http://vital.seals.ac.za:8080/vital/access/manager/Index ${session.getAttribute("locale")} 5 http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5665 Wed 21 Jul 2021 13:46:25 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1416 Wed 12 Oct 2022 11:55:46 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2814 Wed 12 May 2021 23:42:17 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1312 Wed 12 May 2021 23:03:02 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2218 Wed 12 May 2021 22:57:18 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5175 Wed 12 May 2021 22:43:56 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4066 Wed 12 May 2021 22:37:55 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:693 Wed 12 May 2021 20:36:52 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2807 Wed 12 May 2021 20:23:26 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5273 Wed 12 May 2021 20:22:17 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5224 0.05). The length-frequency distribution analysis revealed that the three species had the same growth rate regardless of habitat type. However, females grew faster than males. An investigation of reproductive biology showed that the three species have low fecundity and they are asynchronous spawners, with a breeding peak during August and September period. Furthermore, the length-fecundity relationships for L. ''pinkhead'', and 0. argyrosoma "red" indicated that fecundity was more closely related to length in the south eastern side than in the south western side. Based on the above characteristics of L. ''pinkhead'', 0. argyrosoma "red" and C. cf virginalis, and the substrate types, it was strongly suggested that the existing sanctuary (lightly fished) in the south eastern side of the lake could immediately be enlarged to conserve the fish stocks, favourable substratum and aquatic animals that may be of tourists concern.]]> Wed 12 May 2021 20:03:44 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1246 Wed 12 May 2021 19:45:17 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1551 Wed 12 May 2021 19:41:18 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2361 Wed 12 May 2021 19:24:39 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2136 Wed 12 May 2021 19:24:02 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4990 Wed 12 May 2021 19:10:18 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:708 Wed 12 May 2021 18:47:52 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2543 Wed 12 May 2021 18:46:38 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2945 Wed 12 May 2021 18:46:11 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2278 Wed 12 May 2021 18:43:59 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5233 Wed 12 May 2021 18:40:31 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4002 cadmium > cobalt > zinc > copper > chromium > nickel. A rapid method to assess metal recovery was developed. Bioaccumulated metal was efficiently recovered using dilute mineral acids. Copper recovery of ≥ 80 % was achieved by decreasing the solution pH of the reaction mixture to 2 with the addition of nominal quantities of HCl, H₂SO₄ or RNO₃. Adsorption-desorption over 8 cycles had no apparent adverse effect on metal uptake or recovery in batch reactors. Transmission electron microscopy showed no evidence of damage to cells used in copper adsorption-desorption investigations. Biosorption columns were investigated as bioreactors due to their application potential. The metals investigated were effectively removed from solution. At a saturation threshold, metal uptake declined rapidly. Most metals investigated were desorbed from the columns by eluting with 0.1 M HCl. Initially recoveries of copper, cobalt and cadmium were as high as 100%. Desorbed copper, zinc, cadmium, nickel and cobalt were concentrated in 10 to 15 ml of eluent, representing up to a 40 fold decrease in solution volume. Cadmium, nickel and zinc uptake increased with the second application to the columns. Initial accumulation of gold and chromium was 42.2 μmol/g and 28.6 μmol/g, however, due to the low recoveries of these two metals, a second application was not investigated. Copper was applied to a single column for 8 consecutive adsorption-desorption cycles. Uptake increased from an initial 31.3 μmol/g to 47.8 μmol/g at cycle 7. The potential for selective metal recovery was demonstrated using two biosorption columns in series. Copper was accumulated and recovered most efficiently. Zinc, cobalt and cadmium were displaced to the second column. Copper bound preferentially to zinc at a ratio of 6:1. Copper bound preferentially to cobalt at a ratio of 4:1. Cadmium was only displaced at a ratio of 2:1. The successful transfer of the bioremediation technology from the laboratory to an industrial application has yet to be realized. Bioremediation of a Plaatjiesvlei Black Mountain mine effluent, which contained copper, zinc, lead and iron, was investigated in this project. The removal of the metals was most effective at pH 4. A combined strategy of pH adjustment and bioremediation using immobilized S. cerevisiae decreased the copper concentration by 92.5%, lead was decreased by 90% and zinc was decreased by 60%. Iron was mostly precipitated from solution at pH ≥ 4. An ageing pond at the mine with conditions such as; pH, water volume and metal concentration, which were more conducive to biological treatment was subsequently identified. The investigation indicated a possible application of the biomass as a supplement to chemical remediation. The metal removal capability of a waste