Plants In South Africa Research Articles

Removal of helminth eggs by centralized and decentralized wastewater treatment plants in South Africa and Lesotho: health implications for direct and indirect exposure to the effluents

Wastewater may contain contaminants harmful to human health; hence, there is the need for treatment before discharge. Centralized wastewater treatment systems are the favored treatment options globally, but these are not necessarily superior in reduction of pathogens as compared to decentralized wastewater treatment systems (collectively called DEWATS). This study was therefore undertaken to assess the soil-transmitted helminth (STH) and Taenia sp. egg reduction efficiency of selected anaerobic baffled reactors and planted gravel filters compared to centralized wastewater treatment plants in South Africa and Lesotho. The risk of ascariasis with exposure to effluents from the centralized wastewater treatment plants was also assessed using the quantitative microbial risk assessment (QMRA) approach. Eggs of Ascaris spp., hookworm, Trichuris spp., Taenia spp., and Toxocara spp. were commonly detected in the untreated wastewater. The DEWATS plants removed between 95 and 100% of the STH and Taenia sp. eggs, with centralized plants removing between 67 and 100%. Helminth egg concentrations in the final effluents from the centralized wastewater treatment plants were consistently higher than those in the WHO recommended guideline (≤ 1 helminth egg/L) for agricultural use resulting in higher risk of ascariasis. Therefore, in conclusion, DEWATS plants may be more efficient in reducing the concentration of helminth eggs in wastewater, resulting in lower risks of STH infections upon exposure.

The Management of Invasive Alien Plants in South Africa: Strategy, Progress and Challenges

The Management of Invasive Alien Plants in South Africa: Strategy, Progress and Challenges

Trace metal enrichment observed in soils around a coal fired power plant in South Africa

A site assessment was conducted at a coal fired power plant in South Africa to determine whether surrounding soils were being enriched with trace metals resulting from activities at the power plant. It was found that deposition of fly ash from the flue stacks and the ash dump along with deposition of coal dust from the coal stock yard were the activities most likely to lead to such enrichment. Eighty topsoil samples were gathered and analysed for total metal content. Results were interpreted within the context of background values. It was found that concentrations of As, Cu, Mn, Ni and Pb exceeded local screening levels, but only As and Pb could be confidently attributed to anthropogenic intervention and actual enrichment.

Polysaccharides from the South African medicinal plant Artemisia afra: Structure and activity studies

Artemisia afra (Jacq. Ex. Willd), is an indigenous plant in South Africa and other parts of the African continent, where it is used as traditional medicine mostly for respiratory conditions. The objective of this study was to investigate the structural features of the polysaccharides from the leaves of this plant, as well as the biological activities of the polysaccharide fractions against the complement assay. Leaves of Artemisia afra were extracted sequentially with organic solvents (dichloromethane and methanol), 50% aqueous ethanol, and water at 50 and 100°C respectively. The polysaccharide extracts were fractionated by ion exchange chromatography and the resulting fractions were tested for biological activity against the complement fixation assay. Active fractions were further fractionated using gel filtration. Monosaccharide compositions and linkage analyses were determined for the relevant fractions. Polysaccharides were shown to be of the pectin type, and largely contain arabinogalactan, rhamnogalacturonan and homogalacturonan structural features. The presence of arabinogalactan type II features as suggested by methylation analysis was further confirmed by the ready precipitation of the relevant polysaccharides with the Yariv reagent. An unusual feature of some of these polysaccharides was the presence of relatively high levels of xylose as one of its monosaccharide constituents. Purified polysaccharide fractions were shown to possess higher biological activity than the selected standard in the complement assay. Digestion of these polysaccharides with an endo-polygalacturonase enzyme resulted in polymers with lower molecular weights as expected, but still with biological activity which exceeded that of the standard. Thus on the basis of these studies it may be suggested that immunomodulating properties probably contribute significantly to the health-promoting effects of this medicinal plant.

