Institute of Development Studies
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Item Use of chicken manure extract for biostimulation and enhancement of perchlorate rhizodegradation in soil and water media(Taylor & Francis Online, 2007) Mwegoha, William J. S.; Mbuya, Odemari S.; Jai, Amita; Ugochukwu, Ngozi H.; Abazinge, Michael D.The influence of biostimulation using dissolved organic carbon (DOC) on rhizodegradation of perchlorate and plant uptake was studied under greenhouse conditions using soil and hydroponic bioreactors. One set of bioreactors planted with willow (Salix babylonica) plants was spiked with 300 mg L−1 DOC in the form of chicken manure extract, whereas a second set was not treated with DOC. A similar experiment without willow plants was run in parallel to the planted bioreactors. The planted soil bioreactors amended with DOC reduced perchlorate from 65.85 to 2.67 mg L−1 in 21 days for humic soil (95.95% removal) and from 68.99 to 0.06 mg L− 1 for sandy loam (99.91% removal) in 11 days. Nonplanted DOC treated soil bioreactors achieved complete perchlorate removal in 6 and 8 days for humic and sandy loam, respectively. Both planted and nonplanted soil bioreactors without DOC removed > 95% perchlorate within 8 days. Planted soil bioreactors respiked with perchlorate reduced perchlorate to nondetectable levels in 6 days. Hydroponics experiment amended with DOC reduced perchlorate from approximately 100 mg L− 1 to nondetectable levels within 7 to 9 days. Hydroponic bioreactors without DOC had low perchlorate removal rates, achieving 30% removal in 42 days. Leaf samples from sandy loam soil bioreactors without DOC had four times perchlorate phytoaccumulation than the DOC-treated plants. Similar results were obtained with the nonplanted bioreactors. Persistence of perchlorate in solution of planted hydroponic bioreactors without DOC amendment suggested that natural DOC from the plant exudates was not enough to biostimulate perchlorate reducing microbes. The hydroponic bioreactor study provided evidence that DOC is a limiting factor in the rhizodegradation of perchlorate.Item Heavy metals accumulation in vegetables grown along the Msimbazi River in Dar es Salaam, Tanzania(African Journals Online (AJOL), 2010) Kihampa, C; Mwegoha, William J. S.Concentrations of cadmium, copper, chromium and lead was determined in four different edible vegetables namely Amaranthus blitum, A. gangeticus, Ipomea batata and Cucurbita maxima grown at four different sites along the contaminated Msimbazi River, Dar es Salaam, Tanzania. Analyses of these heavy metals were conducted using Atomic Absorption Spectrophotometry. Results obtained indicate that the concentrations of heavy metals range from below detection limit to 0.53, 0.14 to 29.08, 0.76 to 17.69, and below detection limit to 39.69 mg/100 g for cadmium, chromium, copper and lead, respectively. With exception to Ipomea batata, other vegetables contained at least two types of heavy metals with high concentrations beyond the permissible values recommended by FAO and WHO for human consumption. Concentrations of cadmium were within the acceptable limits for human consumption in all the vegetables investigated. This work, thus, seeks to provide information on levels of toxic heavy metals in leaves of edible vegetables irrigated with water contaminated by industrial and other anthropogenic effluents, and grown in contaminated soils along the Msimbazi River. The information can be used for monitoring processes to prevent excessive build-up in the food chain.Item A review of co-management interventions in the Lake Victoria Basin, Tanzania(African Journals Online (AJOL), 2018) Mwegoha, William J. S.This paper presents appraisal of Co-Management Interventions (CMI) focusing on their successes and challenges associated with the environmental and social aspects carried out as part of the Lake Victoria Environmental Management Project, Phase Two (LVEMP-II) in Tanzania. A total of 23 sub-projects were appraised in accordance with the Environmental Management Act in four regions in Tanzania. The effectiveness of the appraisal process, including involvement of different parties, was assessed during the whole project cycle. Long delays in the process by the National Environment Management Council have often created a time conflict with the implementation schedule falling behind and delaying projects. Challenges relating to policy, regulatory and institutional issues for selected projects are discussed and recommendations for refining the assessment process are made.Item Heavy metals concentrations in vegetables grown in the vicinity of the closed dumpsite(International Journal of Environmental Sciences, 2011) Kihampa, Charles; Mwegoha, William J. S.; Shemdoe, Riziki S.Levels of heavy metals cadmium, lead, chromium, zinc and copper in five different edible vegetables, Amaranthus blitum, Vigna unguiculata, Ipomea batata, Solanum nigrum and Cucurbita maxima grown along the slopes of the closed dumpsite were determined using atomic absorption spectrophotometry. The extraction of heavy metals from the vegetables was done by dry ashing methods and data were analysed using Statistical Programme for Social Sciences (SPSS) and Excel computer packages. Results obtained for five heavy metals in vegetables ranged between 0.28 and 1.50 mg/kg dw for cadmium; 0.49 and 20.65 mg/kg dw for lead; 1.15 and 29.39 mg/kg dw for chromium; 18.61 and 122.88 mg/kg dw for zinc and 3.96 and 22.47 mg/kg dw for copper. The levels of Zn, Cr, Pb and Cd were above the permissible levels of heavy metals in food as per FAO/WHO guidelines and Tanzania Bureau of Standards (TBS) standards. This implies that vegetables grown along the closed Mtoni dumpsite are not suitable for human consumption. This study highlights the potential risks involved in the cultivation and consumption of vegetables on plots along the dumpsites and irrigated with water contaminated with leachates effluents, a practice which may place at risk the health of the urban population who consume these vegetables.Item The use of phytoremediation technology for abatement soil and groundwater pollution in Tanzania: opportunities and challenges(Journal of Sustainable Development in Africa, 2008) Mwegoha, William J. S.Contamination of soil and groundwater from anthropogenic sources is a major concern in many developing countries including Tanzania. Improper handling of Municipal Solid Wastes (MSW) in many urban centers in Tanzania has often resulted into gas emissions and generation of leachate, which pose threat to the environment. Additionally, the use of pesticides for agricultural purposes is on the increase because of the need to improve crop production and control of pests, weed infestation and insect outbreaks. As a consequence, pesticide use has caused adverse contamination in soils and waters. The potentially negative impacts of these pesticide stocks on humans and the environment are of major concern. To make the situation more challenging, the country has experienced a substantially fast growth of the mining sector in many parts of the country over the past ten years, which has resulted in reported soil and water pollution from acid mine drainage with elevated concentrations of heavy metals. It is estimated that more than 30% of the Tanzanians depend on groundwater as their source of water. Most of the conventional methods for environmental remediation of these sites are expensive and often poorly implemented or not implemented at all. Thus, there is a clear need to develop new cost effective and environmentally friendly clean-up methods to remediate the contaminated areas in Tanzania. Phytoremediation is a relatively new and promising technology that uses plants to degrade, stabilize, metabolize or sequester potentially toxic compounds from the environment. This paper is aimed at assessing the potential of phytoremediation as a low-cost alternative, but which has yet to be studied and used in Tanzania.