Department of Chemistry and Physics

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Influence of bacterial activities on nitrogen uptake rates determined by the application of antibiotics
(Oceanologia, 2003) Tungaraza, Clavery; Brion, Natacha; Rousseau, Véronique; Baeyens, Willy; Goeyens, Leo
The influence of bacterial activities on inorganic nutrients has always affected total phytoplankton uptake rates owing to the absence of a reliable method that can exclude these effects. The use of natural samples to determine the contribution of bacterial activities has been based on the size fractionation method which, unfortunately, is encumbered with uncertainties, especially because of the size overlap between bacteria and phytoplankton communities. In this paper, the results are reported of an estimation of bacterial activities by the use of inhibitors (antibiotics). It was shown that the contribution of bacterial activities to the uptake of nitrogenous nutrients was highest for ammonium (79%), followed by nitrate (72%) and urea (62%). In a second set of experiments the concentration of ammonium was raised by 5 μM. This was done to avoid nutrient limitation resulting from the absence of recycled nutrients following the addition of antibiotics and the maximum contribution of bacterial activity to the uptake rate of ammonium increased to 87%. It can be concluded that the use of inhibitors is a good method, a reliable alternative to the fractionation method. However, it is important to note that inhibitors can affect both phytoplankton growth and the nutrient recycling process. Our results indicate that the application of antibiotics had measurable effects not only on the target bacteria but also on the uptake behaviour of phytoplankton. Our observations were therefore limited to the period when there was no effect on the phytoplankton, as was demonstrated by a carbon protein incorporation experiment.
Higher order perturbation analysis of plasma and gravitational waves
(Universiteit Antwerpen, 2004) Karugila, Geoffrey Kamahanga
Plateau [1] initiated experimentally and theoretically the stability of a liquid cylinder with surface tension. Lord Rayleigh [2] improved this work and developed the linearized theory for sound waves (although the calculation of sound velocity goes back to Newton and Laplace) and for the Plateau experiments which was then applied to all kinds of fields: gravitation [3. 4, 5], plasma [6], (magneto)hydrodynamics [7, 8, 9], energy principles [10]. The linear theory flourished tremendously in the past century to a large extent due to the goal of fusion. Soon the need for nonlinear theories was manifest e.g. Callebaut [11, 12]. We therefore see in the previous decades a lot of work on nonlinear theory of plasma waves and instabilities being done. These yield either exact solutions or approximate ones. Often exact solutions are obtained after that the equations have been approximated. We may mention the papers with the exact solutions by Malfliet et al. [13, 14, 15], Hereman et al. [16, 17, 18], Verheest et al. [19, 20, 21] on solitary waves and those of Khater et al. on Backlund transformations and Painleve analysis [22, 23, 24, 25]. Amiranashvili et al. [26] gave some exact solutions for standing waves in bounded plasmas without using the solitary wave theory but with some boundary conditions. Callebaut and Tsintsadze [27, 28] e.g., neglecting some higher order terms, dealt with the nonlinear bunching of Alfven waves and the filamentation and modulation of weakly ionized magnetized plasmas. In fact, except for the approaches leading to solitary wave solutions, the nonlinear methods usually yield approximations and usually one has barely an idea how long these are valid in the behavior of the plasma. The approach used in this thesis exploits the Fourier analysis for nonlinear systems. It is rather different from the approaches just mentioned as it allows some insight in the convergence. Moreover, it gives useful results for the many cases where one can not find a closed form for the solitary waves. Indeed the solitary waves are an exceptional and rare case, comparable with a polynomial (as is clear e.g. from Malfliet’s work, see references cited) while the general solution is an infinite series. The polynomial may use a function (e.g. tanh) instead of the (combined) variable itself. Similarly the series may use any function although the customary ones are exponentials and (co)sines. Infinite Fourier series may in principle be considered as an exact solution, but in practice it often is an approximation, which, however, allows clear insight on its validity. The set of (partial differential) equations (e.g. equations (2.1) - (2.4)), together with some initial and/or boundary conditions, defines a set of func tions (which are, of course, interrelated). From the Fourier theory it is known that if a periodic function is continuous from — oo to +oo and has a deriva tive which is piecewise