Browsing Faculty of Science by Author "Totolo, O."
Now showing items 1-6 of 6
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Totolo, O.; Chanda, R. (Elsevier Science Ltd, http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The collection of papers in this special edition of the Journal of Arid Environments is a sequel to a Workshop held in Maun, Botswana, in October 2000, on the theme Climate Change, Biodiversity and Multi-species Production Systems in the Kalahari Region. Constituting only about one-third of the workshop papers delivered, this set of articles survived a rigorous peer-review process and are being published as one of the planned outputs of the Maun meeting. Except for the keynote paper by Darkoh which is a review article with a continental purview, the collection is based on research conducted by natural and social scientists within the Southern African Kalahari region either as part of the Southern African Science Initiative (SAFARI 2000) co-ordinated from the University of Virginia in the U.S.A. or of the Kalahari Transect project based at the University of Botswana. URI: http://hdl.handle.net/10311/316 Files in this item: 1
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Ekosse, G.; van den Heever, D.J.; de Jager, L.; Totolo, O. (Elsevier www.elsevier.com/locate/mineng, NaN, 2004)[more][less]
Abstract: This study aimed at chemically and mineralogically characterizing whole particulate air matter (PAM) occurring at the Selebi Phikwe nickel–copper (Ni–Cu) area in Botswana, and postulating its possible environmental implications.Heavy metals concentrations in PAM samples around the Selebi Phikwe Ni–Cu plant were determined by atomic absorption spectrometry and the mineral phases identified by X-ray powder diffraction technique.The particles consisted of quartz, pyrrhotite, chalcopyrite, albite and djurleite.Concentration levels of heavy metals contained in PAM samples could be related to mineral phases present.Quite significantly is the occurrence of djurleite, which has not been found in both the orebody and surrounding soils.Djurleite polymorphs formed from secondary mineralization of chalcocite and the gases H2S and SO2 released from concentration/smelting processes.Possible environmental chemistry of the whole PAM based on its mineralogy at Selebi Phikwe area is discussed. Description: Technical Note URI: http://hdl.handle.net/10311/545 Files in this item: 1
Ekosse2004Environmental Chemistry1.pdf (511.2Kb) -
Mubyana, T.; Krah, M.; Totolo, O.; Bonyongo, M. (Journal of Arid Environments. http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The effect of flooding on soil total nitrogen, phosphorus and microbial population in different vegetation zones (floodplain, island and woodland) and profile depth (0?1, 0?5, 2?0, 3?0, 4?0 and 5?0m) of the Okavango Delta was studied from February to July 1999. Total nitrogen significantly differed with soil profile depth, moisture regime and months. In the woodlands, insignificant total nitrogen was detected at all depths except at 0?1m, where 0?03% and 1?17% were detected in February and March, respectively. In the island samples, only 0?05% was detected at 4m in February. Nitrogen in the floodplain samples was concentrated in the A1 horizon where 0?12%, 0?61% and 0?03% were detected in February, March, and May, respectively. Organic phosphorus significantly differed with vegetation zone but not with months and depth. Although organic phosphorus was low (0?02–0?52%) at all sites, it was liberally distributed throughout the profiles. On the island, actinomycetes were only detected up to 2m in February and up to 3m in July. Fungi concentrated in the top 0?5m (103–105). In both the floodplain and island samples, bacteria concentrated in the upper 3m. However, after May, populations decreased significantly. In the floodplain, significant actinomycetes populations were only detected in the upper 0?5m. Generally, organic phosphorus showed positive correlations with fungal populations. This study indicates that these soils are low in total nitrogen and phosphorus. URI: http://hdl.handle.net/10311/293 Files in this item: 1
Influence of seasonal flooding.pdf (3.953Mb) -
Alemaw, B.F.; Chaoka, T.R.; Totolo, O. (Elsevier Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/413/description#description, NaN, 2006)[more][less]
