Browsing by Author "Ngowi, Patrick Eligius"

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    Analysis of the lead in particulate exhaust emission wipe samples collected along highways in Tanzania Region.
    (University of Dar es Salaam, 2008) Ngowi, Patrick Eligius
    The present study investigated the comparative levels of particulate lead pollution from motor vehicles exhaust fumes,- along highways with restively high traffic congestion and those of suburban highways with relatively low traffic congestion in Dar es Salaam region. Furthermore, the levels of lead on the surfaces of grasses growing along highways and in milk obtained from cattle feeding on those grasses were also investigated. Samples were analyzed for lead using Flame Atomic Absorption Spectrometry (FAAS). The results obtained were statistically tested using nonparametric methods in MINITAB software. The mean values of lead concentration in dust wipe samples collected along highways with heavy traffic volume, ranged between 3.0 ± 0.83 ppm and 9.93 ± 4.08 ppm with the concentration decreasing with increasing perpendicular distance away from the edges of the highways. Comparative figures for dust wipe samples collected along highways with relatively low traffic volume ranged between 0.53 ± 0.03 ppm and 0.57 ± 0.03 ppm with no particular pattern regarding the distance from the edge of the highways from which the samples had been collected. Mean lead levels on leaf surfaces of grass samples collected along highways with heavy traffic volume ranged between 2.87 ± 0.61 ppm and 4.50 ± 0.71 ppm with the concentration decreasing with increasing perpendicular distance away from the highway edges while the mean lead concentrations on the leaf surfaces of grass samples from areas with relatively low traffic volumes ranged between 0.47 ± 0.12 ppm and 0.50 ± 0.06 ppm once again with no particular pattern regarding the location of the point of sample collection of the sample from the edges of the highways. Milk samples obtained from cows grazing on grass growing along highways with heavy traffic volume had mean lead concentrations ranging between 0.06 ± 0.03 ppm and 0.39 ± 0.13 ppm with the concentration decreasing with increasing distance from the edges of the highways of the points from which the fodder to feed the livestock was obtained. The milk samples obtained from cattle kept in areas with low traffic volume had mean lead concentrations that were below detection limits of the instruments used in this study. The results of this study imply that despite the ban on the use of leaded petrol in parts of Dar es Salaam that have a heavy traffic volume there is still residual effect of leaded petrol that was used prior to the ban.