Academy of Science of South Africa (ASSAf): Open Journal Systems
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Quantification of toxic metals in cropland soil using X-ray fluorescence
No full textWe aimed to assess toxic heavy metals in soil samples from cropland in Weenen (KwaZulu-Natal, South Africa) using X-ray fluorescence (XRF) spectroscopy. The metal contents in the soil samples were detected and quantified by wavelength dispersive XRF (WD-XRF) spectroscopy. On average, the values of all elements (mg/kg) were: Al (91.4 ± 6.9), Ba (0.488), Ca (16.8 ± 5), Fe (39.3 ± 0.8), K (15.7 ± 0.04), Mg (10.1 ± 0.3), Mn (0.6), Na (8.0 ± 1), P (1.3 ± 0.4), Si (458 ± 8) and Ti (5.6 ± 0.3). Toxic metals such as Hg, Cd, As, Pb, and Cr were not detected in the soil samples. The macronutrient P, which is capable of causing eutrophication in water bodies, was present at a low level in soil samples. The metal contents in both control and field samples were comparable, suggesting that the metals were mostly of lithogenic origin and not entirely influenced by anthropogenic activities. The metal levels we detected were within the limits reported to be safe by other studies.
Significance:
Although they are within the detection range, the toxic heavy metals mercury, cadmium, arsenic, lead and chromium, which enter the environment through the use of fertilisers on agricultural land, were not detected in this WDXRF spectrometry analysis. The remaining elements detected are lithogenic and non-anthropogenic, as the field and control samples had comparable concentrations. Nitrogen was not quantified, but phosphorus was present in a low concentration, so the field water run-off into the water bodies need not directly lead to water pollution in the area studied
Effect of manganese-rich solid waste on soil phosphorus availability applied as monopotassium and rock phosphate in two contrasting soils
No full textManganese (Mn) mining produces a large amount of Mn-rich solid waste contributing to soil and groundwater pollution. Adding Mn-rich waste to soils could reduce mining pollution by allowing specialised plants to take up this mineral for growth, that is, phytoremediation. However, Mn interacts with other soil major and trace minerals. The interaction with phosphorus (P), a key element for plant nutrition and growth, has received less attention. In this study, we aimed to evaluate the effects of P sources (i.e. rock phosphate and monopotassium [KH2PO4]) and application rates on the P and Mn relationships in clay and sandy soils mixed with Mn-rich waste. Soils differing in texture were incubated for 60 days at room temperature (±20 °C), and changes in available P, Mn and soil pH were determined at 0, 30 and 60 days. The addition of Mn-rich solid waste significantly decreased available soil P in both soils with the greatest reduction of 62% and 52% from the sandy soil subjected to KH2PO4 and rock phosphate, respectively. In the clayey soil, the reduction was higher for the rock phosphate source implying more P was released from the rock phosphate in Mn-rich soils. This explanation was supported by the significant positive correlation between P and Mn for both soils when P is added in the form of rock phosphate. Our results suggest that Mn-rich waste is better in clay soils subjected to rock phosphate addition. Further research is needed to control Mn solid waste pollution levels in soils using specific crops with known phytoremediation properties.
