Concentration of Heavy Metals in the Soils near Some Mechanic Villages in Abeokuta Metropolis, Ogun State, Nigeria.

Soils and water bodies near auto mechanic village (MV) contain heavy metals, which pollute the environments and are hazardous to human and environmental health. Assessment of heavy metal concentration in three replicate soil and water samples from three MVs (Fajol, Id-Aba and Kotopo) in Abeokuta metropolis in Nigeria was conducted. Heavy metal concentrations in topsoil of the MVs showed copper ranging from 0.02 mgkg-1 in the topsoil at Idi-Aba MV to 126.89 mgkg-1 for topsoil at Kotopo MV. The level of copper detected in Kotopo MV soil is however higher than the allowable limits for Sweden, Netherlands and Germany. Mean concentration of zinc in soils of the MVs were 2.89, 0.91 and 86.23 mgkg-1 respectively for Fajol, Idi-Aba and Kotopo MV respectively. Metal enrichment factor indicated that the contamination degree ranged from unpolluted to moderately polluted areas. Copper is the most enriched metal in the soil of the MVs especially at Kotopo MV. Relative abundance of the metals in the topsoil (0-15cm) in Fajol MV follow the order Zn > Ni> Cr >Pb >Cu > Co> Cd.  For the Idi-Aba MV, relative abundance is in the order Ni > Zn > Cr > Pb> Cu > Co and Cd, and that of Kotopo MV was Cu >Zn> Pb > Ni > Cr, Co and Cd. Mean heavy metal in the water samples were lower than those found in the soils of the MVs. Stream water near the Kotopo MV had the highest concentration of most metals. Zinc had the highest mean concentration of 2.02 mgL-1 while copper was 1.09 mgL-1.  There is an urgent need to put measures in place to monitor the activities in these MVs in order to safeguard peoples’ health environmental integrity

URBAN FLOOD IMPACTS, FLOOD WATER QUALITY AND RISK MAPPING OF OLODO AREA, IBADAN, NIGERIA

This study assessed urban flood impact, flood water quality and vulnerability around Olodo area of Ibadan region, Nigeria. The study employed remote sensing and GIS techniques in creating vulnerability and risk maps. Digital terrain model (DTM) was used to get the topography of the study area. Footprints of buildings along the Egberi riverbank and flood plain in Olodo were created in the GIS environment from high resolution satellite imagery. Buffering operation was conducted to classify the buildings into risk zones based on closeness to the riverbank using ArcGIS 10.0. The study revealed that 326 buildings were within the very vulnerable and vulnerable zones because they were less than 15.2m away from the riverbank. The characteristics of water quality change during the flood and non-flood periods. TSS, DO, NOD, and COD were all higher during the flood event. Microbial analysis showed that water quality levels in the floodwater exceeded water quality standards (e.g., the coliform excess from 10 to 10,000 times), and thus this may be a health risk for local people during flood events. Concentration of Escherichia coli (E. coli) ranged from 484 to 1290 cfu/100 mL during flooding compared to 192 to 295 cfu/100 mL after flood. Salmonella was found to be high ranging from 659 to 1840 cfu/100 mL during flooding compared to 530 to 1034 cfu/100 mL after flooding.     &nbsp

SPATIAL DISTRIBUTION AND HEALTH RISK ASSESSMENT OF HEAVY METALS IN URBAN PARKS AND GARDENS SOILS IN LAGOS STATE, NIGERIA

Distribution and health risk assessment of heavy metals in urban parks and gardens Gani Fawehinmi Park, Ojota, (GFP), Oshodi Heritage Park Oshodi (OHP), Ikorodu/Ipado Garden (IIG), MKO Abiola Gardens, Ojota (MKO), and MOE Garden, Alausa (MOE) soils in Lagos Metropolis, Nigeria were examined using Index of Geo-accumulation (Igeo), Potential Ecological Risk Index (RI) and health risk model. Urban parks and gardens soils were substantially polluted by Cu and Pb due closeness to highways where heavy metals emitted from motor vehicles are deposited.  Geoaccumulation index (Igeo) values for Pb were 10.616, 10.060, 9.027, 8.862 and 8.665 for GFP, OHP, IIG, MKO and MOE respectively. RI values for all the sites showed high pollution as they were all above 200. Health risk assessment revealed that children who visit the urban parks and garden in Lagos State are more exposed to cancer risk from Pb especially through ingestion. Results from this study provided valuable information on the pollution levels of urban parks in Lagos, Nigeria as a result of traffic related emissions and calls for proper monitoring of anthropogenic activities in the metropolis and reduce the human health impacts. The planting of hedge plants and erection of low walls could serve as shield against traffic pollution for the roadside parks     &nbsp

Physicochemical and microbiological examination of hand-dug wells, boreholes and public water sources in selected areas of Ibadan, Nigeria

