Evaluation of mercury accumulation and biotransportation in wetland plants affected by gold mining and industrial activities

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science, 2017Six different plant species that grow in a natural wetland impacted by old gold mining and other industrial activities were randomly selected with surface sediments. These included: Cyperus eragrostis (Nutgrass), Datura stramonium (Jimson weed), Melilotus alba (White sweetclover), Panicum coloratum (Blue panicgrass), Persicaria lapathifolia (Pale smartweed) and Phragmites australis (Common reed). These were used to investigate the levels of mercury in the wet and dry seasons, as well as to evaluate which of the species could be utilized for the remediation of mercury contaminated areas. The results obtained indicated that metal contamination could be determined from sediments and plant tissues. The pH values of the sediment samples were mostly neutral to slightly acidic and the redox potential was high in the wet season. On the other hand the dry season was characterised by very acidic and moderately oxidizing conditions. In summer all six plant species had higher concentration of HgT in sediments, whereas in winter the levels of HgT were elevated in the aerial tissues of the plants. The mercury accumulation patterns differed according to individual plant species and seasonality. Seasonal differences were significant but generally the MeHg concentrations in the wet season were higher in both surface sediments and plant tissues. Mercury methylation differed between species but concentration of MeHg was in general higher in plants with high concentration of mercury in sediments. The conversion of bioavailable HgT seemed more pronounced in tissues of the plants sampled in the wet season unlike those sampled in the dry season. Generally bioaccumulation factors were less than 1 in both the wet and dry seasons for all the plant species indicating that Hg was mainly retained in sediments. The translocation factor values were greater than 1 meaning metals were accumulated fundamentally in aboveground tissues for the plants D. stramonium, P. lapathifolia, P. coloratum and C. eragrostis in both the wet and dry seasons. The small bioaccumulation factors combined with translocation factor values greater than 1 were an indication that mercury present in the sediments was not the only source of mercury for the plant species growing in a contaminated environment. For P. australis the translocation of mercury was heavily influenced by seasonality, however this was not the case with M. alba. All the selected plant species demonstrated the capacity to grow in a heavily contaminated area, where P. australis and M. alba seemed to have developed an exclusion strategy to deal with toxic heavy metals therefore suitable for phytostabilisation. D. stramonium, P. lapathifolia, P. coloratum and C. eragrostis on the other hand exhibited characteristics of plants that can be successfully used for phytoextraction and phytovolatilization.XL201

Pesticides and the agricultural chemicals industry association

A report on the pesticides manufacturing Industry in Zimbabwe.The Agricultural Chemicals Industry Association (ACIA) represents the manufacturers and distributors of agrochemicals and animal health products in Zimbabwe. ACIA is also a member of the International Group of National Associations of Agrochemical Manufacturers (GIFAP). Through GIFAP, ACIA has endorsed the Food and Agriculture Organization’s Code of Conduct on the distribution and use of agrochemicals. Members of ACIA are expected to adhere to the legislation and regulations governing the proper use of agrochemicals as stipulated by the Department of Research and Specialist Services and the Drugs Control,Council. ACIA also assists in implementing the Code of Conduct on the distribution and use of agrochemicals by training farmers and workers on the proper and safe handling of agrochemicals. Knowledge of the probable health effects of agrochemicals is also a concern ol ACIA

Frustrated order on extrinsic geometries

We study, analytically and theoretically, defects in a nematically-ordered surface that couple to the extrinsic geometry of a surface. Though the intrinsic geometry tends to confine topological defects to regions of large Gaussian curvature, extrinsic couplings tend to orient the nematic in the local direction of maximum or minimum bending. This additional frustration is unavoidable and most important on surfaces of negative Gaussian curvature, where it leads to a complex ground state thermodynamics. We show, in contradistinction to the well-known effects of intrinsic geometry, that extrinsic curvature expels disclinations from the region of maximum curvature above a critical coupling threshold. On catenoids lacking an "inside-outside" symmetry, defects are expelled altogether.Comment: 4 pages, 3 figure

The learning process of access trainees : an investigation of study motives and strategies : a research report presented in partial fulfilment of the requirements for the degree of Master of Business Studies at Massey University

The study applied Biggs' Study Process Questionnaire to the context of transition education in an investigation of the approaches, motivations to learn and strategies trainees in Access Training Scheme used in their learning. Respondents were also asked information about their age. sex, educational qualification, ethnic origin and how long they had been without a job. Three training centres in Palmerston North city were chosen.The first centre conducted a course in drama, the second, a course in Maori language and culture, and the third, a course in basic computer skills. The Study Process Questionnaire was administered to 33 subjects, 16 males and 17 females. The Study Process Questionnaire is concerned with three main approaches to studying and their three associated motivations and strategies. Surface Appproach is dominated by extrinsic motivations where a learner concern is with obtaining a qualification. The study strategy involves memorising and reproducing when required in a test. Deep Approach is linked to intrinsic motivation dominated by intrinsic interest in the subject or task. Students under this motivation tend to search for meaningful learning and read widely. Achievement Approach is governed by achievement motivation and is associated with a desire to compete and obtain higher grades. Learners predisposed to this approach tend to schedule their time and do homeworks. Trainees studied to express the use of Deep Approach more than Surface or Achievement Approaches. Accordingly they were inclined to be deep motivated and predisposed to adopt deep strategy to surface or achievement strategy in their study. A follow-up interview with 11 trainees tended to confirm the findings of the Study Process Questionnaire. It was concluded that the Access trainees in the sample were likely to adopt deep approach in their study. This suggests that they are inclined to be intrinsically motivated in their learning and may be predisposed to engage in meaningful learning

