TEMPORAL AND SPATIAL VARIATIONS IN CARBON DIOXIDE CONCENTRATION IN SELECTED LOCATIONS ACROSS IBADAN NORTH AND IBADAN SOUTH-WEST LOCAL GOVERNMENT AREAS, NIGERIA

Abstract

There is a growing concern on the environmental effects of carbon dioxide (C0₂) emissions especially its role in climate change. In Nigeria, activities that lead to the production of CO₂ in the environment are on the increase. However, there is dearth of information on the empirical estimation of CO₂ levels in the environment. Therefore, this study was designed to determine the temporal and spatial variation in the concentration of CO₂ in Ibadan North Local Government Area (INLGA) and Ibadan Southwest Local Government Area (ISLGA) in Oyo State. An ecological design was adopted involving field measurements of CO₂ concentration. Thirteen purposively selected locations were grouped under five major CO₂ producing areas namely: Market Area (MA), Dumpsite Area (DA), Traffic Area (TA), Abattoir Area (AA) and Farmland Area (FA). A Telaire 7001 gas meter was used to measure CO₂ levels (ppm) and temperature (⁰C) in each location at three specific times of the day (7-9am, 12-2pm and 4-6pm). Measurement was carried out 3 days weekly for four consecutive weeks during the rainy season and four consecutive weeks during the dry season. Values obtained were compared with United State Environmental Protection Agency guidelines for permissible limit of CO₂ emission (1000 ppm). Descriptive statistics, t-test, ANOVA, Pearson's correlation, trend analysis and Regression were used for data analysis at p=0.05. Mean CO₂ levels for the total time of sampling was 351.05 ± 62.9 ppm. Mean CO₂ level during the rainy (370.22 ± 62.84 ppm) and dry (331.50 ± 56.86 ppm) seasons varied significantly. Mean CO₂ levels across the 7-9am, 12-2pm and 4-6pm periods was 384.45±68.75 ppm, 352.57 ± 51.56 ppm and 315.49 ± 46.12 ppm respectively. There was a significant difference between the mean CO₂ levels across the periods. The highest mean CO₂ level was obtained in the 7-9am period. The mean CO₂ level across the five areas also varied significantly as follows TA (361.54 ± 70.89 ppm) > FA (337.64±57.36 ppm) > AA (345.78 ± 60.64 pm) > DA (338.64 ± 54.75 ppm) > FA (337.64 ± 50.77 ppm). The mean CO₂ level in INLGA and ISLGA were 351.15 ± 65.29 ppm and 350.96 ± 60.94 ppm respectively. The peak CO₂ levels for the rainy (432.2 ± 62.9 ppm) and dry (360.8 ± 64.1 ppm) seasons were obtained at TA and AA respectively. The CO₂ concentration varied significantly across locations and over time. There was negative correlation between CO₂ and temperature in both seasons (r = -0.323). A wide temporal and spatial variation of carbon dioxide emission existed among selected locations across Ibadan North Local Government Area and lbadan Southwest Local Government Area during both seasons. However, the mean carbon dioxide Ievels were within acceptable limit. Routine monitoring of CO₂ is recommended to ensure that emissions do not exceed the permissible limit.