I.M. Adekunle, O. Olorundare and C. Nwange
The aim of this paper is to assess the safety of commonly consumed green leafy vegetables in southwest Nigeria in relation to lead (Pb) contamination.
Abstract
Purpose
The aim of this paper is to assess the safety of commonly consumed green leafy vegetables in southwest Nigeria in relation to lead (Pb) contamination.
Design/methodology/approach
In total, 585 samples of five species of commonly consumed green leafy vegetable samples were procured from 15 outdoor markets and selected farms in three major cities (Abeokuta, Ibadan and Lagos) in the region. Samples were fragmented to two portions (water‐washed and unwashed) and subjected to acid digestion. The Pb in the digests was measured using a flame atomic spectrophotometer. Relevant information was elicited from traders by the administration of a structured questionnaire. Acceptable daily intakes of the metal from the vegetables were estimated using the FAO/WHO total diet study.
Findings
Lead concentrations in all the vegetable samples (6.35‐20.85 mg/kg) exceeded the recommended value of 0.3 mg/kg for green leafy vegetables. The estimated daily intakes of the metal (1.11×10−2 to 2.02×10−2 mg/kg bw) were also higher than the FAO/WHO safety threshold of 3.0×10−3 to 4.0×10−3 mg/kg bw for Pb. Washing the vegetables with water reduced Pb concentrations and EDIs by 11.36 to 43.52 per cent but did not bring the values below the recommended limit.
Research limitations/implications
It was impossible to evaluate the effect of distance from highways on metal concentration because traders were not restricted to a particular location in the outdoor markets in the country.
Originality/value
The study constitutes an evaluative probe into the degree of exposure of commonly consumed vegetables to Pb contamination, contributing to the database of knowledge on toxic metal daily intake from Nigerian foods and environmental contamination.
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Nicholas Adesina Ojo-Awo, Hafeez Idowu Agbabiaka and Abiola O. Ilesanmi
The purpose of this paper is to investigate the physico-chemical properties of the groundwater surrounding the Solous (solid waste dumpsite) at Isheri, Lagos, Nigeria.
Abstract
Purpose
The purpose of this paper is to investigate the physico-chemical properties of the groundwater surrounding the Solous (solid waste dumpsite) at Isheri, Lagos, Nigeria.
Design/methodology/approach
In total, 40 groundwater samples were collected from ten pre-determined sampling stations. Three sample stations were established before the dumpsite; three sample stations were located in the vicinity of the dumpsite in the direction of the leachate plume, while the remaining four sample stations were situated further away and acted as a control. Sampling was carried out four times during the study period (twice each in the rainy and dry seasons). The parameters measured in situ were air and water temperatures (using mercury-in-glass bulb thermometer) and pH (using pH meter). Calcium and magnesium contents were measured using the Ca-Mg indicator; sodium content was measured using the flame emission spectrophotometry and phosphate was measured using the flame photometry. The selected heavy metals (copper, iron, lead, cadmium, zinc and manganese) were measured by using the atomic absorption spectrometer. The oxygen parameters, such as dissolved oxygen, biological oxygen demand, chemical oxygen demand and organic matter, were determined titrimetrically. The data obtained were subjected to descriptive statistics and analysis of variance (ANOVA).
Findings
The results showed that many parameters had higher values in the dry season than in the rainy season. Temperature (27.75±0.95°C), alkalinity (211.37±82.78 mg/LCaCO3), phosphate (0.30±0.07 mg/L) and sulfate (2.78±0.35 mg/L), sodium ion (41.95±18.86 mg/L), dissolved oxygen (2.98±0.57 mg/L) and COD (33.54±4.50 mg/L) had higher mean values in the dry season than in the rainy season. On the other hand, the mean values of electrical conductivity (1,224.85±370.63), nitrate (0.01±0.003 mg/L), chloride (98.76±21.58 mg/L), calcium ion (5.38±0.68 mg/L), magnesium ion (3.05±0.05 mg/L), BOD (22.37±2.20 mg/L) and pH (6.31±0.18) were higher in the rainy season than in the dry season. The heavy metals (iron 1.10±0.05 mg/L, lead 0.12±0.07 mg/L, manganese 0.01±0.004 mg/L, copper 0.15±0.003 mg/L, zinc 0.07±0.004 mg/L and cadmium 0.02±0.02 mg/L) were fairly uniform all year round. There was also a marked decline in the values as one moved away from the dumpsite.