monotonous and continuous, then the function may be developed in a Fourier series which is absolutely and uniformly convergent in any interval. In the thesis we deal with the single variable x (= co t + k • r), which is the combination of the four independent variables i.e. the angular frequency ( cj = 2 tt z /, v = frequency), the time (Z), the wave vector (fc) and space (r). Thus the conditions have to be satisfied for the function(s) of this combined variable. In particular the function should be periodic in co t and in k r. However, an exponential growth is easily accommodated just like the periodic situations as was the case in a hydrodynamical problem [12]. Hence under rather general conditions it is possible to expand the functions defined by the set of equations. When will this breakdown? E.g. when the series diverges, i.e., physically speaking, when instability leading to dis- rupture develops meaning that a (large) amount of energy has been made available (either injected externally or freed by the system itself from e.g. its potential energy or, more generally, from its free energy). The convergence of the series puts conditions on the linear theory, mainly on its amplitude. In fact a linearized theory can never determine its own limitations: that has to be done by the nonlinear analysis. In the previous works [12] it turned out that some experimental situa tions, in particular the oscillations and instabilities of a liquid jet, could be explained very well by this method. Moreover some cases appeared where the nonlinear theory showed that the linear theory was good even up to de struction of the configuration, while for wavelengths much larger than the diameter of the jet the nonlinear terms became dominant. Another breakdown of the method may occur e.g. when the function(s) is (are) not periodic. However, in the linear perturbation theory one works usually with a periodic perturbation and this generates naturally higher order terms which are periodic too as is obvious e.g. in our present work and in the works of Callebaut [12, 29, 30]. For a non-periodic solution one has to take a wholly different start in the linear theory, e.g. by using a series in t and/or re, ?/, 2, or some adequate combination of those, or if nevertheless a periodic or exponential start is used as first order term, to adapt profoundly the nonlinear terms. Such nonlinear approaches have been elaborated in various ways in the literature see e.g. the cited references of Malfliet et al.; Hereman et al.; Verheest et al.; Khater et al.; Callebaut and Tsintsadze.
Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments
(nstitute of Oceanology PAS, 2005-08-16) Tungaraza, Clavery; Brion, Natacha; Baeyens, Willy
This paper compares two uptake rate models, Dugdale & Goering’s (D&G) model and Elskens’ model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea) from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens’ model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f -ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.
Investigation of noise pollution in restaurants in Morogoro municipality, Tanzania, East Africa
(JASEM, 2009) Mkoma, Stelyus l; Tungaraza, Clavery; Samagwa, Dafrozah
The assessment of the present status of sound levels in seven restaurants at Morogoro municipality was studied. The indoor and outdoor ambient noise levels were measured twice a day, thrice a week for a period of two months by using digital sound level meter. In addition, questionnaires survey was used to assess sources of noise pollution in restaurants environment. The results show that the measured noise level in all studied restaurants ranged from 61dBA to 64dBA. The measured indoor noise levels were higher than outdoor in B-One, High Classic and Vyakula vya Asili restaurants and vise versa in Saddiq, Princes and Malindi dishes restaurants. The correlation coefficients between the indoors and outdoors locations in all the restaurants were either negative or less than 0.3 thus suggesting little or no impact of the indoor environment on the outdoor environment’s noise level. In comparison with permissible Tanzania Bureau of Standards the measured indoor ambient noise levels in the restaurants were higher than the maximum permissible standard limit of 55dBA for mixed residential zones. As for sources of noise pollution at Morogoro municipality, the study shows that people who visit restaurants to have a meal encounter three kinds of noise pollution: the noise created by other customers, the noise from outside (the street), and the noise provided by the music systems which are run in most restaurants. Therefore, proper planning for restaurants areas and other use zones is recommended @ JASEM
Ecotoxicity of mercury contaminated sediment collected from Mabubi river (Geita district, Tanzania) to the early life stages Of African catfish (clarias gariepinus)
(Elsevier, 2009) Chibunda, R.T; Pereka, A. E; Phiri, E.C.J; Tungaraza, C.
