Particulate matter concentration levels during intense haze event in an urban environment

This study assessed concentration levels of particulate matter (PM) in the ambient environment of Ilorin metropolis, Nigeria, during haze episodes. Meteorological data (wind speed and direction, rainfall data, sunshine data, relative humidity and temperature) were obtained. Aerocet 531S particle counter (MetOne Instruments, USA) was used to measure four mass concentration ranges of PM (PM_1.0, PM_2.5, PM₁₀ and the total suspended particles (TSP)) in 10 locations taking into consideration land use patterns. Surfer® version 8 (Golden Software LLC, USA) was used to model the spatial variation of particulate matter concentration levels using kriging interpolation griding method. Human exposure assessment was done using the total respiratory deposition dose (TRDD) estimates and statutory limit breach (SLB) approaches. The appearance of dominating weak southern atmospheric wind flow was observed as wind speed ranged from 0 to 6.811 m/s while solar radiation periods ranged from 0.3 to 3.5 h/day. The relative humidity of the metropolis ranged between 28 and 57%, while daily temperature was 15 to 36 °C. Highest concentration levels of PM measured were 73.4, 562.7, 7066.3 and 9907.8 μg/m³ for PM_1.0, PM_2.5, PM₁₀ and TSP, respectively. Very strong negative correlations existed between the PM concentration levels and microclimatic parameters. Spatial variation of the concentration level as modelled using Surfer® version 8 indicated that particulate concentration level increases from south to north. Concentration levels of PM for the 24-h averaging period were generally above the 24-h threshold limit value set by the regulatory agencies for all the locations.     

Flame ionization gas chromatographic determination of phthalate esters in water, surface sediments and fish species in the Ogun river catchments, Ketu, Lagos, Nigeria

The detection and quantification of four phthalate esters??dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP)??in water, sediment, and some fish species were carried out using flame ionization gas chromatography. The samples were collected from the Ogun river catchments, Ketu, Lagos. The DMP was not detected in the water and fish samples but was detected in sediments collected from four of the six sampling sites. The concentration of DEP, DBP, and DEHP in the fish species ranged from 320.0?C810.0, 380.0?C1,080.0, and 40.0?C150.0 ??g/kg in Tilapia sp.; 310.0?C860.0, 400.0?C1,170.0, and 40.0?C110.0 ??g/kg in Chrysichthys sp.; and 320.0?C810.0, 400.0?C3,970.0, and 30.0?C300.0 ??g/kg (DEHP) in Synodontis sp., respectively. The differences in fish phthalate levels are not statistically significant at p?<?0.05, an indication that phthalate esters accumulation is not fish species dependent. The DEP, DBP, and DEHP values recorded are considerably higher than the maximum allowed concentrations for drinking water prescribed by the US Environmental Protection Agency. The phthalate pollution index and biosediment accumulation factor values were also calculated.     

Evaluation of urban solid-waste generation and safety consciousness of waste collectors amidst COVID-19 pandemic

Journal of Material Cycles and Waste Management - This study investigates solid-waste handling practices by municipal waste collectors during COVID-19 pandemic period in Osogbo urban areas with the...     

Determination of total petroleum hydrocarbons and heavy metals in soils within the vicinity of facilities handling refined petroleum products in Lagos metropolis

This article discusses the determination of total petroleum hydrocarbons (TPH) and heavy-metal contamination in soils within areas of refined petroleum products handling in Lagos metropolis. Soil samples were collected randomly from two petrol stations, two auto-mechanic workshops, and a National Electric Power Authority (NEPA) station. Control samples were taken from two low-density residential areas. TPH were estimated gravimetrically following standard methods of TPH analysis, while the heavy metals were determined by atomic absorption spectrophotometry. Sites studied had higher levels of TPH and heavy metals compared to the control samples. For TPH, the petrol stations have mean values of 399.83+/-106.19 and 450.83 +/- 90.58 microg/g, respectively; mechanic workshops, 362.60 +/- 185.84 and 428.55 +/- 119.00 microg/g, respectively; while the NEPA station has 356.20 +/- 210.30 microg/g compared to the control mean of 26.63 +/- 4.58. It revealed that the improper handling of refined petroleum products are potential sources of soil contamination in the sampled sites. This is indicated by the statistically significant levels of TPH and heavy metals observed between the control samples and those collected from the petroleum products handling sites. Bioremediation using microorganisms and plants is recommended.     

