In this study, the concentration of some toxic metals in different parts of end-of-life mobile ph... more In this study, the concentration of some toxic metals in different parts of end-of-life mobile phones was assessed. Twenty end-of-life mobile phones of different brands and countries of origin, which were widely in use up to the year 2011, were collected from phone repair workshops in Lagos, Nigeria. The collected mobile phones were disassembled into the phone screens, printed wiring boards, plastic casings and batteries. Disassembled parts were individually milled and pulverized, and digested using HCl, HNO3 and H2O2. Flame atomic absorption spectrometry was used to quantify some toxic metals (Pb, Cd and Ni) in the digested samples, and the determined concentrations were compared with permissible limits. The average metals concentration in the disassembled parts followed the order: printed wiring boards > batteries > plastic casings > phone screens. The concentrations of Pb and Ni exceeded their toxicity threshold limit concentration in printed wiring boards, while Ni exce...
In this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and... more In this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and Mn), and the overall water quality from Bomadi Creek in the Niger Delta of Nigeria were assessed over two seasons. Water samples were collected from designated areas along the course of the river and were prepared for analysis by standard procedures. The ranges of the mean values for some water quality indicators were found to be as follows: pH: 7.40–8.17, turbidity (NTU): 20.5–42.3, total dissolved solids (mg L−1): 27.5–44.7, total suspended solids (mg L−1): 34.1–61.7, dissolved oxygen (mg L−1): 3.07–6.53, biochemical oxygen demand (mg L−1): 0.13–2.77, total hardness (mg L−1): 28.3–60.0, and nitrate (mg L−1): 0.37–0.92. Only the turbidity values exceeded the permissible limit of 5 NTU. The concentration ranges (mg L−1) for the six metal ions determined were: Pb: 0.01–0.02, Cd: 0.01–0.03, Zn: 0.1–0.3, Cu: 0.03–0.07, Fe: 0.6–0.9, and Mn: 0.01–0.05. There were no significant variations in...
Journal of Environmental Exposure Assessment, 2022
In this study, five surface water and sediment samples were collected from five different points ... more In this study, five surface water and sediment samples were collected from five different points along the course of the Udu River, Niger Delta, Nigeria, which were near the human population. Water samples were liquid-liquid extracted with dichloromethane in a separatory funnel, while sediment samples were Soxhlet extracted using a mixture of acetone, dichloromethane, and n-hexane. Quantification of polychlorinated biphenyls (PCBs) in the extracts was done using gas chromatography-mass spectrometry. The ecological risk of PCBs was assessed by comparing the determined PCB concentrations with established guideline values, while health risk was evaluated using non-cancer and total cancer risk models. From the results obtained, only one congener (PCB-167) was present in water samples, with concentrations ranging from 20-1860 ng L-1. For sediment samples, 28 congeners were detected. The concentration of Ʃ28PCBs and the 12 dioxin-like PCBs (dl-PCBs) ranged from 5.34-16.1 and 1.07-5.36 ng g-1, respectively. The toxicity equivalence values for dl-PCBs varied from 0.0065-0.018. Compared to guideline values for both water and sediment, the PCB concentration obtained in this study does not pose any ecological risk at all except for one sampled point. Similarly, the hazard index values for non-cancer risk evaluation were < 1 at all but one point, while total cancer risk values were between 1 × 10-6 and 1 × 10-4 at all but one sampling point, indicating no potential risk of developing cancer associated with PCBs in water and sediments of the Udu River.
In this study, the silver extraction potential from waste x-ray films using sodium hydroxide and ... more In this study, the silver extraction potential from waste x-ray films using sodium hydroxide and nitric acid was studied. Sodium hydroxide and nitric acid of different concentrations were used as stripping solutions to determine the optimum leaching concentration. Optimum leaching time and leaching temperature were also investigated by varying the time and temperatures, respectively. The stripped solutions were analysed for silver concentration using Flame Atomic Absorption Spectrophotometer. Results obtained revealed that, for sodium hydroxide stripping, 26.6 mg kg−1 of silver ion was obtained at an optimum leaching concentration, time and temperature of 1.5 M, 900 minutes and 30 °C. For nitric acid stripping, a maximum concentration of 9830.6 mg kg−1 was obtained at optimum concentration, time and temperature of 4 M, 1,440 minutes and 30 °C. The result revealed that the concentration of leaching agent was a significant factor affecting silver recovery, with nitric acid possessing ...