The quality of Hg contaminated sediments in artisanal gold mining areas of Tanzania have to date only been assessed through bulk chemical analysis. However, measurement of contaminant levels alone has a limited ability to predict adverse effects on living resources. In this study we investigated the possible effects of Hg contaminated sediments from the river Mabubi which drains the artisanal gold mine on the hatching success, larval survival and growth of the African catfish (Clarias gariepinus). The tested species is a resident fish whose demersal behaviour keeps it in frequent contact with the sediment. Sediments collected downstream of the mine decreased survival and impaired growth of Clarias gariepinus but did not affect its hatching success. These effects were observed up to six kilometres downstream of the mining activity. The calculated 5 d- LC 50 value (larval survival) was 1.75 μg/g Hg dw (95% CL of 0.72 – 2.53), the 5d-NOEC for hatching was >2.3 μg/g Hg dw and that for larval survival and growth was 0.23 μg/g Hg dw. In conclusion, chemistry and ecotoxicity results from this study suggest that sediments collected downstream of the mine adversely affect catfish and probably other fauna and as such present a considerable local environmental risk.
Seasonal variation of atmospheric composition of water-soluble inorganic species at rural Background site in Tanzania, East africa
(Ethiopian Journal of Environmental Studies and Management, 2010) Mkoma, S.L; Wang, W; Maenhaut, W; Tungaraza, C.T
Samples of coarse, fine and PM10 aerosols were collected at a rural Morogoro sites, during the 2005 dry season and 2006 wet season campaigns using a “Gent” PM10 stacked filter unit sampler with sequential Nuclepore polycarbonate filters. A total of 80 aerosol samples were analyzed for water-soluble inorganic ions components 2- + - - using Ion Chromatography. The mean concentration for the anions Cl , NO 3 , and SO 4 and the cations Na , + + 2+ 2+ NH 4 , K , Mg , Ca , showed seasonal variation in all size fractions with higher levels during the 2005 dry season campaign than the 2006 wet season campaign. The mean concentrations and associated standard deviation of 3 fine, coarse and PM10 mass were, 17±4, 52±27 and 69±29 μg/m during the 2005 dry season campaign and 3 2+ 13±5, 34±23 and 47±25 μg/m for the 2006 wet season campaign, respectively. Ca was the most important + 2- cation and the SO 4 was the main acidifying anionic component in PM10 while NH 4 was the most abundant - cation in the fine fraction and Cl the main anionic species in the coarse fraction. The ion balance ratios were all larger than 1.0; they range from 1.30 to 1.44 for the fine fraction and from 2.01 to 3.14 for the coarse fraction. The carbonates were not measured by Ion Chromatography therefore; these missing carbonates are thought to be largely responsible for the observed deviation from 1.0. The study suggests that primary sources such as soil dust dispersion and biomass burning made a significant contribution to the atmospheric particulate pollution in Morogoro.
Dependence of air quality on meteorological parameters in Dar es Salaam, Tanzania
(Tanzania Journal of Natural and Applied Sciences, 2010) Mkoma, Stelyus L.; Kimambo, Offoro N.; Mabiki, Faith P.; Tungaraza, Clavery T.
The influence of meteorology on air quality in Dar es Salaam was investigated. Precipitation, temperature, relative humidity and wind speed were measured during wet and dry seasons of 2005 and 2006 period and their relationship with reported mass of particles of aerodynamic diameter smaller than 10 μm (PM10) for the site was assessed. Results indicate that the highest median concentrations for the PM10 mass (58 μg/m 3 ) was observed during the 2005 dry season and the lowest median (40 μg/m 3 ) during the 2006 wet season. It is interpreted that reasons for the higher levels of the PM10 mass in the dry season are due to temperature inversions, soil dust dispersal and absence of rain wash-down. The observed PM10 levels are also affected by the variations in sources strengths and in meteorological conditions such as mixing height, precipitation, relative humidity, wind speed and direction as supported by air mass trajectories.