Practical implications
The implication of the findings is that human health is remarkably dependent upon safe and clean drinking water. Preserving the water resources and hindering them from pollution is preferred to the treatment of polluted water and rendering it suitable for consumption. The high electrical conductivity values obtained in the groundwater samples near the dumpsites are an indication of the effect of leachate on the groundwater quality. The high concentrations of dissolved solids in the groundwater may decrease the palatability and may cause gastro-intestinal irritation in humans, and laxative effect particularly on transits.
Originality/value
The pollutants from the various waste components disposed at the dumpsite percolate into the ground to pollute the groundwater. The groundwater is transported in the line of flow away from the vicinity of the dumpsite to pollute the groundwater in the area. The extent of contamination level of groundwater quality due to leachate percolation depends upon a number of factors like chemical composition of leachate, rainfall, depth and distance of the well from the dumpsite. Groundwater samples of different depths and distances from dumpsites were analyzed in the present study to understand the level of a combination.
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The purpose of this paper is to examine the Summer performance, comfort, and heat stress in structural timber buildings. The research utilises building simulation as a tool to…
Abstract
Purpose
The purpose of this paper is to examine the Summer performance, comfort, and heat stress in structural timber buildings. The research utilises building simulation as a tool to investigate the performance of the case study buildings under non-extreme weather conditions.
Design/methodology/approach
The research explores three UK sites using the test reference year (TRY) weather files for the current and future weather conditions. The study focuses on the Summer performance and heat stress in non-extreme weather conditions; therefore, the Design Summer Year (DSY) weather files are not used for the simulations. The simulation data are calibrated and validated using the measured data from the field study.
Findings
The results revealed the mean predicted temperatures varied from 20.2–20.8°C for the 2000s. The mean temperatures for the 2030s ranged from 23.1 to 24.2°C. Higher temperatures are predicted at the buildings in the Southeast site than the Midlands and the Northwest sites. The results revealed that there is no significant improvement in the thermal environment when the floor area and the floor-to-ceiling height are increased. However, the study showed that the integration of different design interventions can improve the future performance and resilience of the buildings in various weather conditions.
Research limitations/implications
By applying the wet-bulb globe temperature (WBGT) and the Universal Thermal Comfort Index (UTCI) mathematical models to calculate the heat stress at the buildings, the study proposes the WBGT of 20.0°C and the UTCI of 24.1°C as possible heat stress indicators for occupants of the buildings in the 2030s.
Practical implications
On the one hand, the results revealed the maximum temperatures in some of the case study buildings exceed the comfort threshold (28°C). On the other hand, the study showed that occupants of the buildings are not prone to extreme Summertime overheating and heat stress under moderate weather conditions. However, different outcomes may be predicted if DSY weather files for the selected sites are considered.
Originality/value
This study is the first reported work to explore building simulation and mathematical equations to investigate Summer performance, comfort and heat stress indexes in timber buildings under moderate weather conditions in different regional sites in the UK.
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The purpose of this paper is to examine the seasonal performance, occupants’ comfort and cold stress in cross-laminated timber school buildings located in the USA (Northeast…
Abstract
Purpose
The purpose of this paper is to examine the seasonal performance, occupants’ comfort and cold stress in cross-laminated timber school buildings located in the USA (Northeast region).
Design/methodology/approach
The Fall survey was done from October–November 2017. In the Winter, it was considered from December 2017–February 2018. The study measured environmental parameters in the chosen spaces. The research applied the wet-bulb globe temperature (WBGT) model to determine the indexes in various seasons.
Findings
In the Fall, the average inside temperature was 21.2°C, the average RH was 50.7 per cent, and the mean dew-point was 9.3°C. The mean inside temperature was 20.5°C in the Winter while the mean RH was 23.9 per cent and the average dew-point was −1.9°C. The overall mean inside temperatures in both seasons were within the ASHRAE comfort temperature limits for cold seasons. During the surveys, higher average values of temperature, RH and dew-point were measured in the offices than the other spaces.
