School of Pure and Applied Sciences

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    Analysis of Moss and Topsoil to Monitor Metal Emissions from a Pulp and Paper Mill in Western Kenya
    (2011) Adoli, Florence K; Lalah, Joseph O; Okoth, Alexander O
    The mean concentrations of Zn, Cu, Cd, Cr and FeinmossesaroundWebuyePanPaperfactorywerefound to be significantly higher than in controls taken from Kakamega, indicating atmospheric contribution from the anthropogenic activities within the factory, shown within a radius of 1 km around the factory. The mean concentrations (lg/g dry weight) in the mosses ranged from 60.9–124.5, 22.6–34.2, 13.3–14.7, 20.1–33.3 and 1,822.4– 2,079.2, respectively. The mean concentrations of Pb in mosses sampled from the eastern and western side of the factory were also significantly higher than in controls. The mean concentrations of Zn, Cu, Cd, Cr, Pb and Fe in topsoil samples ranged from 7 (Pb)–2,310 (Fe) mg/kg dry wt, depending on sample means based on site direction, distance from the factory and season. There was no clear variation in metal concentrations in mosses and topsoils with direction from the factory which was consistent with the observed fluctuations in wind direction which changed from south-west in the mornings to north and south-west in the afternoons during sampling.
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    Analysis of Moss and Topsoil to Monitor Metal Emissions from a Pulp and Paper Mill in Western Kenya
    (Springer, 2010-07-05) Lalah, Joseph O.
    The mean concentrations of Zn, Cu, Cd, Cr and Fe in mosses around Webuye Pan Paper factory were found to be significantly higher than in controls taken from Kakamega, indicating atmospheric contribution from the anthropogenic activities within the factory, shown within a radius of 1 km around the factory. The mean concentrations (lg/g dry weight) in the mosses ranged from 60.9–124.5, 22.6–34.2, 13.3–14.7, 20.1–33.3 and 1,822.4– 2,079.2, respectively. The mean concentrations of Pb in mosses sampled from the eastern and western side of the factory were also significantly higher than in controls. The mean concentrations of Zn, Cu, Cd, Cr, Pb and Fe in topsoil samples ranged from 7 (Pb)–2,310 (Fe) mg/kg dry wt, depending on sample means based on site direction, distance from the factory and season. There was no clear variation in metal concentrations in mosses and topsoils with direction from the factory which was consistent with the observed fluctuations in wind direction which changed from south-west in the mornings to north and south-west in the afternoons during sampling.
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    Anthropogenic Sources of Heavy Metals in the Indian Ocean Coast of Kenya
    (Springer Science+Business Media, LLC, 2008-11-28) Lalah, Joseph O.
    Water and surface sediment samples from Rivers Sabaki, Ramisi and Vevesi that flow into the Indian Ocean coast of Kenya were analysed for heavy metals. The sediment concentrations of exchangeable cations (in μg/g) for Co, Cu, Mn, Ni, Pb, Sn and Zn ranged from 0.10 to 506.75 (for Mn at Sabaki), constituting between 2% and 20% of the total metal concentrations obtained by digestion with strong acid. Cu, Mn, Ni, Pb and Zn were more leachable with 0.1 N HCl. The total dissolved metal in water and the total sediment concentrations for Ag, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn and Zn are given in the text. For dissolved metals, the metal/Mn ratios indicated higher concentrations of Ag in Sabaki River, Cd in Ramisi, Ni in Sabaki and Pb in Ramisi, respectively. In sediments, the metal/Mn ratios showed higher enrichment of Ag in Ramisi, Cd in Sabaki and Vevesi, and Zn in Sabaki, respectively. Enrichment factors showed elevated levels of Cd, Pb and Zn in sediment in River Sabaki and River Vevesi that were due to anthropogenic inputs through Athi River. The total dissolved metal concentration ranges for the three rivers were comparable with those ranges reported in rivers in South Africa but the sediment concentrations were below those of rivers in Europe and Asia where anthropogenic addition of some of the toxic elements such as Cu, Pb and Cd is evidently higher.
