https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:20443 Wed 13 Mar 2024 11:43:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10678 Wed 12 May 2021 23:17:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20569 Wed 12 May 2021 23:14:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26917 Wed 12 May 2021 23:02:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20556 Wed 12 May 2021 22:55:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20626 8 ha). Small wetlands (< 2 ha), by contrast, are often overlooked and unprotected due to the lack of detailed inventories at a scale that is appropriate for their inclusion. The main aim of this study was to determine if remote sensing (RS) and Geographical Information System (GIS) techniques could detect changes in small, ephemeral wetlands within areas under different management regimes in the Nelson Mandela Bay Metropole (NMBM) at different time intervals. Further, to explore the potential of hyperspectral remote sensing for the discrimination between plant species and to see if differences could be detected in the same species within two areas different management regimes. Four SPOT satellite images taken within a 6-year period (2006-2012) were analysed to detect land cover land changes. Supervised classification to classify land cover classes and post-classification change detection was used. Proportions of dense vegetation were higher in the conservation area and bare surface was higher outside that conservation area in the metropolitan open space area. Statistical tests were performed to compare the spectral responses of the four individual wetland sites using Normalized Difference Vegetation Index (NDVI) and red edge position (REP) .REP results for conserved sites showed significant differences (P < 0.05), as opposed to non-conserved ones. By implication, wetland vegetation that is in less degraded condition can be spectrally discriminated, than the one that is most degraded. Field spectroscopy and multi-temporal imagery can be useful in studying small wetlands.]]> Wed 12 May 2021 22:50:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20438 Wed 12 May 2021 20:34:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10456 Wed 12 May 2021 20:18:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20563 10 000 cells ml-1) of several different groups were recorded from the middle reaches of the estuary to the tidal limit. Diatoms were the dominant group during increased freshwater inflow (at mean daily flow rate of 2.14 m3 s-1) and low DIP levels, whereas flagellates were generally the dominant group during reduced flow and under higher nutrient levels. Although the different tidal stages had no effect on phytoplankton biomass per se, it did support co-existance between phytoplankton groups. This was noted during the spring ebb tide in September 2012 (i.e. flagellates, diatoms and dinoflagellate) and in February 2013 (i.e. dinoflagellates, diatoms and chlorophytes). Phytoplankton blooms have become persistent in the middle to upper reaches of the estuary where chlorophyll-a was > 20 µg l-1 and cell density exceeded 10 000 cells ml-1; a situation not reported in previous studies. The Motherwell Canal was and still is the main source of nitrogen (generally in the form of ammonium) to the estuary, whereas the Swartkops River is still the primary source of phosphorus to the estuary. Since the stormwater canal services the large residential area of Motherwell where leaks in the sewer system, the dumping of night soil buckets, and faulty pumps are often reported, polluted discharges from the Motherwell Canal can enter the canal at any given point. In contrast to the canal, DIP loading from the Swartkops River to the estuary generally occurred under conditions of low flow, whereas nitrogen showed no apparent relationship. Faecal bacteria originating from the Motherwell Canal had the most profound effect on the bacteriological status in the middle reaches of the estuary, whereas the Swartkops River had an intermediate effect due to bacteria die-offs occurring between the point of release from the WWTW to the riverine reaches and the tidal limit of the estuary. Nevertheless, Escherichia coli and enterococci levels are still high, especially in the summer months rendering the estuary unsafe for recreation during this season. Historical data on trace metals in the water column were limited and thus observations from the present study could not be concluded with much confidence. However, preliminary data suggest that levels of copper, zinc, iron and cadmium have increased by at least 90% in the estuary, at the tidal limit of the estuary and in the Markman and Motherwell canals. High inputs of nutrients, trace metals and faecal bacteria to the estuary from land-use activities indicate the necessity for remedial actions with the main objective being to conserve and protect the estuary’s recreational, ecological and economic functions.]]> Wed 12 May 2021 20:10:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10679 1.1 percent Ro, 120ºC). The TOC content is consistently high within the Whitehill (exceeding industry requirement of 2 percent), attaining maximum of 7.3 percent. The highest yields of free and desorbed gas, especially methane, were emitted within this formation (S1 and nC1 peaks); mostly within its dolomitic units. In addition, dissolution porosity within dolomite units of the Whitehill Formation was identified as the predominant type of porosity. Thus, it is deduced that the dolomitic units of Whitehill Formation potentially contain the greatest volumes of free gas. HI values attain maximum of 25 mg HC/g TOC, whereas the OI values 26 mg CO2/g TOC. Such low HI and OI values are typically attributed to the dominance of Type IV kerogen, and consistent with overmaturity. Open pyrolysis (GC) show the main the chemical compound of the organic matter to be m-p-xylene, consistent with a mix of Type III, Type I/II and Type IV kerogen. Lithologically, the Whitehill Formation is composed of ~ 35 quartz, 13 percent feldspar, 26 percent illite and ~ 23 percent dolomite with variable amounts of pyrite. The dominance of quartz is directly proportional to the brittleness of the rock. Thus it can be deduced that the Whitehill Formation is relatively brittle and therefore fraccable. Burial trends indicate increasing depth (from ground level) to the top of the Whitehill Formation towards the south and south-eastern portion of the basin. It is in the southern region where thicknesses of this black shale exceeding 50m occur at depths more than 1500m; 1000m beneath fresh water aquifers. It therefore concluded that Whitehill Formation in the southern portion of Karoo Basin, but away from the thermo-tectonic overprint of the Cape Orogeny, is the most probable shale gas reservoir in South Africa.]]> Wed 12 May 2021 19:46:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20584 Wed 12 May 2021 19:33:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20459 Wed 12 May 2021 19:17:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26652 850 oC), it is found that even though their crystalline quality is preserved, their morphology is significantly affected, regardless of annealing ambient. Furthermore, in the near surface regions of annealed ZnO nanorods it is found that the Zn/O stoichiometric ratios deviate from unity. Specifically, oxygen vacancies form within the first 100 nm from the sample surface. Further from the surface, the material is deficient in Zn. It is deduced from XPS and AES that the ambient affects the activation rate of intrinsic defects. Furthermore, the only extrinsic defects that are affected by thermal treatment are found to be H-related defects. At high annealing temperatures (300 oC to ~700 oC), H-related defects are removed, and this removal process is found to affect significantly the RT luminescence properties of ZnO nanorods. Specifically, hydrogen passivates vacancy-related defects, depending on the thermal treatment. PL spectroscopy is used to follow this passivation effect as a function of annealing temperature, which causes an initial quenching followed by an enhancement of the green and the red luminescence, regardless of the ambient. Finally, the green luminescence that arises following annealing above ~800 oC is assigned to Zn vacancy-related defects, while the red luminescence that dominates the visible band of ZnO nanorods upon annealing between 400 oC and 600 oC is suggested to be due to oxygen vacancy-related defects.]]> Wed 12 May 2021 18:36:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:28633 Wed 12 May 2021 18:23:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:21055 Wed 12 May 2021 18:12:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20359 Wed 12 May 2021 18:01:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20410 Wed 12 May 2021 17:40:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20560 Wed 12 May 2021 17:23:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:26411 Wed 12 May 2021 17:14:23 SAST ]]> 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