The effects of sublethal additions of mercuric chloride were studied in the marine diatom Skaletonema costatug (Grev.) Cleve grown in ammonium-limited chemostats and batch cultures. In the short-term Hg exposure (up to 5 hours), unexposed chemostat effluents were simultaneously perturbed with 5 μM NH₄Cl and Hg concentrations ranging from 0.04 to 5.53 nM HgCl₂. In the long-term Hg exposure (679. 5 hours), ammonium-starved effluents were only perturbed with 5 μM NH₄Cl. In the short-term Hg exposure, when the effluent from the chemostat culture was starved for 1.5 hours, Hg decreased the affinity for the substrate (increased Ks value) and the rate of ammonium assimilation or the internally controlled uptake rate, Vimax . When the effluent was starved for 30 hours, only Vimax was reduced. These effects occurred between 1.84 and 3,68, and at 0,18 nM HgCl₂ in effluents starved for 1.5 and 30 hours, respectively. The maximum rate of uptake, Vs, was not depressed. In the long-term Hg exposure, at least 0.37 nH HgCl₂ decreased the specific growth rate and the maximum cell density, while the chlorophyll a per cell increased. A period of population decline was followed by resumption of growth. Morphological alterations were observed before and after the recovery. In the long-term experiment, six days of continual exposure to 0.37 nM HgCl₂ gradually increased the Ks value without affecting Vs and Vimax. The results from exposure to 3.68 nM HgCl₂ were similar to the short-term Hg exposure, since both the substrate affinity (Ks value) and the assimilatory rate Vimax were impaired. In addition, the maximal uptake rate, Vs, was also reduced after exposure to 3.68 nM HgCl₂ for six days in the long-term experiment. After resumption of growth in the Hg-treated cultures, when a new steady-state was established, the affinity for the substrate and assimilatory rates increased in phase D (day 23) compared to phase A (day 6). The recovery of growth and nutrient uptake rates in phase D, may have been partially mediated by the acquisition of Hg tolerance and the appearance of cells of a different stage of the sexual life cycle, as suggested by differences in cell size and chemical composition. An attempt was made to determine whether a short-term physiological response (Hg induction of metallothionein synthesis) could be responsible for the recovery. The 250 nm absorbance profile, of nutrient-saturated cultures exposed for 90 to 116 hours to sublethal concentrations of mercury, showed no large absorbance peak in the medium molecular weight pool, corresponding to laetallothionein, as it occurs in animals exposed to heavy metals. The intracellular distribution and levels of Cu, Zn, and Hg in S. costatum, grown in nutrient-saturated batch cultures, were affected by 0.37 nM HgCl₂. A concentration equal to or greater than 1.84 nM HgCl₂ reduced the growth rate and cell density, possibly due to the accumulation of Hg in the high m.w. pool. Exposure to 1.84 nM HgCl₂ prior to a second addition of 5.53 nM reduced Hg levels in ths high m.w. pool. Upon Hg exposure, Zn levels decreased in the high and low m.w. fractions but gradually increased in the medium m.w. pool. Copper slightly increased in the high m.w. pool but remained constant in the medium and low m.w. pools, in relation to total intracellular levels. High levels of Cu and Zn in the low m.w. pool suggests that a substance of a lower m.w., than usually reported for metallothionein, may be involved in the storage and detoxification of heavy metals in S. costatum. / Science, Faculty of / Botany, Department of / Graduate

Bibliography: pages 136-145. / The aim of this report is to develop a procedure for the environmental evaluation of roads in South Africa, because in the past the environmental evaluation of road projects have been on an ad hoc basis, often using different formats. The procedure is therefore to be replicable from scheme to scheme, procedure, Management and is to be incorporated into the existing road development while drawing on the principles of Integrated Environmental The first part of the report is a study of the environmental evaluation procedures adopted in the United Kingdom, United States of America and Ontario (Canada). The environmental evaluation of roads in these countries are compared under the following headings: contextual features of the environmental evaluation procedures; the planning, location and design stages of the environmental evaluation procedures, and the environmental evaluation documentation. In this comparative study, the common and unique steps and elements are identified in order to generate an 'Ideal'. The second part of the report is a study on the environmental evaluation of roads in South Africa. The administrative structure, legislation, policy and planning procedures for roads in South Africa, and Integrated Environmental Management (IEM) are discussed. Although IEM is currently been developed and road authorities are committed to IEM, the procedure still needs to be incorporated into the existing road development procedure. The third part of the report develops a procedure for the environmental evaluation of roads in South Africa. The procedure developed incorporates common and unique steps and elements generated in the 'Ideal' into the existing road development procedure. The Environmental Conservation Act and Integrated Environmental Management are also taken into account in developing the procedure. Finally, as there is at present no formal documented procedure for the environmental evaluation of roads in South Africa, it is recommended that the procedure be considered by road and environmental authorities with a view to implementing it.