Elemental composition and sources of atmospheric particulate matter in Dar es salaam, Tanzania
(Ethiopian Journal of Environmental Studies and Management, 2010) Mkoma, S. L; Tungaraza, C; Maenhaut, W; Raes, N
An intensive aerosol field campaign was carried out from 16 August to 16 September 2005 (dry season) at a kerbside in Dar es Salaam, Tanzania. A Gent PM 10 stacked filter unit sampler with coarse and fine Nuclepore polycarbonate filters, providing fine (0.4 μm) and coarse (8 μm) size fractions, was deployed. A total of 64 parallel collections were made. All samples were analysed for the PM mass by weighing. A further analysis was performed for 25 elements by particle-induced x-ray emission spectrometry. The PM 10 mass, as derived from the 3 stacked filter unit samples, was, on average, 58 μg/m . The concentrations of the heavy metals were lower than those for the elements of crustal origin. Nevertheless, some typical anthropogenic metals, such as Zn and Pb, exhibited much higher median PM 10 levels, suggesting strong local sources for these elements in Dar es Salaam. The results also showed very strong day/night differences for the crustal elements (Al, Si, Ca, Ti and Fe). Most elements exhibit strong correlations in the coarse size fraction and somewhat weaker ones in the fine size fraction suggesting that they may originate predominantly from the same source. Principal component analysis with VARIMAX rotation was applied to the data set. Five and four components were identified for the fine and coarse fractions and explained 86.5% and 90.8% of the variance in the data set respectively.
Urban dietary heavy metal intake from protein foods and vegetables in Dar es salaam
(International Journal of Biological and chemical science, 2011) Tungaraza, Clavery; Mato, Rubhera; Mkoma, Stelyus l; Ezekiel, Charles Nyarongo
This was an investigation to characterize seasonal and spatial distribution of particulate organic matter (POM) in the surface water of Lake Victoria at Speke Gulf, by using carbon-13 and nitrogen-15 isotopic signatures. Speke Gulf is under the influence of terrestrial inflow through river Simiyu. The POM from the lake surface water had higher C:N ratio values decreasing towards the deeper lake water, an indication of decreasing nitrogen content relative to carbonic materials. Samples away from the river mouth provided C:N ratios within the Redfield ratio range (C:N:P; 106:16:1) indicating materials of phytoplanktonic origin. The POM isotopes composition indicated a maximum δ 13 C value of −21.2‰ close to the river mouth and lowest value (~ −25‰) away from the river influence. The δ 15 N maximum (14.7‰) was observed near the river mouth with lower values (5.8‰) found in deeper waters away from the river mouth. Overall, there was a general decrease of 13 C and δ 15 N values from shallow water to deeper water. There was higher δ 15 N value dispersion (std. Dev. ±3.4‰) compared to δ 13 C values with std. Dev.±1.2‰. These values also varied with seasons, a phenomenon showing significant influence of land run off on the lake elemental distribution, carbon and nitrogen in particular.
PCDD/F and Dioxin-Like PCB determinations in Mtoni estuarine sediments (Tanzania) using the chemically activated luciferase gene expression (CALUX) bioassay
(Canadian Center of Science and Education, 2013-03-19) Mihale, Matobola J.; Croes, Kim; Tungaraza, Clavery; Baeyens, Willy; Van Langenhove, Kersten
Sediments from Mtoni estuary and 2 tributaries, Tanzania, were screened for polychlorinated-p-dibenzodioxins, -dibenzofurans (PCDD/Fs) and dioxin-like PCBs (dl-PCBs) using the chemically activated luciferase gene expression (CALUX) bioassay approach. PCDD/Fs expressed as bio analytical equivalence (BEQ) values ranged from 5.7 ± 1.4 to 39.9 ± 5.8 pg BEQ/g sediment in the wet season and from 14.1 ± 2.0 to 32.8 ± 4.7 pg BEQ/g sediment in the dry season, with higher levels observed in Kizinga River and stations close to the mouth of that river. Dioxin-like PCB levels ranged from 0.21 ± 0.03 to 0.53 ± 0.03 pg BEQ/g sediment in the wet season and from 0.22 ± 0.03 to 0.59 ± 0.04 pg BEQ/g sediment in the dry season. Higher PCDD/F and dl-PCB levels in sediments are probably related to open burning of plastic scraps, household burning of wood or charcoal and traffic related emissions, all of which occur in the Dar es Salaam region. The denser population and the more intense industrial activities in the Kizinga River basin may explain the enhanced PCDD/F and dl-PCB levels observed in the sediments of that river compared to the levels in the Mzinga River basin. A third sampling campaign, including also stations in the downstream estuary, confirmed the enhanced levels in the Kizinga River (maximum of 400 pg-BEQ/g) and also showed that a clear decreasing concentration gradient in the downstream direction exists. It cannot be excluded that the levels of these pollutants in the sediments of the Mtoni estuary pose a threat to the local biological community.