Significance:
South African mining and smelting processes produce a lot of Mn-rich waste as a by-product that harms the environment if not appropriately managed. The efficient use of Mn-rich solid waste in agricultural soils is poorly studied; hence, this study focused on the role of soil type and Mn-rich waste addition on phosphorus release and availability
A correlation between the timing of skeletal maturity and dental development in black South African Patients
Full text linkThe growth potential of patients has a significant influence on the timing of orthodontic intervention and treatment modalities. Skeletal maturity and dental development are biological maturity indicators which can be used to determine the growth status of an individual.ObjectivesTo correlate the dental maturational stages of black South African individuals with the stages of skeletal maturation and to determine the diagnostic accuracy of using dental developmental stages to identify an individual’s skeletal maturity.DesignRetrospective, cross-sectional study.MethodsSkeletal maturity and dental development of 224 subjects were assessed using lateral cephalograms and panoramic radiographs, respectively. Statistical analyses included descriptive statistics, Spearman’s correlation coefficient and positive likelihood ratios (LHR).ResultsThe highest (rs =0.759, p<0.001) correlation with skeletalmaturity was identified for the second molar and the lowest correlation (rs=0.662, p<0.001) for the canine. Positive LHR>10 combined with sensitivity and specificity testing revealed that the second premolar (stage E), second molar (stage F) and second molar (stage H) have the most significant diagnostic reliability to identify the pre-pubertal, pubertal and post-pubertal growth phases, respectively. ConclusionDental development is a valuable diagnostic tool to assess skeletal maturation. The calcification of the second molar (stage F) is predictive of the pubertal growth phase
MUTILATION OF THE INDEPENDENCE OF THE JUDICIARY: THREATS, INTIMIDATION AND CONSTITUTIONAL AMENDMENTS IN ZIMBABWE
No full textZimbabwe adopted a new Constitution in 2013. It was widely believed that the new Constitution would deepen democracy and constitutionalism. Central to this was the establishment of an independent judiciary. Barely 10 years after the adoption of the Constitution, judicial independence has deteriorated. This has been the result of intimidation against the judiciary, and constitutional changes aimed at weakening the judiciary. This article is intended to show that there exists a long-term project to bring the judiciary under the control of the political arms in Zimbabwe. With a weakened judiciary, Zimbabwe loses the chance to entrench constitutionalism, democracy and the rule of law. The article first highlights the imperative of judicial independence, then examines how the judiciary has suffered from threats at the hands of politicians, and finally assesses the impact of two recent constitutional amendments on the independence of the judiciary. It is shown that the independence of the judiciary has been systematically mutilated, and that hopes for effective judicial review cardinal to constitutionalism have waned
Africa's Quest for Reform of the United Nations Security Council: A Just Cause Curbed by Unrealistic Proposals
Full text linkThe debate around viable global governance has become increasingly topical, particularly from the perspective of countries in the Global South. Concerning Africa, despite the continent's quest to reform the United Nations Security Council (UNSC), existing research has failed to comprehensively address the topic. Consequently, this article explores the arguments and challenges surrounding Africa's drive to secure a permanent voice in the UNSC. It argues that despite the enduring legacies of colonialism, neocolonial interventions, and being the primary concern of the UNSC agenda, Africa's claim for fair representation in the Council remains. The article attempts to address the research gap and contribute to the existing debate by examining why Africa has failed to be represented in the UNSC. Africa's collective initiative towards reforming the UN system is instrumental in ensuring inclusive and sustainable global governance. Nonetheless, Africa's insistence on immediate and full veto power for new entrants and its demand for representation merely through numbers inside the UN are unfeasible
Effect of water stratification and mixing on phytoplankton functional groups: a case study of Xikeng Reservoir, China
No full textA shift in reservoir stratification and mixing significantly affects the water column ecosystem, which in turn leads to changes in phytoplankton abundance and community structure. To explore the effects of stratification and mixing on the phytoplankton community structure of a diversion reservoir, a 1-year survey was divided into a stratification period in 2020, a mixing period in 2020, and a stratification period in 2021, and redundancy analysis (RDA), variance partitioning analysis (VPA) and Pearson correlation analysis were used to analyse the key drivers affecting the phytoplankton functional groups, using Xikeng Reservoir as a case study. During the study period, 8 phyla, 69 genera and 9 major functional groups were observed in this reservoir. The dominant functional groups varied significantly, being X1 in the stratified period in 2020; P and D in the mixing period in 2020; and D, X1, and M in the stratified period in 2021. The phytoplankton diversity index was greater in the mixing period than in the stratification period, in agreement with the results of the aquatic ecological status evaluation (Q index, higher in the mixing period than in the stratification period). However, phytoplankton diversity of Xikeng Reservoir was of limited value in assessing the degree of water pollution, so should be considered in combination with the Q index. Water temperature (WT), mixing depth (Zmix), nitrogen–phosphorus ratio (N/P), and total nitrogen (TN) were important drivers of phytoplankton functional group dynamics in different periods. The study provides a valuable reference for assessing the relationship between environmental factors and phytoplankton communities, as well as for the evaluation and conservation of aquatic ecosystems in southern China's water diversion reservoirs