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    Application of hydrogeochemical modelling in simulating the transportation of elements in fly ash heap under different disposal systems in South Africa
    (2015-07-20) Mbugua, John
    Ash heap modelling of South African fly ash from Tutuka was carried out and the duration of transportation projected for 20 years based on two disposal scenarios, namely; irrigation of ash with rainwater, and irrigation with brines. The hydrogeochemical modeling code, PHREEQC, was applied in the study which gave insights into the speciation, release and transport of elements from the water and brines–fly ash long term interactions. Tutuka ash–water heap model showed a general sharp decrease of total elemental concentrations released during the first 2.5 years simulation as the pH value dropped from 12.6 to 8.7, after which it remained constant and their concentration remained constant up to 20 years. The elements showing this trend included Ca, Mg, Al, Fe, Sr, Zn, Na, K, Li and C(4). Generally, brines caused sharp increase in released concentration of the elements Ca, Mg, S(6) and C(4) for the first 3 years of heap irrigation whereas with water irrigation an opposite trend was observed in which the elemental concentrations decreased. Much of the release chemistry of the elements was closely related to the phase dissolution/precipitation and formation as the major controlling factors. Generally therefore, the modelled leachate quality results revealed that many elements are mobile and move through the ash heap in a progressive leaching pathway. The model could therefore be used to provide reasonable leachate quality from the modelled Tutuka ash heap which may be reaching the ground water. Overall, the ash heap modelling enhanced the understanding of the environmental impacts of ash–water–brines interactions and demonstrated that leachate composition is determined by the following factors; (i) the mass flows from the pores of fly ash, (ii) the surface dissolution of the mineral phases, (iii) the various chemical reactions involved during the ash–brine and ash–water interactions, (iv) the interactions with a gas phase (atmospheric CO2), (v) the composition of the initial fly ash, and (vi) the leachate flow and hydrodynamics as captured in the conceptual model. Further model validation is recommended with lysimeters to quantatively compare the simulated results against the experimental data and improve on the model.
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    Assessment of Polycyclic Aromatic Hydrocarbons in Lates niloticus, Oreochromis niloticus and Rastrineobola argentea as Sources of Human Exposure in Kisumu Bay, Winam Gulf of Lake Victoria
    (2012) Onyango, Alice A; Lalah, Joseph O; Wandiga, Shem O; Gichuki, John
    The concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lates niloticus, Oreochromis niloticus and Rastrineobola argentea from three beaches were assessed to establish whether they are sources of human exposure in Kisumu Bay, Winam Gulf, Lake Victoria, Kenya. O. niloticus had 12 PAHs detected (TPAH 3.93 μg/kg); L. niloticus had 11 (TPAH 3.17 μg/kg). In both cases, the highest and lowest concentrations were Pyrene and Indeno(1,2,3-cd)pyrene, respectively, and the TPAHs were greater than the 2 μg/kg limit allowed by the European Commission although individually they were lower. R. argentea had 2 PAHs (TPAH 0.035 μg/kg). PAH pollution in the Winam Gulf, a potential source of exposure to human through contaminated fish, should be mitigated and safe management practices that reduce PAH levels should be adopted.