Optimization of Extraction Conditions and Phytochemical Screening of Root Extract of Synadenium glaucescens Pax
(Canadian Center of Science and Education, 2013-10-20) Mabiki, Faith P.; Magadula, Joseph J.; Mdegela, Robinson H.; Mosha, Resto D.
Optimization of extraction conditions and phytochemical screening of the root bark of Synadenium glaucescens were carried out in a stepwise manner in order to obtain the highest yields and the constituents of the extracts. Sequential extraction using Soxhlet method was performed using dichloromethane, hexane and petroleum ether, respectively, each followed by ethanol. Extraction conditions included: running time of 2 to 6 hours, temperature at 25 o C to 95 o C and particle size ranging from 0.4mm to >3mm diameter. Phytochemical screening was done using derivatisation techniques, gas chromatography-mass spectrometry and high performance liquid chromatography. Extraction with dichloromethane followed by ethanol resulted in a higher yield by 25%, within 4 hrs of extraction, particle size of 1mm, at temperatures of 30 o C for dichloromethane and 75 o C for ethanol. Fatty acid analysis indicated absence of free fatty acids in both Dichloromethane and ethanolic extracts. Silylation and Thin Layer Chromatography indicated the presence of non hindered and hindered functionality and the presence of triterpenoids in the dichloromethane extract. Phytochemical screening of the dichloromethane extracts indicated that it is composed of two main triterpenoids that best matched with Lanosterol (42%) and Cycloartenol (31%). Other minor compounds identified through chromatographic analysis were phytol, ergostadiol, hentriacontane, sitastirol aceate, lupeol and hopenone. The ethanolic extracts indicated the presence of polyphenolic compounds.
Influence of different land use types on bird and tree species diversity around lake Victoria basin in Bukoba municipality, Tanzania
(Sokoine University of Agriculture, 2015) Mutalemwa, Regina
Following a notable loss of biodiversity around Lake Victoria Basin in Tanzania, caused by fast population growth and unsustainable land uses, a study aiming at understanding the influence of different land use types on bird and tree species richness, abundance and diversity in Bukoba Municipality was initiated. The choice of the two biota was made based on the fact that avian and tree communities are good indicators of overall biodiversity and environmental decline or recovery. In identifying the types of land uses, two methods were used, which were direct observation and focus group discussion. The types of land use identified were home garden, fishing zone, open grassland, forest reserve and settlement. Bird and tree data collection in all land uses involved two methods, which were transects walk and direct observations. The data collected were about types and number of bird and tree species in each land use type. The data were analyzed by Microsoft excel, PRIMER 6 and Diversity programme 2007. The results showed that the Shannon-Weaver indices of bird diversity for homegarden, fishing zone, open grassland, forest reserve and settlement were 2.855, 2.793, 2.5, 1.791 and 2.054 respectively. The Shannon-Weaver indices of tree diversity for homegarden, fishing zone, open grassland, forest reserve and settlement were found to be 1.973, 0.7857, 1.726, 2.087 and 1.877 respectively. The results further showed that fishing zone land use had high bird diversity, while the highest diversity in tree species was noted in forest reserve land use. Therefore, the study concludes that there is greater variation in species richness between land uses, showing how each land use has an influence on species abundance, richness and diversity in the area. Again, increase in human population was seen as the problem in the maintenance of different land uses. It is recommended that deliberate, steps should be taken to maintain these land uses to their natural state, despite of the increase in human population, so as to maintain the habit of both bird and tree species.
