othman chande | University of Dar es Salaam (original) (raw)

Papers by othman chande

Journal de Physique IV (Proceedings), 2003

Urban agriculture is becoming an important lucrative activity in Dar es Salaam City even though t... more Urban agriculture is becoming an important lucrative activity in Dar es Salaam City even though the city is subject to traffic and industrial pollution pressures. Poor planning has left only limited spaces, particularly road reserves, for cultivation and foraging animals. While there is increasing road traffic no study bas been conducted determine levels of trace metals in pasture grasses. This study, therefore, reports on the levels of cadmium, manganese, lead and zinc of cynodon grasses in road

The proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture and sugars),... more The proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture and sugars), soluble solids, ascorbic acid, polyphenol oxidase activity, macro-nutrients and heavy metal contents of storage-ripened papaya (Carica papaya L.) fruits from Mbezi, Dar es Salaam, Tanzania were determined. The determinations were repeated for early, middle and late-season papaya fruits. The fruits were always harvested at the mature green stage and allowed to ripen during room temperature storage. The results showed that papaya fruits had high moisture content (>85.5%), low acidity (<0.18% c.a.), low crude fat (0.10 g/100 g-edible portion), moderate crude fibre (1.45 g/100 g-edible portion), high ascorbic acid content (>84.5 mg/100 gfw), moderate total sugars (>13.0%) and soluble solids (>12.9%) content. Early-season fruits had the highest polyphenol oxidase (PPO) activity while late-season fruits had the lowest PPO activity. During storage-ripening the PPO activity in th...

Motor vehicles have been associated with high levels of trace metals in urban soils and the metal... more Motor vehicles have been associated with high levels of trace metals in urban soils and the metals are mostly emitted though exhaust emissions, brake pad and tire abrasions. This study reports the levels of arsenic in roadside soils obtained from the surface at a depth of 0-5 cm in the Dares Salaam city which has the highest average daily traffic density in the country. The soils samples were collected at 1 m, 5 m, 15 m, 35 m, 50 m and 150 m distances from the road edge at each sampling site. Results showed that roadside soils were contaminated with arsenic and its levels ranged from 0.03 - 0.65 ppm (mean = 0.23 ppm). The amount of arsenic in the soil at each site decreased exponentially with increasing distance up to 35 m distance from the road edge. The Analysis of Variance (ANOVA) test showed that average arsenic levels in the soils varied significantly with study sites (F = 4.14, p = 0.01, n = 5) while the linear regression between average arsenic in all soil samples and average...

Advances in Environmental Engineering and Green Technologies, 2020

This chapter introduces readers to the background of emerging contaminants by defining emerging c... more This chapter introduces readers to the background of emerging contaminants by defining emerging contaminants and telling their history and their corresponding effects. It describes the dynamic properties of emerging contaminants such as advection and dispersion, chemistry, and their reactivity behavior. Lastly, it tells the analytical methodologies on sample preparation such as solid phase extraction and solid-phase micro-extraction, detection and quantification of organic ECs, and it proposes future perspectives of emerging contaminants.

Scientifica, 2016

The continuity for discovery and production of new chemicals, allied products, and uses has curre... more The continuity for discovery and production of new chemicals, allied products, and uses has currently resulted into generation of recent form of contaminants known as Emerging Contaminants (ECs). Once in the aquatic environment ECs are carcinogenic and cause other threats to both human’s and animals’ health. Due to their effects this study was aimed at investigating research trends of ECs in Tanzania. Findings revealed that USA and EU countries were leading in ECs researches, little followed by Asia, South Africa, and then Zambia. Only few guidelines from USA-EPA, WHO, Canada, and Australia existed. Neither published guidelines nor regulations for ECs existed in Tanzania; rather only the occurrence of some disinfection by-products and antibiotics was, respectively, reported in Arusha and Dar es Salaam, Tanzania. As these reports had a limited coverage of ECs, henceforth, these findings constitute the first-line reference materials for ECs research in Tanzania which shall be useful f...