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    Astronomy in the cultural heritage of African societies
    (2006) Baki, Paul
    The African perspectives of astronomy are explored from the point of view of using indigenous knowledge of the night sky for purposes of addressing local challenges such as food insecurity and periodic natural weather phenomena such as droughts and floods. The local ethnic groups use stellar positions, and plant and animal behaviour changes for purposes of forecasting the weather and climate for the coming seasons. These traditional indicators give rise to an interdisciplinary discourse that could benefit the community in environmental protection measures and boost the tourism industry in some countries in Africa
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    Behavior of pesticide residues in agricultural soil and adjacent River Kuywa sediment and water samples from Nzoia sugarcane belt in Kenya
    (Springer, 2012) Muendo, Boniface M; Lalah, Joseph O; Getenga, Zachary M
    An inventory survey conducted to determine pesticide usage in a sub-catchment of the Nzoia sugarcane belt found a variety of pesticides used in the sub-catchment, which are reported in this paper. Analysis of soil samples from seven fallow experimental field plots left uncultivated for various periods from 3 to 96 months after cultivation with pesticide application indicated persistence of high concentrations of pesticide residues in the soil, with estimated soil half-lives (in years) ranging from 0.72 to 57.75 for organochlorines and from 1.13 to 8.25 for herbicides. The mean water concentrations (in μg/L) of the pesticide residues in River Kuywa, which flows through the Nzoia Nucleus Estate sugarcane farms, ranged from 0.12 (lindane) to 1.36 (p,p′-DDT) for organochlorines and from 0.14 (atrazine) to 1.75 (diuron) for herbicides during the heavy rains period in August 2008 while the mean sediment concentrations (in μg/g) ranged from 0.28 (lindane) to 1.87 (endrin) for organochlorines and 0.39 (hexazinone) to 4.61 (alachlor) for herbicides. The mean concentrations of residues in water during the light rain period in December 2008 ranged from 0.17 (p,p′-DDT) to 0.71 (aldrin) for organochlorines and 0.01 (atrazine) to 1.74 (alachlor) for herbicides while the sediment concentrations ranged from 0.38 (p,p′-DDT) to 1.145 (aldrin) for organochlorines and 0.74 (atrazine) to 1.98 (alachlor) for herbicides. Although DDT, aldrin, dieldrin, and endrin were not reported in the survey, their presence in the fallow experimental field plot soils and in River Kuywa water and sediment could indicate previous application, lack of recorded data or illegal usage since 1997 when they were banned. Notably, the concentrations of alachlor, diuron, cypermethrin, and hexazinone in the water column were substantial indicating their extensive usage and residual persistence in the sub-catchment, with subsequent wash-off and leaching into River Kuywa. The concentration levels of some of the individual pesticides exceeded the EU limit requirements for drinking water and indicated potential risk to humans and cattle if the water is used without treatment.
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    The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L.
    (2003) Lalah, Joseph O.; Behechti, Akbar; Severin, Gabriele F; Lenoir, Dieter; Günther, Klaus; Kettrup, Antonius; Schramm, Karl-Werner
    A single branched isomer of p-nonylphenol, 4(3′,6′-dimethyl-3′-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 μg/L (range: 92–116 μg/L) in water at 19°C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 μg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3′,6′-dimethyl-3′-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with β-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.
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    Carbofuran and its Toxic Metabolites Provide Forensic Evidence for Furadan Exposure in Vultures (Gyps africanus ) in Kenya
    (2010) Otieno, Peter O; Lalah, Joseph O; Virani, Munir; Jondiko, Isaac O; Schramm, Karl-Werner
    Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl – 0.07 (carbofuran), bdl – 0.499 (3-ketocarbofuran) and 0.013–0.147 (3-hydroxycarbofuran) in beaks, bdl–0.65 (carbofuran), 0.024–0.190 (3-ketocarbofuran) and 0.017–0.098 (3-hydroxycarbofuran) in feet, 0.179–0.219 (3-ketocarbofuran) and 0.081–0.093 (3-hydroxycarbofuran) in crop content, 0.078–0.082 (3-ketocarbofuran) and 0.091–0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006–0.014 (carbofuran), 0.590–1.010 (3-ketocarbofuran) and 0.095–0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran.
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    Carbofuran use and abuse in Kenya: residues in soils, plants, water courses and the African white-backed vultures (Gyps africanus ) found dead
    (2011) Otieno, Peter O; Lalah, Joseph O; Virani, Munir; Jondiko, Isaac O; Schramm, Karl-Werner
    The increasing number of incidences of alleged wildlife poisoning with Furadan in Kenya has sparked off a strong lobby fronted by wildlife conservationists against Furadan use in the country and prompted this study. The worst-case scenario was in 2004 in Athi River, where a massive number of 187 African white-backed vultures (Gyps africanus) and hyenas were found dead at a spot where poisoning was suspected to have occurred through a Furadan-laced camel carcass bait. This study was initiated by the Peregrine Fund—Africa Project, and the objective was to provide evidence for Furadan exposure, its misuse and involvement in vulture poisoning and potential impact on areas near two wildlife conservancies in two most affected districts. The study found evidence for ready availability of Furadan 5G in local veterinary retail shops and its illegal misuse by pastoralists and farmers against wildlife to protect their animals and crops. Analysis of soil, water and plants taken from the farms and water sources by high-perfomance liquid chromatography (HPLC) and gas liquid chromatography–mass spectrometry (GC–MS) found residues of carbofuran, 3-hydroxycarbofuran and 3-ketocarbofuran, indicating that Furadan was used extensively in farming causing residual environmental distribution and contamination and posing risks to small birds and mammals. Forensic analysis of residues in beaks, feet and crop content of the dead vultures as well as in a laced camel carcass bait and soil samples from one site of poisoning also showed carbofuran and its two metabolites supporting allegations of Furadan involvement in wildlife poisoning and high-mortality cases of African white-backed vultures (Gyps africanus) in Kenya.