Occurrence of Cylindrocladium pauciramosum Causing Leaf Spot on Strelitzia reginae in Southern Brazil

Bird of paradise, also known as crane flower (Strelitzia reginae), is a monocotyledonous flowering native plant of South Africa. It is commonly grown and commercialized as an ornamental plant and is appreciated for its beautiful flowers (Luz et al., 2005). In September 2016, plants with severe spots on leaves were found in a commercial field (−31°48'S; −52°24'W) located in Pelotas, Rio Grande do Sul state, Brazil. The spots 0.1 to 2 cm in diameter on the leaves had a shape from circular to irregular with a light gray center and a dark gray to black border. Some leaf spots coalesced and, in severe cases, covered 50% of the of the leaf surface. Leaf lesion samples were surface sterilized (1% NaOCl solution for 1 min) and placed on potato dextrose agar (PDA). To identify the fungus responsible for those spots, a morphological analysis was carried out, and a molecular characterization was performed by amplifying and sequencing the internal transcribed spacer (ITS), β-tubulin (TUB2), calmodulin (CAL), translat...

The relationship between type of secondary education and subject choice with technically oriented aptitudes for automotive operators

Orientation: The central theme of this study attends to the role of secondary education in relation to two broad categories of specific aptitudes (psychomotor and spatial abilities). Utilising type of secondary education (incorporating subject choice) could be a crucial selection mechanism for high-volume, entry-level technical positions. Research purpose: The objective of this research was to investigate whether the type of secondary education (incorporating subject choice) could be used as a proxy for psychomotor (dexterity and coordination) and/or spatial (ability to mentally assemble representations and spatial perception 2-D and 3-D) aptitudes in the selection of operators for an automotive plant in South Africa. Motivation for the study: The motivation for this study arose from the evident gap in academic literature as well as the selection needs of the automotive industry. Research design, approach and method: A quantitative approach with a cross-sectional research design was used with a convenience sample ( n = 1566) of work-seeking applicants for automotive operator positions in South Africa. These applicants completed a biographical questionnaire and five sub-tests from the Trade Aptitude Test Battery. The Chi-square test was used to determine the association between form of Grade 12 qualification and selected technical aptitudes. Main findings: Statistically and practically significant relationships were found between type of secondary education (incorporating subject choice), eye–hand coordination and spatial visualisation. Broad performance levels in the five aptitude instruments employed in this study were significantly associated with the type of matriculation certificate held by applicants. Specifically, types of secondary education that included mathematics and/or science as subjects were associated with higher levels of performance in the five specific aptitudes. Practical/managerial implications: The type of secondary education (incorporating subject choice) held by applicants could be regarded as a key predictor variable in human resource selection. The study makes a case for a multiple-hurdles approach to selection and proposes a cost-effective preliminary screening method for low-level technical positions. Contribution/value-add: The study provides information to improve upon selection practices within the South African automotive industry. It could also assist human resource practitioners in designing selection processes for similar entry-level employees in other working contexts. The study makes a case for a multiple-hurdles approach to selection and highlights the reciprocal relationship between education and specific cognitive abilities in the science, technology, engineering and mathematics fields.

Comparative Early Life Stage Toxicity of the African Clawed Frog, Xenopus laevis Following Exposure to Selected Herbicide Formulations Applied to Eradicate Alien Plants in South Africa.

The rise in pesticides application has increased the need for better understanding of their ecological impacts. The global amphibian declines, for example, have been positively correlated with pesticides use. The differential susceptibility in the developmental stages of amphibians to chemical substances are still largely unknown. We examined the 96-h differential toxicity responses of embryos, premetamorphic and transitional larval stage of Xenopus laevis, to six formulated aquatic herbicide products containing the active ingredients of diquat dibromide (Midstream), glufosinate ammonium (Basta), imazapyr (Arsenal), and three glyphosate formulations (Roundup, Kilo Max, and Environ Glyphosate). The results showed the premetamorphic stage as the most sensitive to the herbicides toxicity. This study confirmed that the developmental stage at which amphibian are exposed to contaminants is critical to their survival and that the chemical contamination hypothesis of the global decline of amphibians should continue to be considered. This establishment of the premetamorphic larval as sensitive toxicity representative for all developmental stages of X. laevis means that this stage could be used more extensively in pesticides toxicity assessments.

