
    Windblown transport and deposition of dust is widely recognized as an important physical and chemical concern to climate, human health and ecosystems. Sistan is a region located in southeast Iran with extensive wind erosion, severe desertification and intense dust storms, which cause adverse effects in regional air quality and human health. To mitigate the impact of these phenomena, it is vital to ascertain the physical and chemical characteristics of airborne and soil dust. This paper examines for the first time, the mineralogical and chemical properties of dust over Sistan by collecting aerosol samples at two stations established close to a dry-bed lake dust source region, from August 2009 to August 2010. Furthermore, soil samples were collected from topsoil (0–5 cm depth) at several locations in the dry-bed Hamoun lakes and downwind areas. These data were analyzed to investigate the chemical and mineralogical characteristics of dust, relevance of inferred sources and contributions to air pollution. X-ray Diffraction (XRD) analysis of airborne and soil dust samples shows that the dust mineralogy is dominated mainly by quartz (30–40%), calcite (18–23%), muscovite (10–17%), plagioclase (9–12%), chlorite ( 6%) and enstatite ( 3%), with minor components of dolomite, microcline, halite and gypsum. X-ray Fluorescence (XRF) analyses of all the samples indicate that the most important oxide compositions of the airborne and soil dust are SiO2, CaO, Al2O3, Na2O, MgO and Fe2O3, exhibiting similar percentages for both stations and soil samples. Estimates of Enrichment Factors (EFs) for all studied elements show that all of them have very low EF values, suggesting natural origin from local materials. The results suggest that a common dust source region can be inferred, which is the eroded sedimentary environment in the extensive Hamoun dry lakes lying to the north of Sistan.http://www.elsevier.com/locate/chemospherehb201

    Draft genome sequence of chloride-tolerant Leptospirillum ferriphilum Sp-Cl from industrial bioleaching operations in northern Chile

    Get PDF
    IndexaciĂłn: Web of Science; PubMedLeptospirillum ferriphilum Sp-Cl is a Gram negative, thermotolerant, curved, rod- shaped bacterium, isolated from an industrial bioleaching operation in northern Chile, where chalcocite is the major copper mineral and copper hydroxychloride atacamite is present in variable proportions in the ore. This strain has unique features as compared to the other members of the species, namely resistance to elevated concentrations of chloride, sulfate and metals. Basic microbiological features and genomic properties of this biotechnologically relevant strain are described in this work. The 2,475,669 bp draft genome is arranged into 74 scaffolds of 74 contigs. A total of 48 RNA genes and 2,834 protein coding genes were predicted from its annotation; 55 % of these were assigned a putative function. Release of the genome sequence of this strain will provide further understanding of the mechanisms used by acidophilic bacteria to endure high osmotic stress and high chloride levels and of the role of chloride-tolerant iron-oxidizers in industrial bioleaching operations.https://standardsingenomics.biomedcentral.com/articles/10.1186/s40793-016-0142-

