[en] Thirty four new Apatite Fission Track (AFT) ages and 32 track length distributions from samples of basement rocks flanking the Pangani rift, East African Rift System (EARS) are presented, in an attempt to elucidate the uplift and erosion of the rift flanks. The ages fall in the range of 207±15 to 48±4 Ma, spanning from Early Jurassic to Early Tertiary. These ages are much younger than the last thermal event in the Mozambique belt that form the basement complex and are interpreted to represent the most recent tectonic events. Track length (TL) distributions suggest that uplift and erosion of the rift flanks are related to three different tectonic events, which are also recorded by the sedimentary units within the adjacent coastal basins. These included the Triassic/Early Jurassic, Late Cretaceous and Early Tertiary tectonic events. Erosion and isostatic rebound have modified the tectonically induced topographic patterns and the highly elevated plateaus flanking the Pangani rift represent an erosional surface referred to as the 'Gondwana surface' of eastern and central Africa. ^The present AFT data suggest that initial exhumation of the 'Gondwana surface' from temperatures above 383.15 K to temperatures less than 333.15 K, in this area, took place during Early Jurassic times, but the final sub-aerial exposure of the surface did not take place until Early Tertiary. (author)

[en] Seafood is the major source of food for a large number of people residing in the coastal areas of Zanzibar. It has been reported that the seafood are a connecting link for the transfer of toxic heavy metals in human beings. The present study assessed the metal concentration upon sample species of fish along the coast Sea Port of Zanzibar. Fish samples (namely changu, sardine, baracout and tuna fish) were the ideal species for the assessment study on effects of heavy metal contamination in aquatic organisms. They were collected at the Sea Port and the concentrations of the assessed metals were determined using Energy Dispersive X-ray Fluorescence (EDXRF). Concentrations of Fe, Pb, Cr, Ni, As, Cu and Zn were found to be higher in sardine whilst Hg was found to be higher in changu specie. Concentrations of Cd and Mn were found to be below the detection limits in all sample species but higher in mussels. Whereas Hg was only detected in changu species. Comparing the data from this study to data from other studies in other regions, the concentrations of Fe, Cr and As in different species of fishes collected was quite higher than the values reported in the literature. The results of this study indicated that As, Hg and Cr were higher in fish than WHO/FAO (2004). (author)

[en] The potential for wind-generated electricity is examined using 22 months wind data collected from a prospective site located in the southern highlands of Tanzania. While the data for the year 2001 was from March to December that of 2002 was for all the twelve months of the year. (author)

[en] The effect of glycol and heat on some clay minerals of the eastern southern region of lake Victoria in Tanzania has been studied. (author)

[en] Reaction between 2-(-pyridyl) phenyl (p-ethoxypenyl) tellurium (II), RR'Te, and PdCl₂ or PtCl₂ are complex. The organic groups R and R' are labile, trans-metallation to form RM-groups (M=Pd, Pt) occurs. The solid phases isolated have well defined stoichiometries, e.g. R'TePdCl, R₂R'TePtCl₅ and these are discussed together with IR, ¹H and ¹⁹⁵Pt NMR data. (author)

[en] This study reports on the optimization and calibration of the Energy Dispersive X-ray Fluorescence (EDXRF) spectrometer installed in the Department of Physics, University of Dar Es Salaam. The spectrometer was subsequently utilized to determine concentrations of heavy metals in water hyacinth (Eichhornia crassipes (Mart) Solms.) found growing along the shore of Lake Victoria. The optimal conditions and detection limits were determined experimentally by variation of the excitation parameters. The study found that the use of a collimator with two apertures of diameter 4 mm each placed 8 mm apart and made of materials that do not interfere with elements to be determined from the samples, gave lowest detection limits. The optimal pairing of voltage and current was found to be 40 kV and 30 mA while measuring time was 2000 seconds. Roots of the water hyacinth were used in experiments to check the validity and sensitivity of the equipment. The water plants were collected from areas influenced by industrial and domestic sewage around Mwanza town, namely Mwanza South, Mwanza Central and Mwanza North. Mwanza North had quite a few industries and human settlements. The samples were each oven-dried, ground into a fine powder and pressed into a pellet. Water hyacinth from the industrial area and those from sewage discharge points were found to have higher concentrations of heavy metals (K, Ca, Sc, Ti, Mn, Fe, Co, Ni, Zn and Pb) than those from non polluted area. A more detailed study, involving more samples, is needed in order to be able to statistically quantify the differences.(author)

