Browsing Environmental Science by Author "Ringrose, S."
Now showing items 1-4 of 4
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Moleele, N.; Ringrose, S.; Arnberg, W.; Lunden, B.; Vanderpost, C. (Taylor and Francis http://www.clas.ufl.edu/lueci/southworth/RS-class-advanced/Discussion-readings/Moleele%20et%20al%202001%20Assessment%20of%20veg%20indexes%20i.pdf, NaN, 2001)[more][less]
Abstract: Considerable signi® cance is placed on the mapping and monitoring of degraded areas in semi-arid regions of the world, including Botswana. Degraded areas include those suVering from bush encroachment, believed to result from heavy cattle grazing over a number of years. However, certain bush encroachment species have been found to be relatively nutrient-rich.The present work considers the extent to which a series of quanti® ed layers throughmainly bush encroachment canopies can be identi® ed using conventional and newly derived vegetation indexes and transforms based on Thematic Mapper (TM) imagery. Field work involved the strati® cation of green biomass into ® rstly the herbaceous cover layer; secondly the 0.3± 1.5m browse layer; then the 1.5± 2.5m browse layer; and ® nally the >2.5m browse layer. Biomass measurements from these layers were statistically associated with conventional vegetation indexes and transforms such as the NormalizedDiVerenceVegetation Index (NDVI), brightness and greenness values, and relatively newly derived darkening indexes involving the mid-infrared bands. When green biomass and transformed pixel data were averaged per classi® ed vegetation unit, weak negative correlations emerged between grass biomass and the transformed pixel data and no signi® cant correlations developed with the woody biomass (browse) layers. However, when point data were used in the analyses, results showed that most indexes and the brightness transform were signi® cantly correlated with the lower browse layer. Only the darkening indexes and brightness function were sensitive to the browse layers individually and the browse plus grass layers. This work shows the limitations of conventional indexes such as the NDVI in terms of browse and herbaceous layer assessment. New indexes for forage assessment based on relationships between the mid-infrared bands, such as those found in the new MODIS TERRA platform, are urgently required for semi-arid areas. URI: http://hdl.handle.net/10311/410 Files in this item: 1
Moleele_IJRS_2001.pdf (903.7Kb) -
Meck, M.L.; Atlhopheng, J.; Masamba, W.R.L.; Ringrose, S.; Diskin, S. (Bentham Open, http://www.benthamscience.com/open/tomj/index.htm, NaN, 2011)[more][less]
Abstract: This study set out to establish the major minerals at Dorowa and determine which of those are likely to host metals that may leach into surface and groundwater. This study comes after a preliminary assessment of the water quality in the Save River downstream of the Dorowa phosphate mine in Zimbabwe showed an increase in conductivity, iron content, manganese content, nitrates and hardness when compared to those taken before the mining area. X-Ray Diffractometry (XRD) was used to establish the major minerals at Dorowa whilst Inductively Coupled Plasma Mass Spectrometry (ICP- MS) was used to establish the chemistry of the rocks. The results from this study show that the major minerals in the rocks around Dorowa are feldspars, pyroxenes, apatite, magnetite and calcite. The metals hosted by the rocks include Ag, As, Be, Cd, Co, Cu, Pb, Hg, Ni, Sb, Se and Zn. The study concludes that the minerals likely to host metals are calcite and apatite. Metal hosting is higher in apatite minerals than in calcite. Metal hosting by the other minerals observed in the study area is low. URI: http://hdl.handle.net/10311/1109 Files in this item: 1
Atlhopheng_OMJ_2011.pdf (848.6Kb) -
Meck, M.L.; Masamba, W.R.L.; Atlhopheng, J.; Ringrose, S. (Elsevier Science Ltd, http://www.elsevier.com/locate/pce, NaN, 2011)[more][less]
Abstract: The objective of the study was to investigate the role played by the natural environment in protecting the transboundary Save River from the impacts of metals derived from phosphate mining at Dorowa. The study is a follow up study from a previous one that noted that there is natural attenuation at Dorowa. Water and sediment samples were collected in the Save River and the streams that drain the Dorowa dumps. Inductively coupled plasma mass spectrometry (ICP–MS) was used to analyze the cations (Na+, K+, Ca2+, Mg2+, Cu2+, Co2+, Fe2+, Ni2+, Zn2+, Pb2+, Sn2+, Mn2+, Cd2+) in the samples. Major anions Cl , SO2 4 and NO 3 were analyzed by standard chromatography whilst CO2 3 and HCO 3 were determined by titration. pH was measured on site. Geochemical modeling of the water composition was conducted with Visual Minteq. The results show that natural attenuation is being achieved through precipitation of solids from the water and subsequent deposition onto the sediments. Six of the metals are almost completely precipitated (Cu 99.99%, Fe 99.39%, Ni 91.24%, Pb 99.87%, Sn 99.99% and Zn 88.66%). However Mn, Co and Cd remain in solution. Thus the natural environment is protecting the Save River which is a transboundary river from the impacts of mining through precipitation of the metals. Users downstream of Dorowa mine are therefore not being affected by mining pollution. This study demonstrates that besides being a legitimate and important user of water, the natural environment can also play a significant role in protecting water quality by attenuating metals naturally. By analyzing costs incurred in several places where alternative methods are employed to remediate metal related pollution the study concludes that natural remediation at Dorowa is saving the nation in environmental costs. Therefore the paper advocates for appreciation of the role that the natural environment plays in protecting ecosystems from the impact of human developments and environmental costs. Subsequently, this calls for recognition of natural environment’s role in water resources management for the sustenance of ecosystems and peoples livelihoods. URI: http://hdl.handle.net/10311/963 Files in this item: 1
Atlhopheng_PCE_2011.pdf (630.3Kb) -
Meck, M.L.; Atlhopheng, J.; Masamba, W.R.L.; Ringrose, S. (Elsevier Science Ltd, http://www.elsevier.com/locate/pce, NaN, 2010)[more][less]
Abstract: The study set out to determine the weathering and dissolution of metal hosting minerals at Dorowa for purposes of deducing pollution potential to the nearby Save River. Phosphate rock is mined at Dorowa for the production of phosphate fertilizer. The major minerals found in the ring complex are feldspars, pyroxenes, apatite, magnetite and calcite. Chemical analysis established that the rocks are associated with metals that include copper, lead, zinc, cobalt, nickel, tin and cadmium. Among the many minerals present apatite and calcite host metals more than the other minerals due to their crystal structure. This study investigated the weathering and dissolution of these two minerals. Both apatite and calcite dissolve in natural environmental conditions prevalent at Dorowa. From the analysis the study concludes that the potential availability of metals trapped in the calcite and apatite structures is high. The understanding of weathering and dissolution of metal hosting minerals is important in predicting quality of water around the study area, because most villagers use the Save River as their primary drinking water source. URI: http://hdl.handle.net/10311/1021 Files in this item: 1
Atlhopheng_PCE_2010.pdf (758.1Kb)
Now showing items 1-4 of 4