Implementation report of research project: adaptation strategies for challenges associated with climate and ecological changes affecting lake victoria communities
(United National Institute for Training and Research, 2015) Tungaraza, Clavery; Eliapenda, Elisante; Osewe, Kajitanus O.; Palapala, Paul M.
Assessment of sources and transformation of nitrate in groundwater on the slopes of Mount Meru, Tanzania
(Springer, 2015-09-21) Elisante, Eliapenda; Muzuka, Alfred N. N.
The stable isotope compositions of nitrogen-nitrate ( 15 N-NO 3 ) and oxygen-nitrate ( 18 O-NO 3 ), and concentration of nutrients (NO 3 - , NH 4 ? , NO 2 - , PO 43- ) for water samples collected from springs, shallow wells and boreholes during dry and wet seasons were used to inves- tigate sources and biogeochemical transformation of NO 3 - in groundwater along the slopes of Mount Meru. About 80 % of all water sources had nitrate concentration higher than background concentration of 10 mg/l during both seasons, while NH 4 ? and NO 2 - concentrations were very low probably due to nitrification. Concentrations of NO 3 - above 50 mg/l were observed in some water sources. Concentrations of PO 43- in all groundwater sources were very low during the two seasons owing to dilution and adsorption. The d 15 N-NO 3 - for boreholes waters averaged ?11.6 ± 2.1 and ?10.7 ± 2.1 % during dry and wet seasons, respectively. Similarly, the d 18 O-NO 3 - of bore- hole waters for the wet and dry seasons averaged ?5.2 ± 1.3 and ?4.6 ± 1.9 %, respectively. With regard to dug wells, the d 15 N-NO 3 - of well water averaged ?13.3 ± 2.5 and ?12.5 ± 2.3 % during dry and wet seasons, respectively, while the d 18 O-NO 3 - for the wet and dry seasons averaged ?7 ± 2.3 and ?6.4 ± 2.1 %, respectively. The d 15 N-NO 3 - , for springs averaged ?11.2 ± 2.2 % during dry season and ?11.7 ± 3.5 % during wet season whereas the d 18 O-NO 3 - for the wet and dry seasons averaged ?7.3 ± 3.6 and ?5.9 ± 2.6 %, respectively. The isotopic data suggested that the source of NO 3 - in the water sources are dominated by sewage and/or animal manure and to less extent, soil organic N. Few samples collected in close proximity of manure heaps and sanitary facilities had d 15 N values between 16 and 20 %suggesting occurrence of denitrification.
Levels of formaldehyde and acetaldehyde in selected bottled drinking water sold in urban areas in Tanzania
(College of Natural and Applied Sciences (CoNAS) of the University of Dar es Salaam (UDSM), 2016) Lugwisha, E. H. J.; Mahugija, J. A. M.; Mwankuna, C.
The levels of formaldehyde and acetaldehyde in bottled drinking water and the effect of storage time and storage conditions on their levels were determined. A total of 144 samples of six brands of bottled drinking water were purchased from Dar es Salaam, Iringa, Mwanza and Arusha regions in Tanzania. Analysis was performed using HPLC on the 1st day and after 14 and 42 days of storage in a refrigerator, at room temperature and exposure to sunlight. The levels of formaldehyde and acetaldehyde in the refrigerated samples ranged from 2.46 to 19.25 μg/L and from not detected (ND) to 58.70 μg/L, respectively. In samples stored at room temperature, the levels of formaldehyde and acetaldehyde were up to 23.26 μg/L and 36.10 μg/L, respectively. The highest levels of formaldehyde and acetaldehyde in samples exposed to sunlight were 46.0 μg/L and 187.0 μg/L, respectively. The lowest levels of the aldehydes were found in refrigerated samples and the highest levels were in samples exposed to sunlight. The levels of these aldehydes increased with increased storage time. The levels were below the WHO acceptable limits; however, the findings indicate that the levels could be elevated with increased storage time and exposure to sunlight.