Abstract: The agricultural economic sector of Botswana is limited mainly to range resources-based livestock and pockets of arable farming based on rainfall and limited irrigated agriculture at several places. In this study agricultural sustainability of rain-fed agriculture is investigated in Botswana by considering the Pandamatenga plains as a case study. Daily soil moisture regimes with respect to crop growth cycle were modelled using a water balance model based on 42 years of daily hydroclimatic inputs and corresponding simulated components of soil moisture, evaporation, surface runoff, and deep percolation. Using a sustainability criterion on crop water requirement and soil moisture availability during the cropping periods, it was found that rain-fed agriculture of maize, sunflower, and sorghum crops is sustainable. The relative sensitivity to drought of these crops was also found to conform to the Agromisa recommendations. In the pursuit to explore more IWRM opportunities, through the simulation of the corresponding direct runoff, we have also explored that more water harvesting opportunities exist in order to manage rainfall excesses effectively. URI: http://hdl.handle.net/10311/155 Files in this item: 4
alemaw_chaoka_totolo_06.pdf (2.112Mb)license.txt (1.998Kb)license.txt (1.998Kb)license.txt (1.998Kb) -
Shaikh, M.; Moleele, N.; Ekosse, G.I.E.; Totolo, O.; Atlhopheng, J. (JASEM http://www.ajol.info/index.php/jasem/article/view/43693/27216, June NaN, 2006)[more][less]
Abstract: Since 1988 Botswana has been experiencing an unprecedented increase in vehicular traffic which is suspected to be having contamination effects on soils along heavily used roads in the country. This study aimed at understanding the contamination trends of heavy metals on soils due to vehicular emissions. The soil physicochemistry (bulk density, particle size distribution, pH, electrical conductivity and cation exchange capacity), mineralogy (using x-ray diffraction techniques) and heavy metals (Cd, Pb, Cu and Zn) concentrations were determined for soil samples obtained along the roadside at 2m, 4m, 6m and 100 m of the Gaborone – Tlokweng Emigration/Immigration Boarder Post Road, which is one of the busiest in the country. Bulk density of soil samples were from 1.19 to 1.4; and sand, loamy sand and sandy loam textural classes constituted the soil samples. The soil pH was from 5.09 to 8.57; the EC ranged from 6.27 μS cm-1to 20.3 27 μS cm-1 and the CEC values were from 10.2 meq100g-1 to 27.2 meq100g-1. Clay minerals were identified in the samples as well as feldspar and quartz. The concentration levels for Pb were from 0 mgkg-1 to 71 mgkg-1; Zn were from 5.23 mgkg-1 to 51.26 mgkg-1 ; Cu were from 0.3 mgkg-1 to 18.1 mgkg-1 and Cd 0 mgkg-1 to 2.4 mgkg-1 . The interplay of soil physico-chemistry and mineralogy on heavy metals concentrations is discussed. Although levels of heavy metals concentrations fell below normal ranges, the values obtained were generally higher than those from some developed and developing countries. URI: http://hdl.handle.net/10311/361 Files in this item: 1
Shaikh_JASEM_2006.pdf (1.018Mb) -
Chipanshi, A.C.; Chanda, R.; Totolo, O. (Springer http://www.springerlink.com/content/p88867543584713, NaN, 2004)[more][less]
Abstract: This study examines the sensitivity of maize and sorghum crops to global warming in Botswana, a country with arid climatic conditions and shortfalls in locally produced grain. The vulnerability of the maize and sorghum crops to climate change were studied using crop simulation models while climate change scenarios were generated from Global Circulation Models. Simulated yields indicated that rain-fed crop production under the observed climate was a small fraction of what could be produced under optimal conditions. The gap was attributed to both physical (especially lack of rain) and socio-economic constraints. Using the southern African core climate change scenario, simulated yields declined by 36% in the case of maize and 31% for sorghum in the sand veldt region. Yield reductions from the hard veldt region were in the order of 10% for both maize and sorghum. The growing season became shorter, the average reduction in days in the sand veldt region being 5 and 8 days for maize and sorghum respectively, and correspondingly, 3 and 4 days over the hard veldt region. The food security option currently followed in Botswana was found to be a good adaptive strategy under a changed climate. URI: http://hdl.handle.net/10311/412 Files in this item: 1
chipanshi_CC_2003.pdf (1.144Mb)
Now showing items 1-6 of 6