Fusarium ear rot and fumonisins in maize kernels when comparing a Bt hybrid with its non-Bt isohybrid and under conventional insecticide control of Busseola fusca infestations

Maize production in South Africa is negatively affected by Fusarium verticillioides, an endophytic maize pathogen, as well as by Busseola fusca larval damage. Fusarium verticillioides causes ear, stem and root rot, and also produces fumonisin mycotoxins which are toxic to humans and livestock. The African stem borer (Busseola fusca) is a pest of economic importance in maize plants in South Africa. In this study, the interaction between F. verticillioides and B. fusca was investigated to elucidate its effects on Fusarium ear rot and fumonisin production in a Bt hybrid (MON810 event) and its B. fusca-susceptible non-Bt isohybrid. Field trials were conducted over three seasons using a randomised complete block design with six replicates per treatment. The effect of Beta-cyfluthrin (non-systemic, granular) and Benfuracarb (systemic, seed treatment) insecticide applications on the incidence of Fusarium ear rot and fumonisin production in maize was also determined in an unrelated conventional hybrid. For B. fusca infestations, larvae were dispensed into the whorl of each plant at the 12th leaf stage prior to tasselling, while a F. verticillioides MRC826 spore suspension was inoculated through the silks at the silking stage. Maize ears were harvested at physiological maturity and Fusarium ear rot, total fumonisin levels, stem borer damage and target DNA of fumonisin-producing Fusarium spp. quantified. Significantly less Fusarium ear rot and fumonisin were produced in the Bt maize hybrid compared to the non-Bt isohybrid under natural farming conditions, but fungal colonisation and fumonisin production under artificial F. verticillioides inoculation did not differ significantly between the Bt and non-Bt maize. Fumonisin production correlated moderately with the quantity of target DNA of fumonisin-producing Fusarium spp. extracted from maize plants. Benfuracarb application to control stem borer infestation resulted in a significant reduction in Fusarium ear rot and fumonisin production while Beta-cyfluthrin did not. Moreover, B. fusca damage to maize ears significantly increased when both insecticides were not applied to the B. fusca-infested plants. This study indicated that Bt maize and the application of Benfuracarb reduce B. fusca damage to maize ears thereby indirectly reducing Fusarium ear rot and fumonisin production. However, this was not consistent over seasons due to differences in climatic conditions.

Characteristics of selected non-woody invasive alien plants in South Africa and an evaluation of their potential for electricity generation

Alien invasive plants (AIPs) pose a threat to the existence of plant and animal biodiversity in the ecosystems they invade. They need to be cleared, monitored and eventually eradicated from the landscape. The potential and the economic viability to supply non-woody AIP biomass for electricity generation were assessed in this study, which was conducted on samples from 13 common non-woody AIPs in South Africa, namely: Arundo donax (giant reed), Lantana camara (lantana), Pontederia cordata (pickerel weed), Ricinus communis (castor-oil plant), Opuntia ficus-indica (sweet prickly pear), Solanum mauritianum (bugweed), Atriplex nummularia (saltbush), Cestrum laevigatum (inkberry), Senna didymobotrya (peanut butter cassia), Chromoleana odorata (chromoleana), Eichhornia crassipes (water hyacinth), Cerus jamacaru (queen of the night) and Agave sisilana (sisal plant). Proximate and ultimate analysis was made in order to assess the suitability of the biomass for different thermo-chemical conversion techniques for electricity generation. A financial evaluation of the costs to supply biomass to the plant gate was performed by combining the harvesting, chipping and transport costs. The results showed that the biomass of giant reed, lantana, bugweed, saltbush, inkberry, cassia and Chromoleana may be used to generate electricity through combustion, although the total average cost was approximately 50% higher than that of woody biomass feedstock, requiring a ‘fuel cost subsidy’ to justify their utilisation for energy production.