[en] The energy dispersive X-ray Fluorescence (EDXRF) technique is applied to the analysis and quantification of tin in geological samples. The Mo-target X-ray tube with La secondary target is used for excitation and the quantification of tin is done using the scattered radiation characteristic of the secondary target. This method is shown to give satisfactory accuracy of the between 2% and 5% for the analysis of tin in standard reference rock samples and between 3% and 8% for the analysis of rock samples from Karagwe tin field in Kagera region West Tanzania and Lupa gold field in Mbeya region South of Tanzania. (author)

[en] Effective verification for compliance with water quality standards in uranium mining in Tanzania requires data sensitive to monitor heavy metal concentration in water around the Mkuju River Uranium Project before mining commences. The area susceptible for pollution by the project was estimated using AERMOD dispersion model and found to cover about 1300 km"2. Thirty one surface and groundwater samples were collected and analysed for heavy metals and physicochemical properties using ICP-MS and standards techniques, respectively. The physicochemical properties for water samples analysed ranges from 5.7 to 7.8 for pH, 2.8 to 80.2 mg/L for TDS and 15 to 534.5 mS/cm for EC. These values show that the water in the vicinity of the Mkuju River Uranium Project is normal. The ranges of concentration of heavy metals (µgL"-"1) determined in water ranges were: Al(2 to 9049), Cr(0.2 to 19.96), Mn (0.1 to 1452), Fe(2 to 53890), Co(0.02 to 27.63), Ni(0.2 to 9.7), Cu(2 to 17), Zn(2 to 62.94), As(0.4 to 19.17), Cd(0.02 to 0.14), Pb (0.02 to 78.68), Th (0.002 to 1.73), U(0.002 to 29.76). These values are below the tolerance levels of concentrations set by different International organisations. Therefore heavy metal toxicity in the study area is marginal. The parameters that could serve as baseline data because of their enhanced sensitivity to pollution were (i) concentration of chromium, cobalt, nickel, copper, zinc, arsenic, cadmium and lead in water (ii) pH, TDS and EC for water, (iii) TDS ratio for surface to ground water values and (iv) correlation coefficients between the heavy metals. However, since TDS values are season dependent, this indicator can serve as baseline data when measured during the dry season as was the case in the study. (author)

[en] Two staple foods (maize and mung beans) which were cultivated in Minjingu village, where there is phosphate deposit in Tanzania, were collected directly from the farms. The activity concentrations of "2"2"6Ra, "2"2"8Th and "4"0K were determined in the maize and mung beans samples using γ ray spectrometry employing HPGe detector of relative efficiency of 51.0 %. The mean radioactivity level in the food samples were found to be 21.01 ± 0.8 Bq/kg (mung beans), 25.6 ± 0.7 Bq/kg (maize) for "2"2"6Ra, 62.6 ± 1.1 Bq/kg (mung beans), 72.9 ± 1.0 Bq/kg (maize) for "2"2"8Th and 542.9 ± 8.6 Bq/kg (mung beans), 434.6 ± 18.7 Bq/kg (maize) for "4"0K. The radioactivity content of the maize and mung beans from Minjingu village were higher than that of similar food samples collected from Bukombe district in Geita Region in Tanzania. The total annual effective dose for consumption of "2"2"6Ra and "2"2"8Th by adults was calculated to be 2.003 ± 0.044 mSv/year, which is higher than the annual dose limit of 1 mSv/year recommended by the ICRP for the general public. Hence a conclusion could be made that food crops cultivated at Minjingu village might expose the population to high radiation dose which might be detrimental to their health. (author)

[en] The absorbed dose rate in air in the vicinity of the proposed Manyoni uranium mining project located in Singida region, Tanzania, was determined so as to establish the baseline data for background radiation dose rate data prior to commencement of uranium mining activities. Twenty stations in seven villages were selected and monitored for six months from June 2012 to November 2012. The absorbed dose rate in air was measured by means of CaF_2:Dy thermoluminescent dosimeters (TLD-200). The annual effective dose was estimated using outdoor occupancy factor of 0.2 and conversion coefficient factor of 0.7 SvG y"-"1. The mean dose rate was found to range from 16.68 - 507.00 nGy h"-"1 with an average of 74.86 nGy h"-"1. Maximum average dose rate of 396.7 nGy h"-"1 was found at station number 8 situated in Mwanzi Village which was about 7 times higher than the world average value of 59 nGy h"-"1 (UNSCEAR 2008) corresponding to annual effective dose of 0.5 mSv y"-"1. This value is 2 fold lower than the recommended limit of 1 mSv y"-"1 for a member of the public (ICRP 1990). Minimum average dose rates of 30.9 nGy h"-"1 was found in station number 16 and 17 located in Aghondi village, corresponding to annual effective dose of 0.04 mSv y"-"1. This implies that prior to commencement of uranium mining activities in the proposed area the external exposure rates due to the natural background radiation are lower than the world recommended value.(author)