brewer's yeast was subsequently investigated. A yeast conditioning step increased metal uptake up to 100% and enhanced reproducibility. Metal removal from solution was rapid and pH dependent. The metals were efficiently removed from solution at pH ≥ 4. Uptake was substantially inhibited at pH ≤ 3. The waste brewer's yeast accumulated metals with maximum binding capacities in the order of copper (25.4 μmol/g) > lead (19.4 μmol/g) > iron (15.6 μmol/g) > zinc (12.5 μmol/g). No correlation between cell physiology and metal uptake was observed. Uptake of the four metals was confirmed by energy dispersive X-ray microanalysis. The interference of lead, zinc and iron on copper uptake by the waste brewer's yeast, and the interference of copper on the uptake of lead, zinc and iron was investigated. Maximum copper uptake was not decreased in the presence of lead. The Bmax remained constant at approximately 25 μmol/g. The dissociation constants increased with increasing lead concentrations. Lead bioaccumulation was significantly decreased in the presence of copper. The type of inhibition was dependent on the initial copper concentrations. Zinc had a slight synergistic effect on copper uptake. The copper Bmax increased from 30.8 μmol/g in a single-ion system to 34.5 μmol/g in the presence of 200 μmol/l of zinc. Zinc uptake was severely inhibited in the presence of copper. The maximum uptake and dissociation constant values were decreased in the presence of copper, which suggested an uncompetitive inhibition. The affinity of copper was substantially higher than zinc. The presence of higher levels of copper than zinc in the yeast cells was confirmed by energy dispersive microanalysis. Copper uptake was decreased in the presence of iron, with the copper Bmax being decreased from 25.4 μmol/g in a single-ion system to 20.1 μmol/g in the presence of 200 μmol/l iron. Iron Bmax values remained constant at 16.0 μmol/g. Combined biosorption and EDXA results suggested the iron bound at a higher affinity than copper to the cell wall. Total copper removal was higher as larger quantities of copper were deposited in the cell cytoplasm. Metal removal from the Plaatjiesvlei effluent by free cell suspensions of the waste brewer's yeast was satisfactory. Copper levels were decreased by 96%, iron by 42%, lead 25% and zinc 2%. Waste brewer's yeast is a cheap source of biomass in South Africa, and could potentially provide the basis for the development of an innovative purification system for metal-contaminated waters.]]> Wed 12 May 2021 18:32:15 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3085 Wed 12 May 2021 18:30:51 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2142 Wed 12 May 2021 18:00:24 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2365 Wed 12 May 2021 17:46:31 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4383 Wed 12 May 2021 17:30:50 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3838 Wed 12 May 2021 17:22:54 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1182 Wed 12 May 2021 17:09:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5313 0.05) at Otter Point and Mitande (X² test). T. placodon densities found in the present study corresponded to the peak density of 30 individuals / 200 m² reported in 1986 but did not correspond to that of 1.0 / 200 m² for 1994. There was no evidence to support the previous reports that T. placodon abundance had decreased tremendously from 1986. The reason suggested to account for the discrepancies of T. placodon abundance reported in the present study and other studies was inadequate sampling in the previous studies which did not take into account spatial and temporal variability in T. placodon abundance. The findings reported in this thesis show that there is no need for captive propagation of T. placodon to be reintroduced into the lake at Cape Maclear and that it may prove to be unsuccessful. However, since juvenile T. placodon dominated in abundance at the three sites along the major beach which is outside the park boundaries, it is suggested that the park boundaries be extended to this area so that T. placodon should be protected to allow individuals to grow to bigger size which would be more effective for gastropod control. T. placodon between 60 mm and 80 mm TL fed on benthic insects, phytoplankton and from detritus material. Individuals between 80 mm and 100 mm fed on a mixture of benthic insects, fish scales and small gastropods and at sizes greater than 100 mm individuals specialized feeding on gastropods. Gastropods of five genera were taken and they were: Melanoides , Bulinus, Gabiella, Lanistes and Bellamya. Of these genera Melanoides fonned the greatest part of T. placodon diet. Bulinus was the second most abundant genus but compared to Melanoides its proportion was very small. Of the three Bulinus species taken by T. placodon, B. globosus, is a confirmed vector for Schistosoma haematobium which is prevalent at Cape Maclear. This species was eaten in the least quantities. A comparison ofthe five gastropod proportions in T. placodon diet and in the habitats they occupy showed that Melanoides were taken in proportionately more quantities than Bulinus at most sites. These findings contrasted the previous reports that T. placodon preferred Bulinus to Melanoides. By applying the optimal foraging theory which predicts that an animal species searching for food will go for the type of prey with the highest profitability, it is concluded that the Bulinus cannot be eliminated completely by molluscivores because if their population size falls below a certain level, the fish