A power dispatch model for a ferrochrome plant heat recovery cogeneration system

A Organic Rankine Cycle waste heat recovery cogeneration system for heat recovery and power generation to relieve grid pressure and save energy cost for a ferrochrome smelting plant is investigated. Through the recovery and utilization of previously wasted heat from the facility’s internal smelting process off-gases, the cogeneration system is introduced to generate electrical power to supply the on-site electricity demand and feed electricity back to the utility grid when it is necessary and beneficial to do so. In addition, the cogeneration system generates cooling power through a lithium bromide-water solution absorption refrigeration cycle to meet the cooling requirements of the plant. The heat recovery process for power generation is modeled and the optimal power dispatching between the on-site loads and the utility grid is formulated as an economic power dispatching (EPD) problem, which aims to maximize the plant’s economic benefits by means of minimizing the cost of purchasing electricity from the utility and maximizing revenue from selling the generated electricity to the grid. Application of the developed model to a ferrochrome smelting plant in South Africa is presented as a case study. It is found that, for the studied case, more than $1,290,000 annual savings can be obtained as a result of the proposed heat recovery power generation system and the associated EPD model. In addition to this, more than $920,000 annual savings is obtained as a result of the generated cooling power via the proposed absorption refrigeration system. The combined cogeneration system is able to generate up to 4.4MW electrical power and 11.3MW cooling power from the recovered thermal energy that was previously wasted.

Prevalence of Bacillus in the interior tissues of Monsonia burkeana and other medicinal plants in South Africa

This study was undertaken to isolate and identify endophytic bacteria in Monsonia burkeana and eight other medicinal plant species, namely, Aloe aculeata, A. arborescens, A. chabaudii, Aloe spp., Athrixia phylicoides, Cotyledon orbiculata, Portulacaria afra and Sansevieria hyacinthoides. Interior tissues of the nine medicinal plant species were sampled and endophytic bacteria were isolated under sterile conditions. The bacteria were grown on Luria Bertani agar and bacterial species identification was done by using MALDI-TOF. A wide range of bacteria represented by the genera Acinetobacter, Anaerococcus, Arthrobacter, Bacillus, Burkholderia, Cellulosimicrobium, Clostridium, Enterobacter, Escherichia, Kocuria, Lactobacillus, Microbacterium, Pseudomonas, Staphylococcus, Streptomyces and Viridibacillus were identified in the different plant species. Bacillus was the most prevalent bacterial genus found in three plant genera and in all tissues of M. burkeana. This study forms the basis for further research in cataloguing endophytes in medicinal plants.

Clearing a Path Towards Effective Alien Invasive Control: the Legal Conundrum

Alien invasive plants pose significant ecological, social and economic challenges for South Africa. These species threaten South Africa’s rich biodiversity, deplete our scarce water resources, reduce the agricultural potential of land, cause soil erosion and intensify flooding and fires. According to recent estimations, over eight percent of land in South Africa has been invaded by these species and at current rates of expansion their impact could double in the next fifteen years. 
 
 In an attempt to curb the impending crises, the South African government has promulgated eleven national and various provincial laws which contain mechanisms for regulating the different threats posed by alien invasive plants. Certain of these laws are framework in nature while the majority are sectoral and aimed at regulating these species for one of the following four main purposes: biodiversity conservation; water conservation; agricultural management; and fire risk management. The responsibility for administering these laws spans four national departments, nine provincial environmental authorities, provincial conservation authorities, numerous local and statutory authorities. This fragmented regime, coupled with the adoption of a command and control approach to regulation, has proven inept in effectively regulating the spread of alien invasive plants in South Africa. This reality led the previous Minister of Environmental Affairs and Tourism, Mr Valli Moosa, to call for the development of a “coherent legislative framework … streamlined along the lines of the principles endorsed by the Convention on Biological Diversity”.
 