Corrosion inhibition of Amino Pentadecylphenols (APPs) derived from Cashew Nut shell liquid on mild steel in Acidic medium
(Scientific Research Publishing Inc., 2016-08) Philip, Joseph Yoeza Naimani; Buchweshaija, Joseph; Mwakalesi, Alinanuswe J.
In this study, corrosion inhibiting properties of amino pentadecylphenols (APPs) derived from Cashew Nut Shell Liquid (CNSL) on mild steel in aerated 0.10 M HCl at 303 K were studied using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements. Both methods indicated the potential of a mixture of amino pentadecyphenols to serve as a corro- sion inhibitor in mild steel in 0.10 M HCl. Corrosion inhibition efficiencies were observed to in- crease with increase in the inhibitor concentration, with maximum corrosion inhibition of about 98% at inhibitor concentration of 600 ppm. The adsorption of the inhibitor on mild steel surface was found to obey Temkin adsorption isotherm, signifying physical adsorption of the inhibitor molecules on mild steel surface.
Optimized HPLC -UV method for separation, detection and quantification of endocrine disrupting estrogens in low quality water
(Canadian Center of Science and Education, 2017) Msigala, S. C.; Mabiki, F. P.; Styrishave, B.; Mdegela, R. H.
Endocrine disrupting estrogens are emerging contaminants in aquatic ecosystems and environment in general. There are no guidelines for routine monitoring of these chemicals, despite the existing evidences of their adverse health effect to living organisms at low concentrations. This study aimed at developing and validating an optimized HPLC-UV method for detection and quantification of estradiol and ethinylestradiol. Isocratic elution was used for separation and detection of ethinylestradiol and estradiol. The mobile phase was applied with A; water B; acetonitrile (50:50) at flow rate of 0.7mL/min and injection volume 10mL. The precision and accuracy of the method were within the acceptable range. Relative standard deviation of peak area for E2 ranged from 1.373 to 3.668%, and for EE2 ranged from 0.829 to 6.495 %. The percentage recovery for E2 ranged from 82.3 to 99.84 %, and for EE2 ranged from 84.6 to 103.52 %. Linearity of the method was realized at range of 2.5 to 50 ng/mL and 100 to 1000 ng/mL for both E2 and EE2. The linear regression coefficients were 0.9979 and 0.9973 for E2 whereas for EE2 were 0.9983 and 0.9976. Limit of detection were found to be 0.05 ng/mL and 0.08 ng/mL for E2 and EE2 respectively. The obtained limits of quantification were 0.18 and 0.28 ng/mL for E2 and EE2 respectively. In untreated sewage the concentrations of E2 and EE2 were 0.28 ng/ml and 0.18 ng/ml respectively. But in subsequent wastewater stabilization ponds the concentrations were below detection limit. Therefore, the optimized HPLC-UV method is suitable for detection and quantification of endocrine disrupting estrogens when a level of pollution is at least 0.15 ng/ml. At low extent of pollution would require use of the method in conjunction with ELISA technique.
Performance of wastewater stabilization ponds in treatment of endocrine disrupting estrogens in Morogoro urban and peri-urban, Tanzania
(International Scholars Journals, 2017) Msigala, S. C.; Mabiki, F. P.; Styrishave, B.; Mdegela, R. H.