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    Comparison of GPS TEC measurements with IRI-2007 TEC prediction over the Kenyan region during the descending phase of solar cycle 23
    (Elsevier, 2012) Olwendo, OJ; Baki, P; Cilliers, PJ; Mito, C; Doherty, P
    This paper presents an analysis of the Total Electron Content (TEC) derived from the International GNSS Service receiver (formerly IGS) at Malindi (2.9°S, 40.1°E), Kenya for the periods 2004–2006 during the declining phase of solar cycle 23. The diurnal, monthly and seasonal variations of the TEC are compared with TEC from the latest International Reference Ionosphere model (IRI-2007). The GPS–TEC exhibits features such as an equatorial noon time dip, semi-annual variations, Equatorial Ionization Anomaly and day-to-day variability. The lowest GPS–TEC values are observed near the June solstice and September equinox whereas largest values are observed near the March equinox and December solstice. The mean GPS–TEC values show a minimum at 03:00 UT and a peak value at about 10:00 UT. These results are compared with the TEC derived from IRI-2007 using the NeQuick option for the topside electron density (IRI–TEC). Seasonal mean hourly averages show that IRI-2007 model TEC values are too high for all the seasons. The high prediction primarily occur during daytime hours till around midnight hours local time for all the seasons, with the highest percentage deviation in TEC of more 90% seen in September equinox and lowest percentage deviation in TEC of less than 20% seen in March equinox. Unlike the GPS–TEC, the IRI–TEC does not respond to geomagnetic storms and does overestimate TEC during the recovery phase of the storm. While the modeled and observed data do correlate so well, we note that IRI-2007 model is strongly overestimating the equatorial ion fountain effect during the descending phase of solar cycle, and this could be the reason for the very high TEC estimations.
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    Declining commercial fish catches in Lake Victoria's Winam Gulf: The importance of restructuring Kenya's aquaculture programme
    (2014) Omwoma, Solomon; Owuor, Philip O; Ongeri, David MK; Umani, Moses; Lalah, Joseph O; Schramm, Karl-Werner
    The total weight of commercial fish (metric tons) caught in the Winam Gulf area of Lake Victoria in Kenya declined from 3300 mt to 760 mt between 1995 and 2009. Associated with this decline, and ranked in descending order, the species richness of the commercial fish catch was limited to seven major groups (Rastrineobola argentea; Lates niloticus; Protopterus aethiopicus; Labeo victorianus; Haplochromis species; Clarias gariaepinus; Bagrus domac). Numerous hypotheses ranging from eutrophication, inadequate control of the exotic water hyacinth and overfishing were advanced to explain this decline. The Kenyan government, working in partnership with international organizations, implemented multiple restoration and management programmes in response, including aquaculture. Unfortunately, success for this implemented programme has been very limited because important socio-economic driving factors were overlooked. To provide a better understanding of the issues, 150 members of the Winam Gulf fishing community, ranging in age from 20 to 40 years, were surveyed. The results of this survey identified poverty and inadequate education as two major issues requiring substantial attention. The survey also suggested that if societal changes are to occur, it will rest upon changing the beliefs of the youth in the Winam Gulf area. Restructuring Kenya's aquaculture programme, with a focus on the youth, provides a pathway for increasing the literacy level of the community, as well as for reducing poverty.