 This article critically analyses the government’s attempts to develop such a “coherent legislative framework” to regulate alien invasive plants in light of recent legislative reform. It is divided into two parts. Part one critically considers South Africa’s current laws of relevance to alien invasive plants with specific emphasis on their fragmented approach to planning and implementation. Part two provides suggestions on how the current legislative framework can be rationalised to entrench a more integrated, and hopefully successful, approach to the future regulation of alien invasive plants in South Africa. 

Micropropagation and secondary metabolites in Agathosma betulina (Berg.)

The global demand for medicinal plant products has increased in the last two decades leading to overexploitation and sometimes extinction of indigenous medicinal plants. Plant biotechnology offers an efficient approach to enhanced biosynthesis of essential and/or bioactive compounds in plants. This study was aimed at developing a micropropagation protocol for Agathosma betulina Berg. (Buchu), one of the most highly utilized aromatic medicinal plants in South Africa. The study also aimed to develop a technique that will enhance the biosynthesis of some bioactive compounds by manipulating the media composition. Seeds and nodal explants from Buchu were decontaminated, germinated and sub-cultured on Murashige and Skoog (1962) (MS) media adjusted with different concentrations of N6-Benzyladenine (BA), 1-naphthaleneacetic acid (NAA) and dichlorophenoxy acetic acid (2,4-D). Dried samples from in vitro cultures were extracted using dichloromethane and analyzed for phytochemical compositions using GC–MS. In vitro seed germination produced healthy seedlings that can be transplanted ex vitro. Significantly higher shoot proliferation was recorded in nodal explants grown in 1/2 strength MS supplemented with 2,4-D and a combination of NAA and BA. Phytochemical analysis revealed significantly higher amounts of limonene accumulated in callus compared to other plant parts. The most abundant phytochemicals were recorded in plants grown on media supplemented with NAA 2.7μM; these include limonene, pulegone and isomenthone (68, 39 and 33μgkg−1 DW respectively). Biosynthesis of certain compounds in in vitro culture of Buchu was induced by plant growth regulator application compared to the control. The plants possess a number of pharmacological properties including anticancer, antimicrobial and antioxidant. These activities are linked to inherent phytochemical contents. Hence, the use of micropropagation techniques that will enhance the biosynthesis of some bioactive compounds in Buchu will be an efficient means to meet the high demands for this plant.

Grasses as invasive plants in South Africa revisited: Patterns, pathways and management

Background: In many countries around the world, the most damaging invasive plant species are grasses. However, the status of grass invasions in South Africa has not been documented recently. Objectives: To update Sue Milton’s 2004 review of grasses as invasive alien plants in South Africa, provide the first detailed species level inventory of alien grasses in South Africa and assess the invasion dynamics and management of the group. Method: We compiled the most comprehensive inventory of alien grasses in South Africa to date using recorded occurrences of alien grasses in the country from various literature and database sources. Using historical literature, we reviewed past efforts to introduce alien grasses into South Africa. We sourced information on the origins, uses, distributions and minimum residence times to investigate pathways and patterns of spatial extent. We identified alien grasses in South Africa that are having environmental and economic impacts and determined whether management options have been identified, and legislation created, for these species. Results: There are at least 256 alien grass species in the country, 37 of which have become invasive. Alien grass species richness increased most dramatically from the late 1800s to about 1940. Alien grass species that are not naturalised or invasive have much shorter residence times than those that have naturalised or become invasive. Most grasses were probably introduced for forage purposes, and a large number of alien grass species were trialled at pasture research stations. A large number of alien grass species in South Africa are of Eurasian origin, although more recent introductions include species from elsewhere in Africa and from Australasia. Alien grasses are most prevalent in the south-west of the country, and the Fynbos Biome has the most alien grasses and the most widespread species. We identified 11 species that have recorded environmental and economic impacts in the country. Few alien grasses have prescribed or researched management techniques. Moreover, current legislation neither adequately covers invasive species nor reflects the impacts and geographical extent of these species. Conclusion: South Africa has few invasive grass species, but there is much uncertainty regarding the identity, numbers of species, distributions, abundances and impacts of alien grasses. Although introductions of alien grasses have declined in recent decades, South Africa has a potentially large invasion debt. This highlights the need for continued monitoring and much greater investment in alien grass management, research and legislation.

