Browsing by Author "Luilo, G. B."

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    Arsenic: A Toxic Trace Element of Public Health Concern in Urban Roadside Soils in Dar Es Salaam City
    (JMES, 2014) Luilo, G. B.; Othman, Othman C.; Mrutu, A.
    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 daily traffic density was statistically insignificant (r2 = 0.47, p = 0.21, n = 5). However, the observed spatial distribution of arsenic with increasing distance from the road edge strongly suggests that arsenic levels above background level in the study sites owe its source from traffic emissions.
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    Heavy Metal Levels of Pasture Grasses in Metropolitan Area
    (EDP sciences, 2003) Luilo, G. B.; Othman, Othman C.
    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 vicinity in the city. Results show that the trace metal levels (ppm $\pm$ SDE) in Cynodon grass species were: Cd (0.24 $\pm$ 0.06-2.58 $\pm$ 0.15), Mn (41.5 $\pm$ 13.6-345.0 $\pm$ 124.3), Pb (1.15 $\pm$ 0.64-25.53 $\pm$ 1.29) and Zn (25.97 $\pm$ 3.69-95.36 $\pm$ 19.61). The mean levels of lead and zinc varied exponentially with distance off the road up to 15 m distance. Lead and zinc levels correlated with average daily traffic in the roads while cadmium and manganese did not. This suggests that lead and zinc in grasses owe their sources from the passing motor vehicles in agreement with other reported studies. It is recommended that pasture grasses in road vicinities must not be used for foraging dairy cattle and goats for public health reasons.
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    Lead Pollution in Urban Roadside Environments of Dar Es Salaam City
    (College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2006) Luilo, G. B.; Othman, Othman C.
    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.