In this study, five surface water and sediment samples were collected from five different points ... more In this study, five surface water and sediment samples were collected from five different points along the course of the Udu River, Niger Delta, Nigeria, which were near the human population. Water samples were liquid-liquid extracted with dichloromethane in a separatory funnel, while sediment samples were Soxhlet extracted using a mixture of acetone, dichloromethane, and n-hexane. Quantification of polychlorinated biphenyls (PCBs) in the extracts was done using gas chromatography-mass spectrometry. The ecological risk of PCBs was assessed by comparing the determined PCB concentrations with established guideline values, while health risk was evaluated using non-cancer and total cancer risk models. From the results obtained, only one congener (PCB-167) was present in water samples, with concentrations ranging from 20-1860 ng L-1. For sediment samples, 28 congeners were detected. The concentration of Ʃ28PCBs and the 12 dioxin-like PCBs (dl-PCBs) ranged from 5.34-16.1 and 1.07-5.36 ng ...
American Journal of Agricultural Science, Engineering, and Technology
The concentration of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in soil, and their ... more The concentration of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in soil, and their bioaccumulation in Lumbricus terrestris in areas around Kolo Creek, Niger Delta, Nigeria were evaluated in this study. 12 soil samples were collected from 4 sites, while Lumbricus terrestris were also collected from areas where soil samples were obtained. Toxic metals were extracted using aqua regia and quantified with a flame atomic absorption spectrophotometer. Extraction of PAHs was achieved by liquid-liquid soxhlet extraction, and quantified with a gas chromatograph-mass spectrometer. The bioaccumulation factor (BAF) for both toxic metals and PAHs were calculated. The results obtained in this study showed that the concentration of all studied toxic metals were within their respective regulatory limits in soil. The BAF for all toxic metals were less than 1 in all sites, indicating minimal bioaccumulation in Lumbricus terrestris. The Ʃ16 PAHs ranged from 7.30 to 77.7 mg kg-1 and 1.10 t...
In this study, the concentration, distribution, ecological and health risk assessment of polychlo... more In this study, the concentration, distribution, ecological and health risk assessment of polychlorinated biphenyls (PCBs) in water and sediment samples from Udu River, Niger Delta Nigeria, was assessed. Water and sediment samples were collected at five different points along the course of the River, which were in proximity to human population. Water samples were liquid-liquid extracted using a mixture of n-hexane and dichloromethane, while sediment samples were soxhlet extracted using acetone/dichloromethane/n-hexane mixture. Extracted PCB congeners were quantified using a gas chromatograph-mass spectrometer. The results revealed that only PCB-167 was detected in water samples, with concentrations ranging from 0.02–1.86 mg L − 1. For sediment samples, the concentration of Ʃ29PCBs ranged from 5.34 to 16.1 ng g − 1. The determined PCB concentrations in both water and sediment samples were within regulatory limits. The concentration of dioxin-like PCBs (dl-PCBs) ranged from 1.07–5.36 n...
Landfills remains an important component in waste management as it deals with municipal solid was... more Landfills remains an important component in waste management as it deals with municipal solid waste directly and complements alternative waste management technologies, which in themselves give rise to residues that require disposal ultimately via landfill. As an assessment study, the work was carried out by visitation to existing dumpsites to obtain needed data and information through the instrumentation of a checklist, interviews, questionnaire and focus group discussions. Stratified random sampling was also used to provide appropriate representation of the societal classes in the population across the 25 Local Government Areas in the State. Results showed that most solid waste collected are deposited in open dumpsites/ landfills on the outskirts of urban areas thereby forming breeding sites for disease vectors and polluting the environment and plausible recommendations for improved waste and environmental management in the State.
The concentrations and potential human health risks through dietary ingestion of PCBs in canned s... more The concentrations and potential human health risks through dietary ingestion of PCBs in canned sardines collected from the Nigerian market were determined. The results shows that the total PCBs concentrations varied from <LOD to 668 ng g−1. The composition of PCBs in the canned sardines followed the order: Penta-PCBs > Hexa-PCBs > Tetra-PCBs > Di-PCB > Deca-PCB > Tri-PCBs > Hepta-PCBs > Octa-PCB. The estimated daily intake for total PCBs ranged from <LOD to 926 ng kg−1 bw day−1 and < LOD to 232 ng kg−1 bw day−1 for child and adult exposures respectively. The TEQs values of the dl-PCBs indicated that these canned sardines are unsafe for consumption. The hazard index and total cancer risk values in 53% of the canned sardines were greater than 1 and 1 × 10−6 respectively indicating that there are adverse non-carcinogenic and carcinogenic risks associated with human consumption of these canned sardines.
Cathode ray tubes are image display units found in computer monitors and televisions. In recent y... more Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelti...