Assessing the status of biological control as a management tool for suppression of invasive alien plants in South Africa

Background: Biological control of invasive alien plants (IAPs) using introduced natural enemies contributes significantly to sustained, cost-effective management of natural resources in South Africa. The status of, and prospects for, biological control is therefore integral to National Status Reports (NSRs) on Biological Invasions, the first of which is due in 2017. Objectives: Our aim was to evaluate the status of, and prospects for, biological control of IAPs in South Africa. We discuss expansion of biological control and suggest indicators to be used in the upcoming NSR to assess sufficient growth. Method: We used published literature, unpublished work and personal communication to assess the status of biological control of IAPs. We propose indicators based on the targets for biological control that were proposed in the 2014 ‘National Strategy for dealing with biological invasions in South Africa’. To prioritise targets for future efforts, we used published lists of damaging IAPs and assessed the prospects for their biological control. Recommendations for using biological control as a management tool were made after discussion among the authors and with colleagues. Results: Significant control of several Cactaceae, Australian Acacia species and floating aquatic plants, and many other IAPs has been achieved in South Africa since 1913. Recently, biological control has benefited from improved international collaboration, a streamlined application process for the release of new biological control agents (resulting in the approval of 19 agents against 13 IAP species since 2013), and increased funding and capacity. There is still a need to improve implementation and to better integrate biological control with other control methods. In order to maximise benefits from biological control, increased investment is required, particularly in implementation and post-release evaluation, and in targeting new IAPs. Proposed targets for growth between 2017 and 2020 include an increase in financial investment in research by 29%, implementation by 28% and mass-rearing by 68%. Research capacity should increase by 29%, implementation capacity by 63% and mass-rearing capacity by 61%. New research projects should be initiated on 12 new IAP targets, while post-release monitoring efforts should be expanded to another 31 IAPs. Conclusion: Biological control of IAPs has contributed substantially to their management in South Africa, and continues to do so. Further investment in targeted aspects of IAP biological control will increase this contribution.

Changes in the composition and distribution of alien plants in South Africa: An update from the Southern African Plant Invaders Atlas

Background: Data on alien species status and occurrence are essential variables for the monitoring and reporting of biological invasions. The Southern African Plant Invaders Atlas (SAPIA) Project has, over the past 23 years, atlassed alien plants growing outside of cultivation. Objectives: To document changes in the alien plant taxa recorded in SAPIA, assess trends in invasive distributions and explore effects of management and regulations.Method: The numbers of alien plant taxa recorded were compared between May 2006 and May 2016, and changes in the extent of invasions at a quarter-degree squares (qds) scale were compared between 2000 and 2016. The effectiveness of regulations and interventions was assessed in terms of the relative change in the extent of invasions. Results: As of May 2016, SAPIA had records for 773 alien plant taxa, an increase of 172 since 2006. Between 2000 and 2016, the number of qds occupied by alien plants increased by ~50%, due both to ongoing sampling and to spread. Successful classical biological control programmes have reduced the rate of spread of some taxa and in a few cases have led to range contractions. However, other interventions had no detectable effect at a qds scale. Conclusions: South Africa has a growing number of invasive alien plant species across an increasing area. More taxa should be listed under national regulations, but ultimately more needs to be done to ensure that management is strategic and effective. SAPIA is a valuable tool for monitoring alien plant status and should be developed further so that invasions can be accurately tracked over time.