Soil properties in the metropolitan region of Ibadan, Nigeria: implications for the management of the urban environment of developing countries

This paper examines the variation in the properties of surface soils from the rural, through sub-urban, to the urban zones of Ibadan metropolitan area, south-west Nigeria. Soils were sampled at 0–20 cm depth in the northern part of the metropolis. Statistical techniques were used to compare the data obtained in the three zones. The results of the analyses clearly show that the mean values of nine out of the eighteen soil properties analysed differed significantly between the three zones. In particular, the concentration of two of the three heavy metals analysed in the study, that is, zinc and lead were higher in the urban zone than in the other two zones. The accumulation of heavy metals in the soils of the urban environment of developing countries requires urgent attention from environmentalists and urban development planners. It is important to prevent such heavy metals leaching into the underground water supply, and, to minimise the health risks to both humans and animals that depend solely on this source of water supply.     

Farming in the urban environment of a developing nation — a case study from Ibadan metropolis in Nigeria

Summary The major characteristics, problems and prospects of farming in an urban environment of a developing nation are investigated using the Ibadan metropolitan area of Nigeria as a case study. Eight hundred farmers, made up of both part-time and full-time farmers were interviewed in five urban fringe settlements in the study area. Findings revealed that farming in the urban environment is guided by the logic of survival since most of the farmers engaged in urban cultivation are mainly low-income earners and they farm mainly to reduce their expenses on food and to supplement the family's income. The major problem confronting farming in the area is competition from non-agricultural land uses. Nevertheless, more than half (50.5 percent) of the farmers, who had been approached to sell their farmlands for non-agricultural uses in the area, rejected the offer, indicating that the prospects of continued farming are thought to be good. Measures like the sale of urban land at its agricultural value, provided the land remains in cultivation, as well as the further provision of land in and around the farmers' working places, could improve their access to land for extended farming.Dr Adeniyi Gbadegesin is a lecturer in the Department of Geography at the University of Ibadan. He has published papers widely on agricultural topics.     

Bioremediation of cutting fluids contaminated soil by Pleurotus tuber-regium Singer

This study investigated the effect of inoculation of Pleurotus tuber-regium, a Nigerian white rot fungus, period of incubation, different levels of contamination on cutting fluids degradation in contaminated soil over 30, 60, and 90 days. Control for different levels of cutting fluids was also used to compare rates of bioremediation of the contaminant in the soil. At the end of each incubation period, the mycelia-ramified substrate was separated from the soil layer and dried. The soil samples were analyzed for physico-chemical parameters; total petroleum hydrocarbon, lignin content by determining the acid detergent fraction (ADF), heavy metals content of the soil using flame atomic absorption spectrophotometer, and changes in the polyphenol oxidase and peroxidase activities were also determined after 1, 2, and 3 months. P. tuber-regium improved the nutrient status of the soil and increased enzyme activity was recorded. A reduction in the pH and heavy metal contents of the soil at all levels of cutting fluids concentrations was detected. The lignin in the rice straw decreased from 34.50% in the control to 8.06% at 30% cutting fluids concentration after 3 months of incubation. The highest TPH loss of 30.84% was recorded at 20% cutting fluids contamination after 3 months compared to 13.75% at the onset of the experiment. The improvement of the nutrient contents of the soil, bioaccumulation of heavy metals, degradation of TPH, lignin, and increased activity of polyphenol oxidase and peroxidase was due to biodegradation of the cutting fluids.     

Effects of land clearing methods on the properties and productivity of an Alfisol in south-western Nigeria

Summary This study investigated the impact of manual and mechanical land clearing methods on the soils and the yield of maize in a part of the rainforest belt of south-western Nigeria. The results of the study revealed that the mean values of such soil properties as the organic matter, bulk-density, total porosity, soil moisture and to some extent the exchangeable actions in the mechanically cleared farms differed significantly at (P 0.05) from those in the manually cleared farms and the rainforest vegetation used in the control plot. There was no significant difference in the average yield of maize for the three years for which records were available.Dr Adeniyi Gbadegesin is a Senior Lecturer in the Department of Geography, University of Ibadan, where Miss B. B. Olusesi was a recent graduate.     

Assessment of the exposure of two fish species to metals pollution in the Ogun river catchments, Ketu, Lagos, Nigeria

The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria’s river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.