Practical implications
The research showed people might be subject to lower temperatures in the hall than the other spaces. Some design parameters and occupation hours may contribute to the lower temperatures reported in the hall than the different spaces.
Originality/value
The study proposes the WBGT of 16.0°C and 13.7°C as the stress indexes in the Fall and Winter seasons correspondingly. Last, the research suggests a WBGT of 14.9°C as the overall mean stress index within the spaces considered in this study.
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Ibrahim Ayoade Adekunle, Olukayode Maku, Tolulope Williams, Judith Gbagidi and Emmanuel O. Ajike
With heterogeneous findings dominating the growth and natural resources relations, there is a need to explain the variances in Africa's growth process as induced by robust…
Abstract
Purpose
With heterogeneous findings dominating the growth and natural resources relations, there is a need to explain the variances in Africa's growth process as induced by robust measures of factor endowments. This study used a comprehensive set of data from the updated database of the World Bank to capture the heterogeneous dimensions of natural resource endowments on growth with a particular focus on establishing complementary evidence on the resource curse hypothesis in energy and environmental economics literature in Africa. These comprehensive data on oil rent, coal rent and forest rent could provide new and insightful evidence on obscure relations on the subject matter.
Design/methodology/approach
This paper considers the panel vector error correction model (PVECM) procedure to explain changes in economic growth outcomes as induced by oil rent, coal rent and forest rent. The consideration of the PVECM was premised on the panel unit root process that returns series that were cointegrated at the first-order differentials.
Findings
The paper found positive relations between oil rent, coal rent and economic development in Africa. Forest rent, on the other hand, is inversely related to economic growth in Africa. Trade and human capital are positively related to economic growth in Africa, while population growth is negatively associated with economic growth in Africa.
Research limitations/implications
Short-run policies should be tailored towards the stability of fiscal expenditure such that the objective of fiscal policy, which is to maintain the condition of full employment and economic stability and stabilise the rate of growth, can be optimised and sustained. By this, the resource curse will be averted and productive capacity will increase, leading to sustainable growth and development in Africa, where conditions for growth and development remain inadequately met.
Originality/value
The originality of this paper can be viewed from the strength of its arguments and methods adopted to address the questions raised in this paper. This study further illuminated age-long obscure relations in the literature of natural resource endowment and economic growth by taking a disaggregated approach to the component-by-component analysis of natural resources factors (the oil rent, coal rent and forest rent) and their corresponding influence on economic growth in Africa. This pattern remains underexplored mainly in previous literature on the subject. Many African countries are blessed with an abundance of these different natural resources in varying proportions. The misuse and mismanagement of these resources along various dimensions have been the core of the inclination towards the resource curse hypothesis in Africa. Knowing how growth conditions respond to changes in the depth of forest resources, oil resources and coal resources could be useful pointers in Africa's overall energy use and management. This study contributed to the literature on natural resource-induced growth dynamics by offering a generalisable conclusion as to why natural resource-abundance economies are prone to poor economic performance. This study further asks if mineral deposits are a source or reflection of ill growth and underdevelopment in African countries.
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Adekunle Sulaimon Ogunbadejo, Sunday Aribo, Oluwatoyin Adenike Olaseinde, Oladeji O. Ige and Peter Olubambi
This paper aims to investigate the stability of passive oxide film formed on the surface of 316L stainless steel in 3.5 Wt.% NaCl in the presence of two environmentally non-toxic…
Abstract
Purpose
This paper aims to investigate the stability of passive oxide film formed on the surface of 316L stainless steel in 3.5 Wt.% NaCl in the presence of two environmentally non-toxic inhibitors, i.e. leaf extracts of Musa spp. (MS) and Jatropha curcas (JC).
Design/methodology/approach
Current transients and potentiodynamic polarization curves were used to explain the stability of the passive film on Current transients and potentiodynamic polarization curves were used to explain the stability of the passive film on 316L stainless steel at both ambient temperature (25 °C) and 70 °C. For the potentiostatic tests, the coupons underwent cathodic stripping to remove the native oxide on their surfaces at −850 mV for 600 s, and a potential of 50 mV was imposed to observe the repassivation for 200 s. For the potentiodynamic tests, the pitting potential measured at 100 μA/cm2, corrosion potential and cathodic current density were obtained for analysis.