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    Developing Global Leaders for Research, Regulation, and Stewardship of Crop Protection Chemistry in the 21st Century
    (2015) Unsworth, John B; Corsi, Camilla; Van Emon, Jeanette M; Farenhorst, Annemieke; Hamilton, Denis J; Howard, Cody J; Hunter, Robert; Jenkins, Jeffrey J; Kleter, Gijs A; Kookana, Rai S; Lalah, Joseph O; Leggett, Michael; Miglioranza, Karina S. B; Miyagawa, Hisashi; Peranginangin, Natalia; Rubin, Baruch; Saha, Bipul; Shakil, Najam A
    To provide sufficient food and fiber to the increasing global population, the technologies associated with crop protection are growing ever more sophisticated but, at the same time, societal expectations for the safe use of crop protection chemistry tools are also increasing. The goal of this perspective is to highlight the key issues that face future leaders in crop protection, based on presentations made during a symposium titled “Developing Global Leaders for Research, Regulation and Stewardship of Crop Protection Chemistry in the 21st Century”, held in conjunction with the IUPAC 13th International Congress of Pesticide Chemistry in San Francisco, CA, USA, during August 2014. The presentations highlighted the fact that leaders in crop protection must have a good basic scientific training and understand new and evolving technologies, are aware of the needs of both developed and developing countries, and have good communication skills. Concern is expressed over the apparent lack of resources to meet these needs, and ideas are put forward to remedy these deficiencies
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    Dioxin-like PCBs and PCDD/Fs in surface sediments near the shore of Winam Gulf, Lake Victoria
    (Elsevier, 2015) Omwoma, Solomon; Lalah, Joseph O; Virani, Munir; Schramm, Karl-Werner; Henkelmann, Bernhard
    Winam Gulf of Lake Victoria is considered to be contaminated with toxic chemicals emanating from anthropogenic activities, especially near large industrial towns such as Kisumu. This has recently caused concerns about its water quality and impact on aquatic organisms and human beings. This study was justified by the need to generate baseline concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in surface sediment from selected sites in the lake and determine the influence of activities on their concentrations and potential risks to fish-eating birds living near the lake. Surface sediments (<30 cm) from three different fish landing beaches, located 200 m from the shore of Winam Gulf of Lake Victoria near Kisumu city, Homa Bay and Mbita (control) towns, were analysed. The total mean concentrations (in pg g−1 dry wt) were found to range from 17.4–812 (Σdl-PCBs), 36.6–813 (ΣPCDDs) and 1.45–46.4 (ΣPCDFs). The calculated Toxic Equivalents (TEQWHO(2005)) ranged from 0.001–0.43 (Σdl-PCBs) and 0.09–31 (ΣPCDD/Fs). The fish landing beaches at Kisumu city were found to be contaminated with respect to dl-PCBs and dioxins, followed by Homa Bay and Mbita. The relatively high levels of octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) influenced the TEQ and the ΣPCDFs/ΣPCDDs ratios indicated chemical processes as partial sources of the dioxins. The levels of contaminants obtained in this study showed potential exposure to aquatic organisms and fish eating birds through food chain transfer
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    The dissipation of hexazinone in tropical soils under semi-controlled field conditions in Kenya
    (2009) Lalah, Joseph O; Muendo, Bonface M.; Getenga, Zachary M
    The dissipation of hexazinone (Velpar) in two tropical soil types in Kenya was studied under field and semi-controlled conditions for a period of 84 days. The dissipation was found to be very rapid and this could be attributed to adverse weather conditions including high initial rainfall as well as to low soil-organic-matter content, volatilization, surface run-off and biodegradation. The DT50 values of dissipation obtained by first order kinetics were 20 days and 21.3 days in clay and loam soil types, respectively. The influence of bargasse compost (1000 μg/g dry soil) was also studied and was found to enhance dissipation to some extent, giving DT50 values of 18 days and 18.3 days in clay and loam soil types, respectively.
