Environmental implications of phytoextraction for mercury and gold : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science

The overall objective of this study was to investigate how plants could be used to harvest gold (phytomining) and at the same time remove mercury (phytoremediation) from auriferous mercury-contaminated soils. This study was undertaken to find appropriate plants that could be used to harvest gold, residual in mine tailings or in uneconomic low-grade ore, and at the same time remove residual mercury, commonly used to extract the gold in artisanal mining areas. Different procedures involving analytical methodology, leaching of acid mine tailings and the growing of plants in both gold and mercury-bearing substrates were undertaken. The analytical methods involved in the analysis of gold in the laboratory using the modern instruments were Flame Atomic Absorption Spectrometry (FAAS) and Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The determination of mercury involved using Flameless Atomic Absorption Spectrometry. To understand the induced solubility of metals in phytoextraction, Tui mine tailings were leached with several chemicals known to solubilise gold: ammonium thiocyanate, ammonium thiosulphate and urea. The pH of the tailings material was varied through amendment with lime to examine the effect of this geochemical parameter on metal solubility and thus the potential for both plant uptake and leaching. The Tui mine tailings were chosen because of their geochemistry; these are highly weathered sulphide-ore tailings that leach heavy metals into adjacent water systems. The induced-phytoextraction potential of root crops was also examined in this thesis. Five root crops were grown in an artificial substrate consisting of 3.8 mg/kg (ppm) of elemental gold dispersed in sand. The possibility of using these root crops for phytomining was determined by separately adding chelating agents ammonium thiocyanate and ammonium thiosulphate to the substrate. In most cases there was a higher gold concentration in the roots than in the shoots. The highest mean gold concentrations were found in carrot roots and in roots of two radish cultivars. It was concluded that there was some potential for the use of carrot to grow an economic crop of gold from mine tailings. Results obtained from experiments where plants were grown in Tui tailings indicated that both chicory and Brassica juncea could be used for the phytoextraction of gold and mercury in the same crop. Under acidic conditions thiocyanate induced the uptake of gold by Brassica juncea and the uptake of mercury by chicory; and thiosulphate induced the uptake of mercury by chicory, but it did not induce the uptake of gold by the same plant. Under alkaline conditions, treatment with ammonium thiosulphate induced the uptake of gold and mercury by Brassica juncea; and treatment with thiosulphate induced the uptake of mercury by chicory but it did not induce the uptake of gold. It was therefore concluded that, Brassica juncea could be used for phytoextraction of gold and mercury when ammonium thiosulphate is applied to the substrate. Results from the root-crop experiment indicate that, carrots could supersede most of the plants used due to the greater apparent metal-uptake potential. Finally, a model is proposed for field trials to examine the potential of phytoextraction for gold and mercury in Tanzania. The aim of this model is to examine how the positive results obtained from research conducted in the laboratory and greenhouse can be put into practice. The use of similar plants as well as traditional tropical species (e.g. wild cassava - a known accumulator of cyanide) is suggested along with suitable chemical amendments

Determinants of Choice of Institutional Marketing Arrangements by Small Poultry Businesses in Tanzania: Application of Transaction Cost Theory

The transaction cost (TC) theory of the firm provides a conceptual model suitable for investigating the mechanism by which business firms evolve and grow. This paper uses poultry farm businesses (PFBs) in Tanzania as a vehicle of assessing relevance of the theory in explaining factors determining choice of institutional arrangement, for the purpose of identifying policy measures that can influence small business firms to opt for contractual businesses. A cross-sectional survey was conducted in two regions in the country covering 170 respondents. Logistic regression analysis indicate that the choice by business firms to opt for a particular institutional arrangement is determined by all the components of total transaction cost (TTC); as all were statistically significant (P < 0.05). It shows also that search and screening cost has greatest impact on choice of institutional arrangement (Wald = 8.745) followed by enforcement cost (Wald = 4.735) and negotiation cost (Wald = 4.735). It indicates in addition that, probability of PFBs to enter into contractual businesses falls with increase in Transaction Costs (TCs). Linear regression analysis shows, in addition that, search and screening cost has greatest elasticity to TTC (Beta = 0.596), followed by enforcement cost (Beta = 0.43) and negotiation cost (Beta =0.437). A theory based intervention should therefore, mainly be focused on reducing search and screening cost, followed by the other components of TTC.Keywords: Transaction costs, poultry farm businesses, institutional arrangement

Institutional Overlap and Power Relations in Private-Led Regularization Projects in Informal Settlements: The case of Gairo Town, Morogoro

In the early 1990s to date, the private sector has continued to gain momentum in urban planning and service delivery. Among others, the penetration of neo-liberal ideology in policies and legislations empowered the engagement of private sector in urban planning domain. Subsequently many private firms have dominated the process of the preparation of details schemes including regularization of informal settlements in different cities, municipalities and towns in Tanzania. However, the institutional overlap and power relation and approach used by the private sector at the grassroot levels to mobilize resources to meet the cost of regularization of informal settlements are rarely documented and discussed. This paper uses the case of Gairo Town regularization project to illuminate on the existing institutions, actors and power relation in the private-lead regularization projects and approach used to engage the community in financing the preparation of regularization schemes. Through household surveys, official and key informant interviews, observations and mapping, steps followed by the private firms to acquire the projects from the Planning Authority to the community levels were documented and analyzed. The findings show that when there are mutually beneficial interactions among private sector, politicians and grassroots institutions, the community contributes their financial resources to prepare regularization schemes of their settlements. The institutional overlap in terms of multiple allocation of actors in different institutional levels and power relations facilitate the resource mobilization for regularization projects in the informal settlements.

Teachers’ In-service Training on ICT: Prospects and Challenges: A Case of Bariadi District.

This study investigated the challenges and prospects of teachers’ in-service training in Bariadi district. This end was fulfilled by descriptive study design, which is mostly appropriate for social sciences research employing qualitative as a major approach to the study, as well as quantitative approach to collect and analyze data in order to address the main objective of the study. A sample of 62 teachers and 20 students was purposefully and randomly selected from 20 secondary schools. The objectives guided this study were: to explore teachers’ opinions on the benefits of using ICT in teaching, to investigate the availability of ICT in-service training and facilities to assist teaching-learning in schools and to explore the limitations that hinder teachers from using ICT. The findings of the study revealed that, the use of ICT in teaching processes has benefits to teachers and learners in the entire process of teaching and learning. In addition, there is inadequate teachers’ in-service training on ICT and lack of enough technical support as well as limited ICT facilities in schools. The study recommends that, teachers should be trained on how to use ICT in teaching, should develop positive attitude towards ICT use and the Ministry of Education and Vocational Training has to provide more funds to establish ICT facilities that will enable schools to attain infrastructures for teaching and learning process. In this study therefore, teachers’ in-service training on ICT is seen as the solution to the barriers on the use of ICT towards effective teaching process. Keywords: ICT, Pre- service Training, In-service Trainin