本研究以计划行为理论、态度情境行为理论、制度理论为基础，从社会心理学出发，对个体基于心理反应过程的低碳消费行为及其情境因素进行了研究。通过实证研究发现，低碳消费态度和低碳消费主观规范对低碳消费行为的影响是通过低碳消费意向实现的。低碳消费意向在低碳消费态度和低碳主观规范与低碳消费行为的关系构建中起到中介效应。结果表明，低碳消费态度和低碳消费主观规范均与低碳行为意向之间显著正相关，低碳行为意向和低碳消费行为之间显著正相关。低碳消费意向是低碳消费态度和低碳消费行为的部分中介，低碳消费意向还是低碳消费主观规范和低碳消费行为的完全中介。同时，本研究也发现便利条件对低碳消费意向和低碳消费行为之间的关系起正向调节作用。Based on the Theory of Planned Behavior, Attitude-Context-Behavior Theory and Institutional Theory, this study explores low-carbon consumption behavior based on Psychological reaction process and its context factors from the perspective of social psychology.Empirical research shows that Low Carbon Consumption Attitudes(LCCA) and Low Carbon Consumption Subjective Norms(LCCSN) influence Low Carbon Consumption Behavior(LCCB) through Low Carbon Consumption Intention(LCCI). The results show that both LCCA and LCCSN have significant positive correlations with LCCI, and LCCI has significant positive correlations with LCCB. LCCI is partial mediation between LCCA and LCCB , LCCI is also complete mediation between LCCSN and LCCB. Meanwhile, this article infer that facilitating conditions have moderating effects which strengthen the positive relationship between LCCSN and LCCI.

Includes bibliography. / Recreation has an important social function in modern societies, with ever-increasing pressures in the day-to-day life being felt by most people. This study addresses the impact of recreational activity on metropolitan shorelines, with particular reference to the False Bay shoreline. During summer holiday periods shoreline utilization in the Western Cape peaks on the public holidays of 26 December, 1 and 2 January, beach attendances reaching levels of 2 to 10 times higher than attendances on other days during the summer holidays. The greatest proportion of visitors to the beach (94%) engage in non-exploitative activities, such as sunbathing and swimming. Most visitors occur on the beaches between 12h00 and 16h00, week-ends being most popular during out-of-season periods, but in-season week day attendances exceed those of weekends. Only 6% of visitors surveyed were engaged in exploitative activities such as angling and bait- or food-gathering. Conservation awareness of visitors to the shore is related to the place of residence of the person, as well as activity engaged in by the person. Fish numbers and their size frequency distributions in protected areas differs to those of unprotected areas. If boulders on a sheltered shore are over-turned during bait gathering it has an adverse effect on the boulder communities, whether the boulders are replaced or left over-turned. When bait gatherers target on mussel-worms as bait, they may cause inadvertent damage to the primary matrix of mussel bed or tube-worm reef in the process, thereby affecting ecological succession processes in the intertidal environment. Management of metropolitan shorelines must therefore provide for quality recreational experiences, while applying conservation measures to selected areas that are susceptible to over-exploitation under the onslaught of ever-increasing numbers of recreationists. For such measures to be of any benefit to the marine environment, it is essential that people are not only informed, but that the regulations are also properly enforced.

A dissertation submitted in ful lment of the requirements for the degree of Masters of Science in the School of Computational and Applied Mathematics , University of the Witwatersrand, Johannesburg, July 2018 / The mining industry forms an integral part of South Africa - its society, culture, history and of course, its economy. This research dissertation focuses on the Open Pit Mine Production Scheduling Problem, a cornerstone in the design and planning of an open pit mining venture and its pro tability thereafter. The accompanying optimisation problem is usually both complex and large. We investigate existing initial solutions as well as two existing metaheuristic algorithms that have been used to solve this problem, improving upon them and introducing a pseudo greedy approach that seeks production schedule improvement in the immediate solution space neighbourhood. This addition greatly improves initial solutions to the problem. Through analysis on a smaller and larger mining instance we reveal the perceived advantages and disadvantages of two existing metaheuristics in producing optimal production schedules. We then propose a parent algorithm that interchangeably selects either of these algorithms based on probabilities determined by their observed performances during computation periods. The parent algorithm produces a strong production schedule that surpasses the current best found solution for the larger mining instance. With these ndings we propose a probabilistic selection method parent algorithm that interchanges between both algorithms in an e ort to achieve a better solution. / E.R. 2019

A research report submitted to the Faculty of Science, in partial fulfilment of the requirements for the degree of Master of Science (Geographical Information Systems and Remote Sensing) at the School of Geography, Archaeology & Environmental Studies, University of the Witwatersrand. Johannesburg. 23 March 2017. / The main purpose of this research was to investigate the impact of open pit mining on the Land Use Land Cover Change (LULCC) of the Yatela region in Mali. The methodology used to assess the open pit mining operations were remote sensing vegetation indices (NDVI) and LULC maps at a four year interval from 1999 to 2015. The Support Vector Machine (SVM) classification was used to create the LULC maps. Assessment of the quality from SVM classification outputs were analyzed using the confusion matrix technique. Three satellites (Landsat 5, 7 and 8) were used to analyze the images that were extracted from scene path 202 row 050. The NDVI results were able to detect the development and expenditure of the open pit mine in the Yatela region from 1999 to 2015. The roads and open pit mine area were easily detected from the 1999 NDVI results. Over the years the vegetation cover varied in the Yatela region, good vegetation cover was present before mine operations (1999) and after the mine closure (2015). The average overall accuracy for the five classified images was 84.31%. The change detection statistics showed that there were significant changes in each of the five classes over the 16 year period. Anthropogenic factors are assumed to be the major contributing factor to the Land Use Land Cover Change in the Yatela region. Nonetheless, this should not mean that climate factors can be neglected as contributing factors to LULCC in the region. Due to data limitation this research was unable to test any climatic influences. / LG2018

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