    The low potential bioleaching of chalcopyrite with ferroplasma JTC3

    Get PDF
    M.Sc.The leaching of chalcopyrite (CuFeS2) concentrate in a ferrous iron promoted aerobic/anaerobic controlled low potential sulphate system was investigated by using the duel metabolic (aerobic ferrous iron oxidation and anaerobic ferric iron reduction) capabilities of Ferroplasma JTC 3. The experimental work conducted in this study was divided in three sections. The first section focussed on the identification and phylogenetic classification of Ferroplasma JTC 3, first identified amongst a mixed microbial population in a 55 oC pyrite concentrate-fed bioreactor operated at Johannesburg Technology Centre (BHP Billiton, JTC). Based on the 16S rDNA sequence and the phylogenetic analysis, Ferroplasma JTC 3 represents a new species member under the genus of Ferroplasma. The optimal growth temperature of Ferroplasma JTC 3 was determined at approximately 53 oC (moderate thermophile). The second section of this study focussed on the isolation, basic metabolism and growth conditions of Ferroplasma JTC 3, specifically directed towards the chalcopyrite leaching related experimental work. An important aspect of this study was to compare low potential chalcopyrite leaching (potential below 400 mV vs. Ag/AgCl) against high potential chalcopyrite bioleaching (potential above 600 mV vs. Ag/AgCl) in terms of the rate of copper extraction. Microbial growth and the rate of ferrous iron oxidation are essential in order to maintain a high potential during an extended leach period, which was typically the case in the high potential chalcopyrite leaching experiments performed during this study. Ferroplasma JTC 3 required yeast extract as sole carbon source (chemo-heterotrophic) for growth via aerobic ferrous iron oxidation. Taking into account no carbon dioxide enrichment via aeration, chemo-autotrophic growth by means of ferrous iron oxidation was poor with carbon dioxide as sole carbon source. The anaerobic metabolism of Ferroplasma JTC 3 was utilized in assisting with solution potential control during the low potential chalcopyrite leaching work. The anaerobic metabolism enabled the reduction of ferric iron (decrease redox potential) in the presence of elemental sulphur and yeast extract. Elemental sulphur was shown to be a requirement for Ferroplasma JTC 3 assisted ferric iron reduction, which was not influenced by different ferrous/ferric iron based redox potentials. The third section covers the main focus of this study, which was the low potential leaching of chalcopyrite in combination with the metabolic capabilities of Ferroplasma JTC 3. The major challenge of low potential chalcopyrite leaching in an acidic environment is maintaining the solution potential below the critical upper limit (400 mV vs. Ag/AgCl) of the low potential window for prolonged periods of time. The reason is the slow chemical oxidation of ferrous iron in the presence of oxygen, which increases the leach solution potential above the critical upper limit before complete copper dissolution is obtained. The aim of this study was to maintain a low solution potential environment in a bioreactor via a programmable electronic gas control system, capable of creating an aerobic environment until the solution potential would reach the upper low potential limit (400 mV vs. Ag/AgCl) due to ferrous iron oxidation (chemically or via Ferroplasma JTC 3) and then switch to an anaerobic environment. During the anaerobic environment, the aim was to decrease the solution potential to a lower potential set point via chalcopyrite oxidation by ferric iron (ferric iron reduction) and by employing the ferric iron reduction metabolism of Ferroplasma JTC 3. With the particular aerobic/anaerobic solution potential control system, in conjunction with the metabolic capabilities of Ferroplasma JTC 3, the solution potential could be controlled within the critical low potential region, but no chalcopyrite leaching could be obtained during the anaerobic phase. The lack of chalcopyrite leaching during the anaerobic phase was due to inability of ferric iron to act as oxidant of chalcopyrite after the mineral was pre-leached in the preceding aerobic phase. The “oxidative acid leach” mechanism was identified as the dominant leach reaction that prevailed during the aerobic low potential stage in each of the aerobic/anaerobic control experiments conducted, in which oxygen acts as oxidant of chalcopyrite (electron acceptor) in the presence of protons (H+) (acidic environment), instead of ferric iron in an acid environment. The “boundary potential”, which is the maximum solution where no electron flow occurred to the ferrous/ferric couple from “pre-leached” chalcopyrite, was identified in the region of 450 mV (Ag/AgCl). Under the experimental conditions within this study, the leaching of chalcopyrite within the aerobic phase of the aerobic/anaerobic control experiments was superior to the Ferroplasma JTC 3 mediated high potential leaching, but complete copper dissolution could not be obtained with the combined aerobic and anaerobic system. Ferric iron precipitation as a function of pH was proposed as a tool for solution potential control, instead of controlling the potential by limiting oxygen to the leach system. In controlling the solution potential via pH, almost complete copper dissolution from chalcopyrite was obtained, while maintaining the solution potential below the critical upper limit of the low potential region

    Begrafnisregte in die konteks van die Afrika-gewoontereg en die rol van die testamentopsteller

    No full text
    Religious and cultural practices and values play an important role in funerals and how they should be conducted. This creates considerable conflict between heirs and family members, especially those living under a system of African customary law, when someone dies and funeral arrangements have to be made. This whole issue can be brought under the concept of burial rights. This "right" to bury a deceased family member can be quite problematic in two ways: first, when the question of who should bury the deceased must be decided, and secondly when the question of where the deceased must be buried has to be decided. Not only do these two questions give rise to conflict among the family members of the deceased, but they also lead to considerable confusion in the courts, especially where there is no agreement on the exact principles to be appliedwww.litnet.co.za/begrafnisregte-in-die-konteks-van-die-afrika-gewoontereg- en-die-rol-van-die

    Characterization of Moringa oleifera Leaf Powder Extract Encapsulated in Maltodextrin and/or Gum Arabic Coatings

    No full text
    The encapsulation of bioactive-rich plant extracts is an effective method of preventing their damage or loss of activity during processing and storage. Here, the techno-functional properties of microcapsules developed from Moringa oleifera leaf powder (MoLP) extract (core) with maltodextrin (MD), gum Arabic (GA), and a combination (MDGA) (coatings) were assessed. The bulk and tap density were 0.177, 0.325 and 0.297 g/mL and 0.13, 0.295 and 0.259 g/mL for GA, MD and MDGA microcapsules, respectively. Flowability properties of microcapsules indicated an intermediate flow except for GA which had a poor flow. The moisture content of the microcapsules ranged from 1.47% to 1.77% with no significant differences (p > 0.05) observed. All the microcapsules had high water solubility (86.35% for GA to 98.74% for MD and 90.51% for MDGA). Thermogravimetric analyses revealed that encapsulation enhanced the thermal stability of the core material. The X-ray diffraction analysis revealed that the microcapsules and extracts have an amorphous nature, which was validated by the surface morphology analysis that showed amorphous, irregular, and flake-like attributes except for MDGA microcapsules which had slightly spherical and agglomerated surfaces. The Fourier Transform Infra-Red spectra of the microcapsules showed the presence of C-O and O-H aromatic rings as well as amine groups. New spectra were observed at 1177, 1382 and 1411 cm−1 for MDGA, MD and GA, respectively, after encapsulation, which connotes a slight modification in the chemical structural pattern after encapsulation. Storage stability tests (28 days at 4, 25 and 40 °C) showed that the microcapsules were most stable at 4 °C and the stability differs significantly (p ≤ 0.05) with coating material type and temperature with MDGA showing better storage stability than others. Altogether, the attributes of the MDGA microcapsules were comparatively better than either MD or GA alone. The present data, therefore, demonstrate an effective encapsulation process for MoLP extract that can serve as fortificants in processed food products where MoLP may be used
    corecore