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    The effect of boiling on the removal of persistent malathion residues from stored grains
    (Elsevier, 2002) Lalah, Joseph O; Wandiga, Shem O
    This study aimed at finding the fate of malathion in maize grains and beans stored in a tropical laboratory for 12 months at temperatures of 20–24°C, relative humidity of 42–80% and grain moisture contents of 11.7–12.5% in maize grains and 14.1–15.3% in beans. Malathion and its degradation products malaoxon, malathion α-monocarboxylic acid and β-monocarboxylic acid were found in stored maize grains and beans treated with a mixture of pure radiolabelled malathion and 2% malathion dust after 12 months of storage. A significant percentage of these residues were removed from the grains by cooking in boiling water. Though malathion and its polar metabolites, malathion α- and malathion β-monocarboxylic acids were completely eliminated by boiling, malaoxon was still detected in quite high quantities in the solvent extracts of cooked beans and maize. Addition of NaCl to the grains increased the rate of removal of the residues from both maize grains and beans by boiling water. The data obtained clearly showed a distinction in persistence, distribution and metabolism of malathion between the two types of crop, indicating also that more adverse windy, humid and hot tropical conditions contributed to higher rates of metabolism and loss of the pesticide from the grains. The accuracy and ease of using radiolabelled malathion in investigating its fate and behaviour in the two matrices is shown in this study.
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    The Effect of Local Cooking Methods on Polycyclic Aromatic Hydrocarbons (PAHs) Contents in Beef, Goat Meat, and Pork as Potential Sources of Human Exposure in Kisumu City, Kenya
    (Taylor & Francis Group, LLC, 2012-11-13) Lalah, Joseph O.
    Roasted meat is known to be a major source of human exposure to PAHs. The contribution of direct-heat charcoal-roasted, electric- oven grilled, and shallow-pan fried meat to human exposure in Kisumu City was not known although the three modes of cooking meat are very prevalent. This study analyzed the concentrations of the PAHs in raw beef, goat meat, and pork, investigated the effect of direct-heat charcoal roasting, electric-oven grilling, and shallow-pan frying on these concentrations, and compared their concentration levels with international standards for foods in order to assess the potential risks to consumers. Samples were taken from three popular meat-roasting hotels within Kisumu City, Kenya. Extraction of PAHs was done using liquid-liquid partition after saponification with alcoholic potassium hydroxide followed by clean-up on a silica gel column and final analysis by gas chromatography-mass spectrometry (GC-MS). Roasting and shallow-pan frying introduced new PAHs and significantly (P ≤ 0.05) increased the concentrations of those existing in raw meat. Direct-heat charcoal roast beef had 5 new PAHs and a total mean PAH content of 17.88 μg/kg, compared with a mean of 1.39 μg/kg for raw beef, with the potent dibenz(a,h)anthracene also being detected. Direct-heat charcoal roasted goat meat had three new PAHs and a total mean PAH content of 4.77 μg/kg, compared with a mean of 2.13 μg/kg in raw meat, with the potent benzo(a)pyrene concentration being 8.84% of the total mean PAH. Fried pork had 7 new PAHs and a total mean PAH content of 3.47 μg/kg, compared with a mean total of 0.17 μg/kg, detected in the raw meat. Roast beef had the highest individual PAH concentration (5.03 μg/kg) and highest total PAHs concentration (17.88 μg/kg), both being higher than acceptable EU limits. The PAHs from local raw and cooked meat were characterized and quantified for the first time in Kisumu City and the study therefore provided the needed baseline data on PAHs in raw and cooked meat
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    Effects of a Branched p-Nonylphenol Isomer (4(3 -,6 -dimethyl-3 -heptyl)-phenol) on Embryogenesis in Lymnae stagnalis L.
    (2015-05-19) Lalah, Joseph O.; Severin, G. F.