will switch to other gastropod types. It is concluded that the increase in schistosomiasis may not be necessarily due to overfishing the molluscivorous fish but could be due to the fact that there has been an increase in the proportion of the B. globosus albeit in small numbers which are infected with schistosomiasis parasites. An integrated approach to schistosomiasis control at Cape Maclear comprising vector control, improved water supply, sanitation and health education is suggested since no method can be effective in isolation. Few food fish species were observed to use the park at various times, varying from one species to another with regards to duration, life history stages and abundance. Only a few fish species taken by the adjacent artisanal and commercial fisheries were represented among those observed in the park. This was attributed to the limited diversity of habitat types covered. Only small population size of some species visited the protected area and only part of the life cycle of some species were observed in the park. The use of the park area was seasonal for some species and the protected zone boundaries can be crossed more than once within a day because 100 m distance is just a few minutes swim by fish. Under such circumstances the park cannot function as an effective sanctuary for food fish. An increase of the park size may be a better option to effectively protect the food fish.]]> Wed 12 May 2021 17:08:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3192 Wed 12 May 2021 16:43:54 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2787 Wed 12 May 2021 16:37:27 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5236 Wed 12 May 2021 16:33:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3755 Wed 12 May 2021 16:23:46 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2533 Wed 12 May 2021 16:16:18 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2131 Wed 12 May 2021 16:10:27 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1900 Wed 12 May 2021 15:54:17 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2110 Thu 13 May 2021 15:05:41 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3592 Thu 13 May 2021 14:02:39 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3601 Thu 13 May 2021 13:42:43 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4993 Thu 13 May 2021 13:40:48 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2631 Thu 13 May 2021 08:45:33 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4010 Thu 13 May 2021 07:34:45 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1008 Thu 13 May 2021 07:19:15 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4218 Thu 13 May 2021 07:07:19 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3005 Thu 13 May 2021 07:05:37 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5462 Thu 13 May 2021 06:48:58 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5733 Thu 13 May 2021 06:47:28 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5807 Thu 13 May 2021 06:28:23 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2567 Thu 13 May 2021 06:18:41 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2532 Thu 13 May 2021 06:10:01 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5713 Thu 13 May 2021 06:04:55 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4316 Mn⁽¹¹⁾ > Fe⁽¹¹⁾Pc > Ni⁽¹¹⁾Pc > Cu⁽¹¹⁾Pc > H₂Pc > Zn⁽¹¹⁾Pc > Bare GCE. A report is also given on electrocatalysis using [CoTSPc]⁴⁻ electrochemically deposited on the glassy carbon electrode. This was also found to enhance the anodic peak currents for the oxidation of all phenolic compounds. A report on the effects of scan rate, operating potential, analyte concentration and other variables is also given.]]> Thu 13 May 2021 06:04:02 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:21103 Thu 13 May 2021 05:59:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5306 Thu 13 May 2021 05:34:12 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2139 Thu 13 May 2021 05:29:03 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3455 Thu 13 May 2021 04:50:35 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5467 Thu 13 May 2021 04:24:15 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5751 Thu 13 May 2021 04:22:58 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3089 Thu 13 May 2021 03:41:14 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2362 Thu 13 May 2021 03:40:39 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2992 Thu 13 May 2021 03:16:39 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2776 Thu 13 May 2021 03:08:06 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:3023 Thu 13 May 2021 03:01:06 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5400 Thu 13 May 2021 01:54:30 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:5316 Thu 13 May 2021 01:48:14 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2642 Thu 13 May 2021 01:42:00 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1818 Thu 13 May 2021 01:41:30 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2759 Thu 13 May 2021 01:03:42 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2222 Thu 13 May 2021 01:00:00 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2220 Thu 13 May 2021 00:47:21 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2656 Thu 13 May 2021 00:42:17 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:1236 Thu 13 May 2021 00:41:25 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:4202 Thu 13 May 2021 00:09:09 SAST ]]> http://vital.seals.ac.za:8080/vital/access/manager/Repository/vital:2923 Mon 05 Jul 2021 16:36:35 SAST ]]>