In this study, the concentration of some toxic metals in different parts of end-of-life mobile ph... more In this study, the concentration of some toxic metals in different parts of end-of-life mobile phones was assessed. Twenty end-of-life mobile phones of different brands and countries of origin, which were widely in use up to the year 2011, were collected from phone repair workshops in Lagos, Nigeria. The collected mobile phones were disassembled into the phone screens, printed wiring boards, plastic casings and batteries. Disassembled parts were individually milled and pulverized, and digested using HCl, HNO3 and H2O2. Flame atomic absorption spectrometry was used to quantify some toxic metals (Pb, Cd and Ni) in the digested samples, and the determined concentrations were compared with permissible limits. The average metals concentration in the disassembled parts followed the order: printed wiring boards > batteries > plastic casings > phone screens. The concentrations of Pb and Ni exceeded their toxicity threshold limit concentration in printed wiring boards, while Ni exce...
In this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and... more In this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and Mn), and the overall water quality from Bomadi Creek in the Niger Delta of Nigeria were assessed over two seasons. Water samples were collected from designated areas along the course of the river and were prepared for analysis by standard procedures. The ranges of the mean values for some water quality indicators were found to be as follows: pH: 7.40–8.17, turbidity (NTU): 20.5–42.3, total dissolved solids (mg L−1): 27.5–44.7, total suspended solids (mg L−1): 34.1–61.7, dissolved oxygen (mg L−1): 3.07–6.53, biochemical oxygen demand (mg L−1): 0.13–2.77, total hardness (mg L−1): 28.3–60.0, and nitrate (mg L−1): 0.37–0.92. Only the turbidity values exceeded the permissible limit of 5 NTU. The concentration ranges (mg L−1) for the six metal ions determined were: Pb: 0.01–0.02, Cd: 0.01–0.03, Zn: 0.1–0.3, Cu: 0.03–0.07, Fe: 0.6–0.9, and Mn: 0.01–0.05. There were no significant variations in...
Journal of Environmental Exposure Assessment, 2022
In this study, five surface water and sediment samples were collected from five different points ... more In this study, five surface water and sediment samples were collected from five different points along the course of the Udu River, Niger Delta, Nigeria, which were near the human population. Water samples were liquid-liquid extracted with dichloromethane in a separatory funnel, while sediment samples were Soxhlet extracted using a mixture of acetone, dichloromethane, and n-hexane. Quantification of polychlorinated biphenyls (PCBs) in the extracts was done using gas chromatography-mass spectrometry. The ecological risk of PCBs was assessed by comparing the determined PCB concentrations with established guideline values, while health risk was evaluated using non-cancer and total cancer risk models. From the results obtained, only one congener (PCB-167) was present in water samples, with concentrations ranging from 20-1860 ng L-1. For sediment samples, 28 congeners were detected. The concentration of Ʃ28PCBs and the 12 dioxin-like PCBs (dl-PCBs) ranged from 5.34-16.1 and 1.07-5.36 ng g-1, respectively. The toxicity equivalence values for dl-PCBs varied from 0.0065-0.018. Compared to guideline values for both water and sediment, the PCB concentration obtained in this study does not pose any ecological risk at all except for one sampled point. Similarly, the hazard index values for non-cancer risk evaluation were < 1 at all but one point, while total cancer risk values were between 1 × 10-6 and 1 × 10-4 at all but one sampling point, indicating no potential risk of developing cancer associated with PCBs in water and sediments of the Udu River.
In this study, the silver extraction potential from waste x-ray films using sodium hydroxide and ... more In this study, the silver extraction potential from waste x-ray films using sodium hydroxide and nitric acid was studied. Sodium hydroxide and nitric acid of different concentrations were used as stripping solutions to determine the optimum leaching concentration. Optimum leaching time and leaching temperature were also investigated by varying the time and temperatures, respectively. The stripped solutions were analysed for silver concentration using Flame Atomic Absorption Spectrophotometer. Results obtained revealed that, for sodium hydroxide stripping, 26.6 mg kg−1 of silver ion was obtained at an optimum leaching concentration, time and temperature of 1.5 M, 900 minutes and 30 °C. For nitric acid stripping, a maximum concentration of 9830.6 mg kg−1 was obtained at optimum concentration, time and temperature of 4 M, 1,440 minutes and 30 °C. The result revealed that the concentration of leaching agent was a significant factor affecting silver recovery, with nitric acid possessing ...