Findings
The current transients perfectly fitted into the exponential decay curve; i = is + ipeak exp(−t/τ), where the decay constant, τ measures the repassivating speed and extent to which the newly formed film heals and stabilizes. The current transients showed that MS and JC help in the repassivating process, especially at 300 ppm and 200 ppm, respectively, both at the lower temperature. The potentiodynamic curves mostly correlated with the current transients except for the hybrid inhibitor. The inhibitors increased the pitting potentials at concentrations that are correlated to their scanning electron micrograph images.
Research limitations/implications
Because they are cheap and environmentally friendly, plant extracts that are proven corrosion inhibitors could be used to aid the formation of passive film on passive alloys in not-so-aggressive environments.
Practical implications
Both MS and JC improve the film stability mostly at intermediate concentrations of 200 and 300 ppm, respectively, at ambient temperature and 70° C.
Social implications
Using leaf extracts of plants as green inhibitors is considered an environmentally friendly engineering solution.
Originality/value
The leaf extracts are a convenient resource of green inhibitors because their plants are readily available or could be easily naturalized, the processing technique to obtain the extracts is very cheap and the inhibitors are environmentally friendly. In addition, cathodic stripping exposes a relatively larger surface area than that obtained using the most common forms of depassivation; hence, the efficiency of the inhibitor in aiding the formation of the new oxide film to cover the bare surface would be better measured. There is very lean research data on the combined use of green inhibitors and cathodic stripping to study repassivating kinetics of passive alloys.
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Adekunle Oke, Jasmina Ladas and Moira Bailey
This study aims to explore the motivation as well as barriers for ethical food consumption behaviour by focussing on the food consumption pattern of young adults in the North East…
Abstract
Purpose
This study aims to explore the motivation as well as barriers for ethical food consumption behaviour by focussing on the food consumption pattern of young adults in the North East of Scotland. Considering the recent involvement of young adults in environmental activism, consumption behaviour of young adults in the North East of Scotland, an oil-based community, presents essential research interest to understand whether young adults often contemplate the consequences of their lifestyle.
Design/methodology/approach
The authors explored the perceptions of ten purposive recruited young adults using semi-structured interviews to understand factors underpinning consumer's decision-making towards ethical food products.
Findings
The study reveals three key factors influencing ethical food consumption behaviour among young adults. The findings show that personal health and well-being are the main reasons why consumers engage in ethical food consumption. Also, it is observed that information facilitates decision-making by raising awareness regarding the social, environmental and health consequences of food production and consumption. Further, the findings show that situational attributes, such as product price and product availability, are creating dissonance when engaging in ethical food consumption.
Originality/value
This study contributes to sustainability research and the ongoing debate on consumerism by exploring ethical food consumption behaviour and highlights the need to address situational challenges, such as product price and availability. The study suggests that interventions to address current consumption patterns should also emphasise the social and personal benefits of food consumption rather than the environmental benefits that have been the focus of prior research.
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Noah Olasehinde, Uche Abamba Osakede and Abdulfatai Adekunle Adedeji
This study investigates the effect of user fees on access and waiting time in Nigeria. For access, the effect of user fees on both preventive and curative care; and the effect of…
Abstract
Purpose
This study investigates the effect of user fees on access and waiting time in Nigeria. For access, the effect of user fees on both preventive and curative care; and the effect of user fees on waiting time at public healthcare facilities were examined. User fees are vital for the fiscal sustainability of healthcare provision for most African economies. Its imposition could debar healthcare access by the poor while its removal can reduce quality of care and induce longer waiting time.
Design/methodology/approach
The wave 3 of the Nigerian General Household Survey (2015/16) data was used for users of public health facilities. Access to healthcare was modelled using utilization data in a logistic regression model while waiting time was through the Negative Binomial Regression Model (NBRM).
Findings
The analyses showed significant effects of user fees on access to both preventive and curative care and on time spent waiting to make use of healthcare services. Individuals were able to access healthcare services regardless of amounts paid. Also, there was a non-negative effect of user fee imposition on waiting time.