This study examined some physicochemical and microbiological characteristics of some water sources and evaluates their health implications in selected areas of Ibadan, Nigeria. Forty (40) water samples were collected into 1-litre plastic kegs from hand-dug wells, boreholes and public water points between June 12 and July 11, 2014. Samples were analysed for physical, chemical and microbial parameters using standard procedures. Well-structured questionnaires were used to elicit information on sanitation conditions in the areas. Electrical conductivity in many of the sampled water were higher than the recommended limit, while TDS were within the desirable limit of 200 mg/l except for the borehole at Ita-Baale Borehole (IB) and hand dug well at Oke-Aare (OAH). Microbial assessment of water samples in most areas confirmed the presence of vibrio species due to faecal pollution. Bacterial isolates identified in some of the water samples were Enterobacter cloaca, Escherichia coli, Klebsiella oxytoca, Pseudomaonas fluorescens and Salmonella spp. The study revealed that sanitary facilities including toilets and improved latrines are lacking in many areas. Hand dug wells had the highest frequency of occurrence pollutants and bacteria due to their close proximity to pit latrines. The study concluded that residents in the study area are exposed to polluted water sources, which pose serious threat their health. This study added to the existing data on the inadequacy of sanitation in urban centres in the country hence the need for increased effort in the provision of more cleaner and well protected water sources such boreholes and piped-borne water.Keywords: Hygiene, microbial contamination, sanitation, urban slums, water quality, healt

Assessment of Groundwater Contamination by Textile Effluent Discharges in Ikorodu, Nigeria

This paper assessed physicochemical properties (temperature, pH, acidity, alkalinity, colour, odour, taste, EC, TDS, TH, turbidity, bicarbonate, phosphate, nitrate, Ca2+, Mg2+, Na+, K+, Cl- & SO42- as well as heavy metal concentrations heavy metals (Cd, Cr, Cu, Fe, Pb and Zn) of selected wells and borehole near textile industries in Ikorodu, Nigeria. The physicochemical parameters were analysed using standard methods by APHA, while heavy metals were analysed using atomic absorption spectrometer (AAS). The pH of water from the boreholes and hand-dug wells ranged from 5.90 to 6.70. The well water had higher total hardness, calcium, magnesium, sulphate and chloride compared to the boreholes. Alkalinity in the boreholes ranged from 740.2 to 820.4 mg L-1 compared to wells that ranged from 144.4 to 670.2 mg L-1. EC for the boreholes ranged from 124.5-182.3 μS cm-1 compared to EC of wells that ranged from 216.2-385.6 μS cm-1. TDS ranged from 48.6-60.3 mg L-1 in the borehole compared to 62.5-120 mg L-1 in the wells. Concentration of Fe ranged from 0.12 to 1.2 mg L-1 in the boreholes compared to 1.2 to 1.60 mg L-1 found in the well water. Zn, Pb, and Cu ranged from 0.60 to 1.20 mg L-1, 0.02 to 0.03 mg L-1 and 0.04 to 0.06 mg L-1 respectively. Concentrations of Fe and Pb were above the permissible limits of WHO and NIS. A possible source of pollution is seepage of effluent discharge through the porous soil into the groundwater and this poses great danger to the health of the people who consume the water

Assessment of Traffic Related Heavy Metals Pollution of Roadside Soils in Emerging Urban Centres in Ijebu-North Area of Ogun State, Nigeria

This study investigated the concentration of eight critical heavy metals in the roadside soils of selected urban centres in Ijebu-North Local Government Area of Ogun State, SW, Nigeria. Thirty-six composite soil samples were collected along the roadside based on distances to the roads. Physiochemical properties and concentrations of heavy metals (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) in roadside soils in some selected locations were determined using atomic absorption spectroscopy. Accumulation of heavy metals in top soils is greately influenced by traffic volume and all the heavy metals exhibited a significant reduction in the roadside soils with increasing distance from the road. Metal concentrations in the roadside soils followed order of Zn>Pb>Fe>Cu>Mn>Cd>Cr. Concentration of Zn was 156.09 mg/Kg in roadside soils of Ijebu-Igbo/Oru/Ago-Iwoye which is experiencing high volume of traffic , while it ranged from 10 \u2013 47 mg/Kg for Ijebu-Igbo/Bajowa/Akanran road with low traffic volume. Pb concentration of 26.7 mg/Kg was observed in : Ijebu-Igbo/Oru/Ago-Iwoye road especially in centre of the city. Concentration of all heavy metals examined were below the EU guideline, however, the paper suggested a regular monitoring and assessment to ensure sustainable management of the urban environment and reduction of traffic-related contamination of soil, plants and water

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) on Selected Dumpsites in Abeokuta Metropolis, SW, Nigeria