    The tertiary branched alkyl-chain isomers of p-nonylphenol (NP) are perceived to have more estrogenic potency than its constituent secondary and primary straight alkyl-chain isomers. Investigations with single tertiary branched isomers ofNP can therefore contribute toward the elucidation ofthe mechanisms oftoxicity and estrogenicity of NP. A single tertiary branched alkyl-chain isomer (4(3 -,6 - dimethyl-3 -heptyl)-phenol) was used in studies to determine its effects on embryonic growth and mortality in Lymnaea stagnalis L. Egg masses were exposed to the test compound for 20 days in a static waterborne-exposure regime with an average NP concentration of105 lg/L and water temperature range of18–20 C. Observations were made under a microscope and pictures were taken with a digital camera to determine the various developmental stages ofgrowth, the duration ofgrowth in each stage, embryo hatchability, and embryo mortality. The isomer was found to cause significant delay in all stages ofgrowth and more significantly in the Morula and Veliger stages. An increase in embryo mortality, from the third day until the end ofthe experiment, was observed in exposed egg masses compared to controls. The hatching success of embryos was also significantly reduced by exposure, with 81% hatchability in exposed egg masses compared to 93% in the controls, after 18 days of continuous exposure. The encapsulating jelly strand that completely covers the rows ofegg masses may have prevented the isomer residues from effectively penetrating into the embryos as shown by the observed low bioconcentration factors of the isomer in egg masses during exposure, resulting in unexpectedly lower observed estrogenic effects. However, this factor was not investigated. In vivo biotransformation ofsome ofthe residues of the isomer into catechol metabolites by the embryos during exposure could also result in the reduction ofits estrogenic potential. To understand more fully the extent of toxicity and estrogenicity ofthis isomer, in vitro estrogenic assays are recommended. It would also be necessary to investigate its estrogenic effects on embryo development after in vivo maternal exposure.
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    Effects of faujasite X and Y zeolites on the 1,1,1-trichloro-2,2’ bis(p-chlorophenyl)ethane (DDT) degradation during water purification
    (2013) Kowenje, Chrispin Ounga; Osewe, Elly Tetty; Lalah, Joseph O
    The ability of zeolites to abstract and denature organochloride pesticides finds application in water purification practices. In this study, activated faujasite X and Y zeolites were separately exposed to 1, 2 and 4 ppm concentrations of 1,1,1-trichloro-2,2’ bis(p-chlorophenyl) ethane (dichloro dipheny trichloroethane - DDT) water solutions. For the 1 ppm DDT solutions, the resultant degradation products and residual DDT were minimal with concentrations in zeolite treatments reducing to below detection limit (0.005 ppm) in about 2 hours. In addition, the rate of dissipation was found to somewhat depend on the levels of DDT concentration and the type of zeolite used. The main degradation product in samples exposed to faujasite X was dichloro dipheny dichloroethylene (DDE) whereas in the faujasite Y exposed samples, both the DDE and dichloro diphenyl dichloroethane (DDD) were obtained.
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    The Effects of Mn2+, Ni2+, Cu2+, Co2+ and Zn2+ Ions on Pesticide Adsorption and Mobility in a Tropical Soil
    (Springer, 2009-05) Lalah, Joseph. O.; Njogu, S. N.; Wandiga, S. O.
    The adsorption behaviour of DDT in a tropical silt-clay soil from Kenya showed that addition of increasing metal ion concentrations from 10 to 100 lg/g of soil, reduced the % DDT adsorption in the soil by factors ranging from 6.1% to 15.4% depending on the type of metal ion. The inhibition of adsorption by metal ions was most observed in the lower ranges of metal ion concentrations in soil, i.e. up to 100 lg/g, beyond which additional increase in metal ion concentration did not result in any further increase in % adsorption. In the standard adsorption test procedure with different soil samples saturated with 100 lg/g of metal ions, the rate of adsorption of the pesticide varied with the type of metal ion and the equilibrium maximum adsorption of DDT was lowered with addition of metal ions, with the % adsorption of 78.4% (control) being reduced to lower values in the range of 67%–77.4%, depending on the type of metal ion. The data for control and samples fitted well into the Freundlich adsorption model and showed that addition of metal ions lowered the Kf values compared with control. The results suggested that in the natural soil–water environments where there was no disturbance, aggregation of humic substances-pesticide molecule complexes altered the observed lowering of adsorption caused by inhibition by metal ions, and enhanced binding to solid soil phase occurred instead. In the leaching experiments, DDT was found to leach more extensively in soils with lower