Practical implications
Nigeria should improve healthcare facilities to address the enormous demand for healthcare services when designing policy for health sector.
Originality/value
This paper shows that even with the imposition of user fees, healthcare facilities could still not cater for the rising healthcare needs of the populace but cautioned that its abolition may not be a preferred option.
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Dupe Temilade Otolowo, Abiodun Adekunle Olapade, Samouel Olugbenga Oladele and Felix Egbuna
Fresh catfish (Clarias gariepinus) is highly perishable. This paper aims to investigate the drying characteristics and quality of body-mass dehydrated catfish to determine the…
Abstract
Purpose
Fresh catfish (Clarias gariepinus) is highly perishable. This paper aims to investigate the drying characteristics and quality of body-mass dehydrated catfish to determine the effective dehydration parameters for preservation.
Design/methodology/approach
Brine concentration (3-9 per cent), brining time (30-90 min) and drying temperature (90-130°C) interacted using the response surface methodology. Preliminary experiments were conducted to select treatments. Moisture content and ratio and drying rate were determined and fitted into five thin-layer drying models; the goodness of fit was evaluated by average grade ranking of the regression parameters. Proximate compositions and microbial load of dehydrated catfish were determined using standard methods.
Findings
Treatments with 110°C gave initial higher drying rate (0.034-0.043 kg H2O/kg solid/h) and shorter drying time (20-21 h). Drying occurred at two falling rate periods. Midilli model ranked first in fitting the drying data. It explained up to 99.6-99.7 per cent of the total variations in the independent variables with low values of error terms; RMSE was 0.02131-0.01794 and χ2 was 0.00037-0.00043, indicating good predictive quality. Processing parameters positively and significantly (p < 0.05) influenced the proximate compositions of dehydrated catfish. Treatment: 6 per cent brine, 90 min and 110°C presented the most effective dehydration parameters for quality preservation of body-mass catfish.
Practical implications
The dehydration technique used in this study could enhance nutritive quality and storage stability of body-mass dehydrated catfish that could serve as a useful and convenient tool for commercial application.
Social implications
Hygienically processed dehydrated catfish of good quality could be used as a source of nutrients to ameliorate malnutrition and reduce post-harvest losses of catfish.
Originality/value
The effective processing parameters established is an important step to harness the high nutrients and economic values embedded in catfish.
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Chinedu Chinakwe, Adekunle Adelaja, Michael Akinseloyin and Olabode Thomas Olakoyejo
Inclination angle has been reported to have an enhancing effect on the thermal-hydraulic characteristics and entropy of some thermal systems. Therefore, this paper aims to…
Abstract
Purpose
Inclination angle has been reported to have an enhancing effect on the thermal-hydraulic characteristics and entropy of some thermal systems. Therefore, this paper aims to numerically investigate the effects of inclination angle, volume concentration and Reynolds number on the thermal and hydraulic characteristics and entropy generation rates of water-based Al2O3 nanofluids through a smooth circular aluminum pipe in a turbulent flow.
Design/methodology/approach
A constant heat flux of 2,000 Watts is applied to the circular surface of the tube. Reynolds number is varied between 4,000 and 20,000 for different volume concentrations of alumina nanoparticles of 0.5%, 1.0% and 2.0% for tube inclination angles of ±90o, ±60o, ±45o, ±30o and 0o, respectively. The simulation is performed in an ANSYS Fluent environment using the realizable kinetic energy–epsilon turbulent model.
Findings
Results show that +45o tube orientation possesses the largest thermal deviations of 0.006% for 0.5% and 1.0% vol. concentrations for Reynolds numbers 4,000 and 12,000. −45o gives a maximum pressure deviation of −0.06% for the same condition. The heat transfer coefficient and pressure drop give maximum deviations of −0.35% and −0.39%, respectively, for 2.0% vol. concentration for Reynolds number of 20,000 and angle ±90o. A 95%–99.8% and 95%–98% increase in the heat transfer and total entropy generation rates, respectively, is observed for 2.0% volume concentration as tube orientation changes from the horizontal position upward or downward.
Originality/value
Research investigating the effect of inclination angle on thermal-hydraulic performance and entropy generation rates in-tube turbulent flow of nanofluid is very scarce in the literature.