Knowledge of the concentration of polycyclic aromatic hydrocarbon (PAHs) in urban soils remains insufficient in developing countries like Nigeria despite their toxic effects and suspected human carcinogens, mutagens and endocrine disruption. This study aimed to determine the concentration of PAHs in soil of three dumpsites in Abeokuta metropolis, Ogun State, Nigeria. Concentrations of individual PAHs were determined using Gas Chromatography Flame Ionization Detector (GC-FID). The total PAHs concentrations at 0-15 cm depth were 29.0 mg kg-1, 41.6 mg kg-1 and 11.9 mg kg-1 for Igbore, Saje and Alogi dumpsites respectively while the corresponding total PAHs concentrations at 15-30 cm depth were 9.3 mg kg-1, 28.3 mg kg-1 and 11.0 mg kg-1 respectively. These concentrations were slightly lower than the Dutch guideline limits of 40 mg kg-1 except for that of Saje at 0-15 cm depth. The amounts of fluoranthene at Igbore dumpsite in the two depths were 23.64 mg kg-1 and 8.02 mg kg-1, with a total sum of 10 PAHs compounds of 19.12 mg kg-1. The results showed that the highest concentration of a single PAHs compound was at Saje dump-site with fluoranthene value of 33.75 mg kg-1 and 22.74 mg kg-1 at the depths of 0-15 and 15-30 cm respectively. Isomer ratio for fluoranthene/pyrene was 2.69 at Alogi dumpsite, which suggested that the PAHs were from pyrogenic sources. Carcinogenic PAHs constituted about 1.29-15.69 % of the total PAHs detected in the dumpsite raising concerns of human exposure through the food chain

Urban agriculture: a global analysis of the space constraint to meet urban vegetable demand

Urban agriculture (UA) has been drawing a lot of attention recently for several reasons: the majority of the world population has shifted from living in rural to urban areas; the environmental impact of agriculture is a matter of rising concern; and food insecurity, especially the accessibility of food, remains a major challenge. UA has often been proposed as a solution to some of these issues, for example by producing food in places where population density is highest, reducing transportation costs, connecting people directly to food systems and using urban areas efficiently. However, to date no study has examined how much food could actually be produced in urban areas at the global scale. Here we use a simple approach, based on different global-scale datasets, to assess to what extent UA is constrained by the existing amount of urban space. Our results suggest that UA would require roughly one third of the total global urban area to meet the global vegetable consumption of urban dwellers. This estimate does not consider how much urban area may actually be suitable and available for UA, which likely varies substantially around the world and according to the type of UA performed. Further, this global average value masks variations of more than two orders of magnitude among individual countries. The variations in the space required across countries derive mostly from variations in urban population density, and much less from variations in yields or per capita consumption. Overall, the space required is regrettably the highest where UA is most needed, i.e., in more food insecure countries. We also show that smaller urban clusters (i.e., <100 km2 each) together represent about two thirds of the global urban extent; thus UA discourse and policies should not focus on large cities exclusively, but should also target smaller urban areas that offer the greatest potential in terms of physical space

Exploring the theories, determinants and policy-options of street vending: a demand-side approach

Street vending has been a common feature of urban centres for several decades, with a relatively high proportion of developing countries’ populations depending on it for employment, income or survival. Taking a supply-side approach, studies have shown that urban planners’ responses to street vending have followed the modernism theory. In this paper, we take a demand-side (buyer-focused) approach to studying street vending, which to date has received little attention from the academic community. Employing data from Lagos state, Nigeria, we report four explanations underpinning the demand-side of street vending: formal economy failures, social/redistributive, financial gains, and multifeature. These are, in turn, explained by individuals’ marital status, level of education, and perception. Our findings highlight the need for urban planners to embrace pragmatic policies in addressing these demand-side drivers of street vending and use of urban space, rather than criminalising its actors

Wastage amidst shortage: Strategies for the mitigation of standby electricity in residential sector in Nigeria

Abstract : Due to rising population and the increasing rate of urbanization, residential electricity usage accounts for a large chunk of Nigeria’s electricity consumption. However, little attention is paid to electricity conservation in the country. In response to this, several studies are been tailored to ensure a rapid reduction in energy consumption through various alternatives including energy efficient technologies given the current state of inadequate electricity supply in the country. On this note, this article discusses the significance of standby electricity in Nigeria. The electricity generation and consumption patterns were briefly discussed while the current electricity saving behaviour and practices among the urban dwellers were detailed with a case study analysed. Based on the case study, it was discovered that the mean standby load across the 30 households were estimated at 60 W ranging from 34-144 W. Also, standby consumption accounts for 13-44% of the annual electricity consumption across the households. Finally, the strategies for electricity saving and sustainable consumption, most especially the mitigation of standby electricity were highlighted