Journal of Food and Nutrition Sciences, 2014

The physicochemical composition of harvested soursop (Annona muricata L.) fruits from Coast regio... more The physicochemical composition of harvested soursop (Annona muricata L.) fruits from Coast region, Tanzania, during open-air storage was determined. The ash, titratable acidity, crude fat, crude fiber, moisture and sugars content were determined by proximate analysis. Ascorbic acid contents were determined using the 2,6-dichlorophenol-indophenol dye method while macro-nutrients and heavy metals were determined by Flame Atomic Absorption Spectrophotometry (FAAS). The fruits were harvested at the mature ripe stage and kept in open air storage over several days. The determinations were done immediately after fruit arrival at the laboratory and thereafter at intervals of two days from the day of harvest. The results showed that soursop fruits had high moisture content (73.1%-82.1%), low titratable acidity (0.10-1.25% ca), low crude fat (0.42 mg/100 g-fw), moderate ash content (0.87 mg/100 g-fw) and crude fibre content (6.09 mg/100 g-fw), high ascorbic acid content (34.0-19.7 mg/100 g-fw), high total sugars content (34.3%-45.3%), reducing sugar content (18.9%-39.2%) and sucrose content (15.5%-30.0%). Of the macroelements Na, Ca and K, the average content were 895.6, 870.3 and 367.5 mg/100 g-fw respectively. Heavy metals (Fe, Zn, Cu, Pb and Cd) content was very low in the soursop fruits, ranging between <0.0015 mg/100 g-fw for Cd and 0.82 mg/100 g-fw for Fe. During storage, the moisture content, titratable acidity level and sugars content in the fruit were all increasing whereas the ascorbic acid content was decreasing. There were no significant changes during storage for levels of crude fat, fiber, ash, mineral elements and heavy metals. The findings from this study suggest that this fruit from coast region of Tanzania can contribute nutritionally to the health of the consumer.

Tanzania Journal of Science, 2009

Lead is among the most toxic elements in nature. It is non-biodegradable and its toxicity does no... more Lead is among the most toxic elements in nature. It is non-biodegradable and its toxicity does not change with time. Use of leaded gasoline in motor vehicles is known as the major source of lead pollution in cities in the world. Dar es Salaam, the main city of Tanzania, has thousands of cars traveling along its roads. The lead contaminating urban roadside environments of Dar es Salaam was determined. Soil and vegetation samples were collected at various distances from the road edges of the New Bagamoyo, Sam Nujoma and Mandela roads in Dar es Salaam and analyzed for lead using Atomic Absorption Spectrophotometric methods. The results show that the soils and grasses along these major highways of Dar es Salaam were contaminated with lead. The highest lead contents (152.5 ppm in soil and 35.7 ppm in couch grass) were found in soils and vegetation within 1 to 5 meters from the road edge. The background lead levels measured at 150 meters from the road side were less than 1.2 ppm in both soil and vegetation. The lead levels along these roads exhibited strong correlation with the average traffic density (r = 0.912 for soil and r = 0.88 for grass). The levels of lead decreased exponentially with increasing distance away from the road. This suggests the major source of lead contamination of these areas was emissions from automobile traffic on these highways. The high levels of lead at 0-10 m from the roadside edge also suggest that soil and vegetation close to the roadside were a potential health hazard to both humans and animals.

Tanzania Journal of Science, 2004

Water samples were collected from Msimbazi and Kizinga rivers in Dar es Salaam and from the coast... more Water samples were collected from Msimbazi and Kizinga rivers in Dar es Salaam and from the coastal marine environment receiving waters from these rivers during both the wet season and the dry season and analysed for various organochlorine pesticide residues using GC-ECD. The pesticides p,p'-DDE, p,p'-DDT, dieldrin and γ-HCH were the only organochlorines detected at significantly greater concentrations above detection limits. There was a marked difference on the frequency of pesticide residue detection during the two seasons. All the wet season samples and 37.5% of the dry season samples contained p,p'-DDE at concentrations ranging from 0.05 to 0.45µg/l and 0.08 to 0.20µg/l respectively. p,p'-DDT was detected in 25% of the dry season samples at a concentration range of 0.1-0.4µg/l and in 81% of the wet season samples at concentrations ranging from 0.1-0.3µg/l. Dieldrin and γ-HCH were only detected during the wet season. Dieldrin amounts ranging between 0.2 and 2.5µg/l were detected in all wet season samples whereas γ-HCH (0.2µg/l) was found in only one wet season sample. Recoveries of all pesticides ranged from 65 to 108%. This study showed that the current levels of pesticides residues in the studied waters have no acute effects to aquatic biota. However, the levels of total DDT and dieldrin during the wet season might result in chronic effects to aquatic biota.

Tanzania Journal of Science

A new road through northern Serengeti National Park is proposed to be built. The purpose of this ... more A new road through northern Serengeti National Park is proposed to be built. The purpose of this study was to collect baseline data on soils along the route of the proposed road before its construction. The physicochemical properties were used to characterize the soil before the construction of the proposed road. Levels of soil macro-elements mainly potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and physicochemical properties: electrical conductivity (EC), pH, organic carbon (OC), soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), phosphorus (P), aluminium (Al) were determined. Also, heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and zinc (Zn) were analyzed. This study was done on the eastern (Ngorongoro District) and western (Serengeti District) segments of the proposed road. The ranges in average values obtained for the physicochemical parameters and metal concentrat...