The Operational Elements of the Vegetable Cooperatives: The Case of Agricultural Cooperative Societies in King Sabata Dalindyebo Local Municipality, Eastern Cape Province
No full textCooperatives are typically established to help create jobs and improve their members' economic and social conditions, among various other roles. Farmers’ cooperative societies play a vital role in enhancing the livelihood of resource-poor farmers. The government has initiated various support programmes to assist agricultural cooperative societies to remain viable; however, many cooperatives continue to flounder while some have collapsed. This study identifies operational components like members' roles, cooperative constitutions and decision-making processes, record-keeping, education and training of members, farm and financial management and level of extension service involvement as critical roles in sustaining agricultural cooperatives. Therefore, this study's objective was to assess the key operational components of vegetable cooperative societies and the level of extension support provided to the cooperatives in the study area. Ten functional vegetable cooperatives in the municipality were purposively selected for the study. At the same time, data for the survey was obtained from the board of directors and members of the cooperatives. Data was collected using semi-structured questionnaires consisting of closed and open-ended questions. The presentation of results was done using simple descriptive statistical tools. The study outcome shows that about 50% of the cooperatives noted that members were largely involved in the daily running of the cooperatives, governance, and decision-making processes. However, many cooperatives are constrained by the lack of training of its members on conflict resolutions (90%), with about 30% and 40% not receiving training on record keeping and financial management, respectively. The role of extension services towards the sustainability of the cooperatives is crucial. Most (80%) of the cooperatives indicated some level of interaction between the cooperatives and extension personnel, albeit the need to improve the frequency of extension visits, training, and follow-up appointments. The result of this study implies that cooperatives in the region need to improve in key operational areas. Extension personnel need to be more available to support cooperative activities effectively
Cost and Returns Analysis of Snail Production in Obio-Akpor Local Government Area, Rivers State, Nigeria
No full textThe study examined snail production cost and return analysis in Obio-Akpor Local Government Area of Rivers State, Nigeria. The study draws its essence from the fact that the supply of protein to the increasing population of Nigeria is inadequate. Given its profitability level, snail farming can serve as an important protein supplement to bridge the food insecurity gap. Through field surveys, copies of structured questionnaires were employed for collecting data from 40 snail farmers, who were randomly sampled. The analytical tools include frequencies, percentages, budgetary techniques, multiple regression, and mean scores. The results showed that snail farming was dominated by males (65%). The farmers were predominantly aged between 21 and 59, with a 67.5% score. Budgetary analysis showed that the farmers received a monthly net farm income of ₦113,000 (275.494 USD) and a gross margin of ₦1 345 000 (3279.11 USD), thus entailing the enterprise's profitability. Results of the multiple regression showed that variables like marital status and the purpose for farming were significant in determining the profitability status of snail farmers. Lack of collateral to secure loans to support farming and the problem of disease infected from contamination were some of the critical factors which constrained snail production, both jointly having a mean score of 3.35. It is recommended that the government give surety to registered farmers who do not have collateral to secure loans
The Legal Framework Governing Traditional Leaders' Role in Land Use Planning in South Africa
No full textThis article investigates the legal framework governing the role of traditional leaders in land use planning, through a historical gaze at the nature and authority of traditional leadership in South Africa. It is through this brief historical discussion that the influence of colonial and apartheid concepts of traditional leadership, as concretised in legislation, comes to the fore. This then creates a basis from which the Traditional and Khoisan Leadership Act 3 of 2019 and the Spatial Planning and Land Use Management Act 16 of 2013 are explored
Optimisation of adult Anopheles funestus blood-feeding on an artificial membrane feeding system
No full textMalaria is one of the most severe vector-borne diseases caused by Plasmodium parasites and transmitted by Anopheles mosquitoes. Laboratory-reared anophelines are essential to advance research needed to reduce or eliminate malaria. The success of laboratory rearing as well as studies on parasite-mosquito transmission, is advanced by using an artificial membrane feeding systems. These require the optimisation of mosquito feeding to ensure that an optimal number of mosquitoes feed, thereby enabling successful reproduction or research sample sizes. In this study, various parameters such as the type of artificial membrane, density of adults in the feeding cup, age of the mosquito, duration of starvation, method of starvation, the volume of blood meal, duration of feeding, feeding in the light or dark and the effect of lactic acid were evaluated to determine their impact on the feeding rate of a main African malaria vector, Anopheles funestus. By optimising the artificial membrane feeding parameters, an increase in the feeding rate of the An. funestus mosquitoes was observed. The results obtained from these parameters increased the feeding rate of An. funestus above 50%. However, feeding rates were not significantly increased by the type of membrane, mosquito density, the volume of blood meal, duration of feeding and the addition of lactic acid to the cattle intestine membrane. Therefore, this study provides information on suitable conditions for adult mosquito feeding that allows for successful laboratory rearing and colony maintenance. Furthermore, it provides additional information for research studies that are dependent on blood-feeding, such as transmission blocking studies, endectocide studies etc