Privatization of urban public spaces and its impact on sustainable cities and social inclusion

Abstract: The privatization of urban public spaces (UPS) raises questions about the sustainability of urban settings and the impact that privatization has on social inclusion and access to urban land and well developed public spaces. This paper reports and discusses findings from a critical review of local and international literature on the privatization of UPS. Although cities partner with the private sector in the planning, development, maintenance and management of UPS in attempt to build socially cohesive, environmentally friendly, and economically competitive cities, the review findings reveal that privatization is associated with the decreasing ‘publicness’ of UPS and shortcomings in the fulfilment of social and political responsibilities. Some of these shortcomings are the result of cities using privatization as a vehicle for economic development and financial revenue and not necessarily incorporating all sustainability attributes in terms of city planning and development. This paper argues that local authorities, city planning decision makers and the interests they are pursuing, influence the sustainable and socially cohesive design of cities

Anchoring bias, idiosyncratic volatility and the cross-section of stock returns

Ang, Hodrick, Xing and Zhang (2006) document an anomaly in the cross-section of stock returns. They show that high idiosyncratic volatility (IVOL) firms earn lower returns in the following month. Specifically, they find after sorting stocks in quintile portfolios based on the previous month\u27s IVOL that a zero-investment portfolio long the most volatile quintile of stocks and short the least yields about -1% during the subsequent month. The evidence reported in Ang, Hodrick, Xing and Zhang (2006) is primarily puzzling because traditional asset pricing theories suggest that (i) only systematic risk should be priced, (ii) to the extent that markets are complete, frictionless with well diversified investors, idiosyncratic volatility should not matter, and (iii) for incomplete markets with under-diversified investors, idiosyncratic volatility should be positively priced (See Merton (1987)). In my dissertation, I test the implications of both the anchoring bias and investor sentiments for the idiosyncratic volatility puzzle. I posit that subjecting market participants to such behavioral biases can go a long way in helping us understand this puzzling volatility-return relationship for which the recent empirical evidence is mixed. I consider in this study the possibility that investors are affected by anchoring bias. Employing George and Hwang (2004) measure of Nearness to 52-week high, I form and investigate the two primary hypotheses. If market participants do anchor on the 52-week high and stocks for which bad news recently reached the market are overpriced (as shown by George and Hwang (2004)) and idiosyncratic volatility is seen as a proxy for uncertainty (Johnson (2004)), short-sale constraints (Nagel (2005) and George and Hwang (2011)) or arbitrage risk (Ali, Hwang and Trombley (2003), then I should expect the negative relationship between idiosyncratic volatility and stock returns to be stronger for stocks that are the farther away from their 52-week high price. Further, I note that Veronesi (1999) proposes a model of overreaction to bad news in good times. He argues and shows that in good times, bad news signals increased uncertainty and greater likelihood negative future performance, both of which lower stock prices and lead to negative returns. I therefore hypothesize that the IVOL puzzle should be stronger when bad news reaches the market in good times. I report robust empirical evidence consistent with my hypotheses using U.S data from 1965 to 2012. I first investigate the presence of the IVOL puzzle in my sample using a portfolio sorting approach. I find that the choice of data frequency to estimate idiosyncratic volatility, weighing scheme and breakpoints all play an important role in the relationship between IVOL and future returns. After investigating whether anchoring on the 52-week high can explain the IVOL puzzle, I find a strong and robust negative relationship between IVOL and future returns for stocks that are away from their 52-week high. In addition, I also find that my previous results persist up to six months following portfolio formation. I also document that there exist, for stocks that are far from their 52-week high, an even stronger negative volatility-return relationship in period where investors sentiments are at their highest. That is, the negative relationship between IVOL and future returns is even stronger when bad news reaches the market in good times. The evidence I present appear to be consistent with the notion that investors are affected by anchoring bias, a behavior that contributes to the overpricing of stocks that move away from their 52-week high prices as shown by George and Hwang (2004). My results are further consistent with the views in the finance literature suggesting that idiosyncratic volatility could serve as a proxy for uncertainty (See Johnson (2004)), short-sale constraints (See Nagel (2005) and George and Hwang (2011)) or arbitrage risk (See Ali, Hwang and Trombley (2003)). Moreover, I find that all my results are even stronger with the arrival of bad news in good times; a piece of evidence consistent with the proposition of Veronesi (1999). Finally, all these results cannot be explained by other known risk factors, momentum, book-to-market, as well as the January effect

Exploring Project Complexity Relations to Scope Changes in Construction Projects: A Case Study of NEC Projects in South Africa

Construction projects are of very complex nature, and subject to circumstances of high uncertainties and risks due to the interdependences of activities and processes in the project performance.  As a result of the dynamic complexities inherited in construction projects, changes in the scope of work are inevitable. Of particular concern is that, when scope changes are introduced in a project, contractors follow a systematic procedure in managing the changes, but with poor planning and implementation thereof because the project complexities that underpin the scope changes are not fully understood. Therefore, despite that complexity is an inherent and defining feature of construction projects, studies in the literature have failed to grasp and present the dynamics of project complexity which underlie the scope changes in the delivery of construction project. The TOE (Technical Organizational Environmental) framework was adopted and applied on a multiple-case study research design in order to explore and denote project complexity relations to scope changes in construction projects. Through a content analysis procedure, six key elements of project complexities that relate to scope changes in the construction projects has emerged. Understanding these complexity elements could enable the project management team to apply a front-end planning approach in the initiation phase of the projects in order to better manage scope changes in the execution phase of the project, and eventually to improve the project performance