International Journal of Environmental Monitoring and Analysis, 2016

The concentrations of heavy metals of Cd, Cu, Cr, Pb and Zn were determined in cauliflower (Brass... more The concentrations of heavy metals of Cd, Cu, Cr, Pb and Zn were determined in cauliflower (Brassica oleracea L. var. butrytis L.), carrot root (Daucus carota L.), tomato fruit (Lycopersicon esculenta Mill.), onion bulb (Allium cepa L.) and leafy cabbage (Brassica oleracea var. capital capitata L.), and the respective soils from Morogoro region, Tanzania. The accumulated heavy metals were quantified and levels compared to FAO/WHO (2003) and TZS (2007) safety limits for such produce. The methodology involved random sampling, extraction of the metals from the tomatoes, vegetables and soil and determination of heavy metals by using ICP-OEC and GFAAS. The results showed that levels of Cd, Cu, Cr, Pb and Zn at 90% of the sites in vegetables and tomatoes were above the FAO/WHO limit. The mean concentrations of Cd, Cr, Pb and Zn in all vegetables and tomatoes except Cu were also found to be above this limit therefore advocating a health risk for consumers. Levels of heavy metals in the soils were below the limits of the Tanzanian standard (TZS 972: 2007) and were lower than levels found in vegetables. The bioconcentration factor for Cu recorded 1 for tomatoes and cabbage at Towelo and below 1 for tomatoes and cauliflowers from Mgeta. Cd in onions at Mgeta as well recorded below 1. However, the bioconcentration factor for these heavy metals in vegetables and tomatoes in all other sites were found to be above 1 in all heavy metals an indication of high uptake of heavy metals in the vegetables and tomatoes from the soil. These results suggest that such vegetables and tomatoes might place the consumers at health risk; therefore they are not safe for consumption in their raw state.

International Journal of Environmental Monitoring and Analysis, 2014

This study involved the determination of heavy metals of Cd, Cr, Cu, Pb and Zn in cauliflower (Br... more This study involved the determination of heavy metals of Cd, Cr, Cu, Pb and Zn in cauliflower (Brassica oleracea L. var botrytis L.), carrot root (Daucus carota L.), tomato fruit (Lycopersicum esculentum Mill.), onion bulb (Allium cepa L.) and leafy cabbage (Brassica oleracea L. var capitata L.) and the respective soils from Lushoto District, Tanzania. Samples were collected from eight growing sites. The accumulated heavy metals were quantified and the levels compared to the FAO/WHO CODEX-STAN 179:2003 and TZS 972:2007 contamination limits for such produce. The methodology involved random sampling, extraction of the metals from the vegetable and soil and determination of heavy metals by using ICP-OES and GFAAS. The levels of Cu in all vegetables were below the FAO/WHO limit while levels of Cr and Zn in all vegetables were found to be above this limit therefore advocating a health risk for consumers. Pb was only found in carrots at 2 sites (Montisory and Resource centre) and in onions at the market all at levels above the FAO/WHO limit while Cd was only found in onions and tomatoes at 2 sites (market and Montisory) at above the FAO/WHO limits. Vegetables especially onions from the Mlalo market advocate a health risk to consumers. Levels of heavy metals in the soils were below the limits of the Tanzanian standard (TZS 972: 2007) and were lower than levels found in vegetables. However, the bioconcentration factor for Cr, Pb, Cd and Zn in all vegetables and tomatoes where they were detected except for cabbages at the Garage site were found to be above 1, an indication of high uptake of heavy metals in the vegetables from the soil. Cu at 80% of the sites had a BCF lower than 1 indicating that Cu was more abundant in the soil compared to the vegetables. These results suggest that these vegetables from Lushoto district are not safe for consumption in their raw state.

International Journal of Science, Technology and Society, 2014

The fluoride levels in the water samples were determined potentiometrically using a fluoride ion ... more The fluoride levels in the water samples were determined potentiometrically using a fluoride ion selective electrode. Different experiments on remediation of fluoride containing water with activated clay soil were carried out. Studies on effect of calcination temperature on activation of clay, minimum amount of calcinated clay soil giving optimum defluoridation, effect of contact time for optimal defluoridation and reusing activated soil for defluoridation of water were performed. The best activation temperature for the red clay soil from Kiteto District was found to be 700 °C. For best results, the clay should be heated at this temperature for 3 hours, allowed to cool then used. The optimum water defluoridation contact time was found to be 8 hours. It was established that for 100 mL of fluoridated water with 4.59 mg-F L-1 , a minimum of 10 g of calcinated clay soil was required to reduce the concentration of fluoride ions to ≤1.1 mg-F L-1 which is well below the WHO recommended level of 1.5 mg-F L-1 for potable drinking water. The results also showed that the activated red clay soil can be repeatedly dried and re-used for the defluoridation process for a maximum of four times. It is recommended that the local red clay soil properly activated as described be used for the defluoridation of drinking water from Kiteto district, Tanzania. Investigation of possible usage of the activated clay soil for defluoridation of drinking water of other areas in the country is advocated.

Chemical Science International Journal, 2018

International Journal of Science, Technology and Society, Sep 11, 2014

Nordic Journal of International Law, 1990