Determination of the Contamination of Groundwater Sources in Okrika Mainland with Polynuclear Aromatic Hydrocarbons (PAHs)

In this study, we examined the presence and concentrations of six polynuclear aromatic hydrocarbons (PAHs) in groundwater sources of Okrika mainland impacted by effluent discharges from a petroleum refinery into her surrounding Creeks. Sterile amber coloured bottles were used to collect 10 replicate borehole water samples from the mainland and fixed with concentrated H2SO4. Samples were transferred to the laboratory in iced coolers and analyzed using Gas chromatography coupled with Flame Ionization Detector (GC-FID). The interactions of the PAH components detected was determined using the Pearson product moment correlation coefficient (r) while spatial variance equality in means of concentrations was explored with the One-way ANOVA. Structure detection of observed inequalities was made with means plots. Concentrations of the PAHs were high and exceeded the WHO maximum permissible limit of 0.002mg/l in drinking water. Benzo(b)fluoranthene, with the highest mean concentration varied between 0.00037-0.51266 (0.08117±0.03330159)mg/l, fluoranthene varied between 0.00060-0.32890 (0.0473946±0.01769877)mg/l, while benzo(k)fluoranthene with the least mean concentration varied between 0.00017-0.08478 (0.0237385±0.00610045)mg/l. However, pyrene concentration ranged between 0.00015 and 0.24757 (0.0508440±0.01859716)mg/l, benzo(a)anthracene between 0.00020-0.21972 (0.0512660±0.01688275)mg/l, and chrysene between 0.00013 and 0.16571 (0.0488975±0.01090264)mg/l. Strong associations were observed between all the PAH components measured at P<0.01. Significant heterogeneity in mean variance of the PAHs [F(211.9502)>Fcrit(3.921478)] was recorded across the sampling locations at P<0.05. Structure detection of mean difference revealed that the inequalities were most contributed in BH1, BH 2, BH 5 and BH 10, while equality in mean concentrations were observed between BH 1 and BH 4, and BH 5 and BH 6. BH 8 recorded the highest contamination level of the various PAHs due basically to its proximity to the refinery’s effluent channel. The most probable source of these PAHs is therefore the nearby Port Harcourt Refinery Company’s effluent discharges into the surrounding creeks of the mainland. This contamination is of public health concern as several PAHs are known carcinogens. It is recommended that advanced technological engineering be applied to contain the presence of these pollutants in drinking water sources of residents of the area

Evolution of Beninese Coastline from 1963 to 2005: Causes and Consequences

The coastal zone of Benin is the interface between the marine environment and the straightforward continental environment. It is constituted of sandy cords, lagoon system, lakes and flood plains. This zone shelters a population of about 3 million inhabitants that is more than 30% of the Beninese population. As all coastal regions of the world, this zone remains very sensitive to climatic changes (global elevation of the sea level, perpetual variations of the weather marines conditions) and to human activities (large inland dams, harbour infrastructures, urbanization) that drive to the rupture of the equilibrium in this coastal environment with enhanced risks of beach erosion as the main consequences. This study monitors the evolution of the Beninese shorelines around Cotonou and underlines the causes mainly human that negatively affect this naturally fragile environment. Natural factors (tempests and erosive processes) and human actions (building of the port of Cotonou (1962) then Lome (1967) and hydroelectric dams on Volta (1966) and on Mono (1987) rivers) aim the coastal evolution of the Benin. They procreate, on the sandy cords at East of ports and rivers mouths, an erosion about 10 m linked to the reduction of provisions in sand and the fragilisation of cords by farms, steps and of anarchic occupations

Community Approach to Growing Greener Cities through Self-help Street Horticultural Gardens: A Case Study of Lagos, Nigeria

The study examines residents’ concerns in greening their communities though self-help initiatives (SHI) carried out by individuals who utilise road set-backs to plant street horticultural gardens (SHG) in Eti-osa Local Government Area, Lagos, Nigeria. It purposefully administered questionnaire to managers of all SHG in the study area to establish their socio-economic characteristics, contributions to community greening and motivating factors behind their SHI. The study found that the horticulturists were nearly males (93.7%), young adults (54.0%), earning about three dollars per day (63.6%), have been in practice for more than four years (79.3%) and altogether using about 1.5% of land in the study area for SHG. A good number of them have contributed to voluntary greening of their communities through planting of trees (76.2%), hedges and shrubs (47.6%) and flowering plants (65.1%). The horticulturists’ Motivating Index (HMI) employed to know why they went into the practice revealed that they (51%) were moved by the depreciating state of urban green (HMI=2.55) and feared (46.4%) the impending ecological doom on the built environment due to lack of sufficient green space, causing global warming (HMI=2.32). This could be why the linear regression test of the preference of social to economic value of the practice of SHG in the study area has its R2 to be 0.219. This means that SHG in the area did not necessarily bring positive economic value to the horticulturists as the social value embedded in it. This study is a prove that literature and publicities on environmental effects of global reduction in green space seem to be yielding positive results in Africa as some individuals in the study area are taking into self-help initiatives in community greening, even where land seemed very scarce for such development. It concludes that literature on the subject should be more encouraged

Estimation of Water Balance of Oyan Lake in the North West Region of Abeokuta, Nigeria

The paper presents results related to water balance of the Oyan Lake in the North West in Nigeria. The catchment covering an area of 9000 km2 includes a small dam called Oyan dam having an effective watershed area of 40 km2 with a gross storage of 270 million cubic meters. Hydrology of the area was characterized on the basis of land use, rainfall, temperature, evaporation, evapotranspiration, and runoff using meteorological data. Different methods like rainfall coefficient method is used to determine monthly distribution of rainfall including rainy and dry months; Penman method to calculate evaporation from the reservoir; Thornthwaite method and Thornthwaite water balance model to determine potential and actual evapotranspiration; and runoff coefficient method to estimate runoff. The catchment is characterized by one rainy season and two dry seasons during the year. The rainy season has five months duration and dry season seven months. The mean annual rainfall of the catchment is 1015.09 mm, out of which rainy season accounts for 96.% and the dry season for 3.9%. The total annual water loss by evaporation from the reservoir is 1178.5 mm. The mean annual actual evapotranspiration for the catchment is 899.3 mm. The mean annual runoff generated from the catchment is estimated to be 822.2 million cubic meters. The amount of water that percolates into the ground in the catchment as groundwater is estimated to be about 219.9 million cubic meters, and the same at the reservoir site is 826.9 million cubic meters. The total amount of water which is actually available to recharge the groundwater within the catchment is 1046.8 million m3

Application of Harmonic Analysis in the Preliminary Prediction of Air Temperature over Lagos and Abuja, Nigeria

Harmonic Analysis technique has been employed in predicting the hourly air temperature variations over Lagos and Abuja, Nigeria. The variations in hourly air temperatures over the two stations are periodic and thus have strong tendency of being repeated the next day, if all other atmospheric variables are constant. It was observed that the variation in hourly air temperature in the two stations is dominated by the first harmonic, thus it fluctuates by one cycle with a period of 24 hours. Invariably, harmonic equations could be applied to hourly temperature prediction even on a large scale data. The maximum hourly air temperature occurred two hours on the average after the maximum solar irradiance has occurred in each station. It was found that the temperature of the air at a particular hour is dependent on that of the previous hour