The aim of the study was to assess the performance of wastewater stabilization ponds (WSPs) in treatment of endocrine disrupting estrogens particularly estradiol (E2), estrone (E1) and ethinylestradiol(EE2). The study was conducted at Mafisa and Mzumbe wastewater stabilization ponds located in Morogoro Urban and Periurban areas respectively. The endocrine disrupting estrogens in low quality water and sludge were detected and quantified using competitive Enzyme Linked Immunosorbent Assay. The recovery of estrogens in this study ranged from 65% to 90%. The EE2, E1 and E2 were detected in all samples of low quality water and sludge from anaerobic to maturation ponds in both study sites. The overall estrogen reduction at Mafisa was 95.8%, 95.3%, 94.9% for EE2, E1 and E2 respectively. At Mzumbe the overall estrogen reduction was 81.6%, 89.3% and 82.5% for EE2, E1 and E2 respectively. The mean concentrations of estrogens in influent to effluent at Mafisa ranged from 35.6 to 1.5. 60.7 to 2.9 and 85.6 to 4.4 ng/ L for EE2, E1 and E2 respectively. The corresponding mean concentration at Mzumbe WSPs ranged from 25.5 to 2.7, 23.8 to 4.4 and 39.4 to 6.9 ng/L for EE2, E1 and E2 respectively. Sludge from anaerobic pond contained significant high amount of estrogens, whereas in other ponds median concentrations were significant low. The endocrine disrupting estrogens were significantly reduced in the wastewater stabilization ponds.
Pollution by endocrine disrupting estrogens in aquatic ecosystems in Morogoro urban and peri-urban areas in Tanzania
(Academic Journal, 2017) Msigala, S. C.; Mabiki, F. P.; Styrishave, B.; Mdegela, R. H.
This study aimed to assess the extent of pollution of aquatic ecosystems by endocrine disrupting estrogens particularly the ethinylestradiol (EE2), estrone (E2) and estradiol (E1). The study was carried out in Morogoro urban and peri-urban areas. The main sources of fresh water for domestic uses, fishing and agricultural activities in the study areas including the Mindu dam catchment area, Ngerengere and Morogoro Rivers were assessed. The endocrine disrupting estrogens in water samples were identified and quantified using competitive Enzyme Linked Immunosorbent Assay (ELISA) kits. The recovery of estrogens in this study ranged from 65 to 90.22%, the range which is within the acceptable level. The levels of estrogens in Ngerengere River ranged from non-detectable levels to 0.68, 0.03 to 8.42 and 0.05 to 16.97 ng/L for EE2, E2 and E1, respectively. At Mindu Dam the levels ranged from 0.07 to 0.3 ng/L, 0.41 to 2.1 ng/L and 2.6 to 6.5 ng/L for EE2, E2 and E1 respectively. Furthermore, for Morogoro River the levels ranged from undetected to 0.92, 0.34 to 9.53 and 0.17 to 11.49 ng/L for EE2, E2 and E1 respectively. Mean concentrations in control samples and those in upstream and midstream of the rivers were comparable (p > 0.05). But the mean concentrations in downstream portions were significantly higher than those in control samples (p < 0.05). These concentrations however, were below those reported in other studies to cause harmful health effects. Hence, the extent of pollution was not significant enough to cause adverse health effects to aquatic organisms and human.
Assessing significance of community documented climate impacts and adaptation preferences and options in the lake victoria region, Tanzania
(Ethiopian Journal of Environmental Studies & Management, 2017-02-13) Elisante, E.; Tungaraza, C.
The study was conducted in Ukerewe Island in the Lake Victoria, Tanzania in order to ascertain the communities’ awareness on climate change impacts and adaptation/coping strategies. The methodology involved randomly selected 420 people mostly farmers and fishermen who were interviewed and involved in focus groups. It was observed that communities were aware of the changes in climatic parameters consequently impacting their livelihood. The most significant impacts were scarcity of water and poor crop production which received 100% support of the respondents. Other impacts included the change of water quality of the Lake Victoria (94.5%) and loss of biodiversity (35.7%). On the non-climatic factors, the major concern was on population growth (98.3%), loss of soil fertility (96%) and deforestation (84.8%). Of the suggested adaption options, provision of alternative food crops and fertility improvement to increase production were highly supported with highest total score of 48 on an arbitrary total assessment scale of maximum of 50. This was also observed on fish farming activities. The observations highlighted gender-based labour division imbalance where women and children were shown to shoulder the burden. It can be concluded that communities in the Lake Victoria region are affected by multiple impacts related to climate and also those not related to climate. Under various impacts communities set their own coping and adaptation strategies based on importance to livelihood. However, there is a need for proper guidance on how adaptation strategies are being executed.

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