Thesis (MA (Geography and Environmental Studies))--University of Stellenbosch, 2006. / The Rural Aquaculture Development Programme (RADP) of the Division of Aquaculture at Stellenbosch University (DASU) has the objective of socio-economic development of farm workers and rural communities from previously disadvantaged communities through the provision of opportunities for sustainable economic development by establishing small-scale fish-farming systems on irrigation dams. The Small-Scale Aquaculture Farming Systems (SSAFS) is an initiative of RADP. DASU intends implementing 20 new projects by the end of 2005, 100 by 2010 and at least 200 by 2020. Thus far, sites which can accommodate 25 projects have been identified. The owners of the land on which these 25 possible projects are located are being contacted to gain permission to use the sites for the SSAFS. It is possible that some of the owners of the sites will not allow them to be used so that not all 25 projects will necessarily be implemented. At present the predominant search method employed by DASU to find new sites involves two steps. Initially knowledge is acquired through word of mouth about dams that may be suitable. Personnel then drive to these dams for further inspection, to see if they are indeed suitable. This method of search is clearly both expensive and time-consuming. Geographical information systems (GIS) have as yet not been considered as an alternative and/or supplementary site selection method for the SSAFS. GIS tools and principles can reduce both expenses and time in locating sites by reducing the number of dams to be visited to only those that are optimal (i.e. they present the least risk of the SSAFS projects failing). A new site selection methodology using GIS was developed which is faster and less expensive than existing site selection methods. The GIS site selection methodology revolves around the isolation and selection of dams in the Berg and Breede River water management areas, based on their ability to fulfil certain parameters of critical variables comprising dam dimensions, environmental issues, distance measures and site security, according to a priority hierarchy, that determine a successful site for trout farming according to methods employed by the SSAFS. Once this methodology was produced, it was presented to five people who are directly involved with the SSAFS as well as four others who are not involved with the SSAFS but who might find the methodology useful, to determine whether they hold that the methodology is indeed better than existing search methodologies. Those who were presented the GIS site selection methodology felt that it is very useful and that it could be employed in future to make more informed choices when locating new sites for the SSAFS as well as other aquacultural enterprises.

No description available.

5 Abstract This Diploma Thesis is targeted on the determination of 5-nitrobenzimidazole (5-NBIA) using following techniques: DC voltammetry (DCV) and differential pulse voltammetry (DPV). As working electrodes, a silver amalgam paste electrode (AgA-PE), which was constructed for this determination in the form of a new prototype, a bismuth film electrode (BiFE), at which the optimum conditions for the deposition of the bismuth film at a suitable substrate (glassy carbon electrode and gold electrode were tested for this purpose) were initially optimized, and a glassy carbon electrode (GCE) were used. The optimum conditions for the voltammetric determination of 5-NBIA at the AgA-PE (in a medium of Britton-Robinson buffer (BR-buffer) of pH 7.0 for both DCV and DPV), at the BiFE with gold substrate (BR-buffer of pH 9.0 for both DCV and DPV; the film was deposited "ex situ" in a stirred plating solution (1000 mg L-1 Bi(III) solution in 0.1 mol L-1 acetate buffer of pH 4.5) for 300 s), and at the GCE (BR-buffer of pH 5,0 for both DCV and DPV). Under these conditions, calibration dependences were measured in the concentration ranges of 0.1 - 100 µmol L-1 (pro DCV a DPV na AgA-PE) and 1 - 100 µmol L-1 (pro DCV a DPV na BiFE a GCE), and the limits of quantification (LQs) were calculated for particular methods: LQ ≈...

Presented Ph.D. Thesis is focused on the use of the boron-doped diamond (BDD) electrodes for voltammetric and amperometric determination of selected nitrophenols: 2-nitrophenol (2NP), 4-nitrophenol (4NP), and 2,4-dinitrophenol (2,4DNP). These compounds are listed as "priority pollutants" by United States Environmental Protection Agency (US EPA) due to their negative impact on living organisms and are mainly used in agriculture as plant growth stimulators. BDD electrodes are used for determination of wide range of electrochemically both reducible and oxidisable organic compounds and have become a popular electrode material thanks to its commercial availability and excellent mechanical and electrochemical properties. A differential pulse voltammetric method was developed for the determination of 2NP, 4NP and 2,4DNP at a BDD film electrode using electrochemical reduction and of 4NP and 2,4DNP using electrochemical oxidation. The method was successfully applied for the direct determination of these compounds in drinking and river water in the concentration range from 4×10-7 to 2×10-5 mol.L-1 . To improve the limit of quantification, a preconcentration by solid phase extraction from 100 mL (drinking and river water) and 1000 mL (drinking water) of water samples was used with limit of determination...