In this study, five surface water and sediment samples were collected from five different points ... more In this study, five surface water and sediment samples were collected from five different points along the course of the Udu River, Niger Delta, Nigeria, which were near the human population. Water samples were liquid-liquid extracted with dichloromethane in a separatory funnel, while sediment samples were Soxhlet extracted using a mixture of acetone, dichloromethane, and n-hexane. Quantification of polychlorinated biphenyls (PCBs) in the extracts was done using gas chromatography-mass spectrometry. The ecological risk of PCBs was assessed by comparing the determined PCB concentrations with established guideline values, while health risk was evaluated using non-cancer and total cancer risk models. From the results obtained, only one congener (PCB-167) was present in water samples, with concentrations ranging from 20-1860 ng L-1. For sediment samples, 28 congeners were detected. The concentration of Ʃ28PCBs and the 12 dioxin-like PCBs (dl-PCBs) ranged from 5.34-16.1 and 1.07-5.36 ng ...
American Journal of Agricultural Science, Engineering, and Technology
The concentration of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in soil, and their ... more The concentration of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in soil, and their bioaccumulation in Lumbricus terrestris in areas around Kolo Creek, Niger Delta, Nigeria were evaluated in this study. 12 soil samples were collected from 4 sites, while Lumbricus terrestris were also collected from areas where soil samples were obtained. Toxic metals were extracted using aqua regia and quantified with a flame atomic absorption spectrophotometer. Extraction of PAHs was achieved by liquid-liquid soxhlet extraction, and quantified with a gas chromatograph-mass spectrometer. The bioaccumulation factor (BAF) for both toxic metals and PAHs were calculated. The results obtained in this study showed that the concentration of all studied toxic metals were within their respective regulatory limits in soil. The BAF for all toxic metals were less than 1 in all sites, indicating minimal bioaccumulation in Lumbricus terrestris. The Ʃ16 PAHs ranged from 7.30 to 77.7 mg kg-1 and 1.10 t...
In this study, the concentration, distribution, ecological and health risk assessment of polychlo... more In this study, the concentration, distribution, ecological and health risk assessment of polychlorinated biphenyls (PCBs) in water and sediment samples from Udu River, Niger Delta Nigeria, was assessed. Water and sediment samples were collected at five different points along the course of the River, which were in proximity to human population. Water samples were liquid-liquid extracted using a mixture of n-hexane and dichloromethane, while sediment samples were soxhlet extracted using acetone/dichloromethane/n-hexane mixture. Extracted PCB congeners were quantified using a gas chromatograph-mass spectrometer. The results revealed that only PCB-167 was detected in water samples, with concentrations ranging from 0.02–1.86 mg L − 1. For sediment samples, the concentration of Ʃ29PCBs ranged from 5.34 to 16.1 ng g − 1. The determined PCB concentrations in both water and sediment samples were within regulatory limits. The concentration of dioxin-like PCBs (dl-PCBs) ranged from 1.07–5.36 n...
Landfills remains an important component in waste management as it deals with municipal solid was... more Landfills remains an important component in waste management as it deals with municipal solid waste directly and complements alternative waste management technologies, which in themselves give rise to residues that require disposal ultimately via landfill. As an assessment study, the work was carried out by visitation to existing dumpsites to obtain needed data and information through the instrumentation of a checklist, interviews, questionnaire and focus group discussions. Stratified random sampling was also used to provide appropriate representation of the societal classes in the population across the 25 Local Government Areas in the State. Results showed that most solid waste collected are deposited in open dumpsites/ landfills on the outskirts of urban areas thereby forming breeding sites for disease vectors and polluting the environment and plausible recommendations for improved waste and environmental management in the State.
The concentrations and potential human health risks through dietary ingestion of PCBs in canned s... more The concentrations and potential human health risks through dietary ingestion of PCBs in canned sardines collected from the Nigerian market were determined. The results shows that the total PCBs concentrations varied from <LOD to 668 ng g−1. The composition of PCBs in the canned sardines followed the order: Penta-PCBs > Hexa-PCBs > Tetra-PCBs > Di-PCB > Deca-PCB > Tri-PCBs > Hepta-PCBs > Octa-PCB. The estimated daily intake for total PCBs ranged from <LOD to 926 ng kg−1 bw day−1 and < LOD to 232 ng kg−1 bw day−1 for child and adult exposures respectively. The TEQs values of the dl-PCBs indicated that these canned sardines are unsafe for consumption. The hazard index and total cancer risk values in 53% of the canned sardines were greater than 1 and 1 × 10−6 respectively indicating that there are adverse non-carcinogenic and carcinogenic risks associated with human consumption of these canned sardines.
Cathode ray tubes are image display units found in computer monitors and televisions. In recent y... more Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelti...
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