A preliminary assessment of the role of aquarium plant trade in the spread of non-native aquatic plants in South Africa: A DNA barcoding approach

A preliminary assessment of the role of aquarium plant trade in the spread of non-native aquatic plants in South Africa: A DNA barcoding approach

Comparing the flow dynamics and particle settling in full-scale sedimentation tanks of different lengths

The efficiency of sedimentation is dependent on settling tank design and operation, where the streamlined solid–liquid separation results in water of safe potable quality. It is therefore important that the tank design and operation are sufficiently optimised. Sedimentation tanks are commonly overdesigned, leading to unwarranted capital expenditure, and overloading. This study used computational fluid dynamics to model the current conditions of two full-scale sedimentation tanks of different lengths at a large drinking water treatment plant in South Africa, using the shear stress transport turbulence model. The flow dynamics and the polyelectrolyte flocculated particle settling efficiency between the short tank and the long tank were compared. Recirculation zones near the inlet were pronounced in the short tank, which resulted in particles being drawn towards the outlets. The flow in the long tank isolated the inlet and outlet, with low particle volume fractions and particle velocities at the weirs. The particle removal in both tanks was greater than 99%; however, removal was higher in the long tank (99.86%), hence it was more efficient despite greater infrastructure cost. Computational fluid dynamics modelling is a tremendous operational tool which can review the performance of alternative tank designs and provide valuable input into future design.

Variation in essential oil composition of Leonotis leonurus, an important medicinal plant in South Africa

Leonotis leonurus widely used by traditional healers in southern Africa for treatment of various ailments, is well known for its reported psychoactive properties. The present study was undertaken to investigate the variation in essential oil composition between geographically distinct populations of L. leonurus in South Africa using gas chromatography. Plant material (n = 50) was collected from three provinces of South Africa. Essential oils of the aerial parts were obtained by hydrodistillation and analysed using one and two dimensional gas chromatography. Twenty-six compounds accounted for more than 80% of the total composition of the oil. Eight major constituents in the oil, representing about 50% of the total oil composition, were identified by both GC–MS–FID and GCxGC–ToF–MS. These major compounds were trans-β-ocimene (0.1–5.0%), cis-β-ocimene (0.1–31.5%), β-caryophyllene (0.3–15.0%), caryophyllene oxide (0.1–5.0%), α-humulene (0.4–18.2%), γ-elemene (0.4–10.6%), α-cubebene (0.2–12.0%) and germacrene D (0.1–22.1%). Marked similarities exist in the essential oil composition between populations; differences are mostly quantitative when determined by GC–MS–FID, while GCxGC–ToF–MS data reveals both quantitative and qualitative differences.Untargeted multivariate analysis was performed using SIMCA-P + 14.0 PCA and OPLS-DA methods, identifying two distinct clusters, inland and coastal populations.

Removal of aluminium and iron from surface water by conventional water treatment

Detailed source water monitoring showed large variations in the total concentrations of aluminium and iron in the Vaal Dam, South Africa, which were highlighted as a specific concern for one of the largest drinking water treatment plants in South Africa. This study aimed to better understand the presence of these metals in the source water, removal of these metals through the conventional treatment process, and final water quality trends, for the period 2008 to 2014. Aluminium and iron concentrations were highly variable and showed significant influence on colour and turbidity in source water. Sedimentation performed well, and removed over 70% of the metal concentration from the raw water. Filtration removed 15% of the remaining aluminium and iron concentrations. The pH and turbidity of the final water had minor effects on the metal concentration in the final water. The conventional treatment process was shown to be capable of removing aluminium and iron from the source water as both were within water quality limits in the final water. This study highlighted the importance of source water quality monitoring and treatment plant efficacy in evaluating whether the current treatment technology is appropriate for current and future challenges.