SPATIO-TEMPORAL VARIABILITY ANALYSIS OF METHANE EMISSIONS FROM MUNICIPAL SOLID WASTE DISPOSAL SITES IN KANO METROPOLIS, NIGERIA
SPATIO-TEMPORAL VARIABILITY ANALYSIS OF METHANE EMISSIONS FROM MUNICIPAL SOLID WASTE DISPOSAL SITES IN KANO METROPOLIS, NIGERIA
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Date
2021
Authors
SALISU GWADABE
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Abstract
This study analzed the spatio-temporal variability in Methane emissions at ten (10) selected solid waste disposal sites in Kano metropolis. The study was conducted by applying IPCC default methodology for two seasons (wet and dry), and Crowcon – Gasman ―FL‖ for a period of four seasons of the year (cool dry season - the harmattan (January, 2018); hot dry season (April, 2018); wet season (August, 2018); .and harvest season (November, 2018) respectively. The monitoring took place in the first seven consecutive days of those months. The Crowcon–Gasman ―FL‖ monitoring was carried out during morning (0700 hours to 1000 hours‘ local time) and afternoon (1300 hours to 1600 hours‘ local time). Firstly, for each period, and over each site the monitoring was carried at about the center of each disposal site, and then one each at 100m away from the center at the four cardinal points (North, East, South, and West). This makes a total of five readings per site and per period for each observation day. The monitoring points over a disposal sites were labeled as D1, D2, D3, D4, and D5, in which D1 is the point at the center, D2 at the North, D3 at the South, D4 at the West and D5 is the point at the East. The mean of the five readings constitute the average for each site for a day and for each period of the month. The geographic coordinates of the center of the monitoring points (D1) were recorded using a portable Garmin Global Positioning System receiver. Secondly, the Methane emission level was read in a radial pattern, at 100m interval away from the center of disposal site. During the monitoring, the Crowcon – Gasman ―FL‖ was held within 30 to 60 cm above the ground surface. This is because anything above 60cm methane emission to the atmosphere decreases. The concentration of Methane emission was recorded in percentage (lower explosive limit (LEL)). Two meteorological variables considered along with Methane emission are Temperature
and Pressure, and these were measured using Kestel 400 version 3.00 handheld weather tracker. The results shown that Kuntau (5,251.13 Gg/yr.), Court Road (5,107.90 Gg/yr.), Hajj Camp (4,626.15 Gg/yr.), Maimalari (3,603.37Gg/yr.) and Ubagama (3,537.99 Gg/yr.) disposal sites recorded the highest Methane emission by means of IPCC default methodology during the wet season period, while, by means of Gasman Fl, Court Road (29% LEL Methane), Kuntau (28.25% LEL Methane), Hajj Camp (26.00% LEL Methane), Ramin Hassan (25.25% LEL Methane), and Ubagama (24.00% LEL Methane), emitted the highest concentration of Methane emission during the afternoon monitoring. Similarly, Methane emission decreased considerably according to distance travelled away from the center of the solid waste disposal sites during the morning and afternoon monitoring. The significance (sig.) value (0.000) was less than the significance level (0.05). Therefore, the null hypothesis was rejected and concluded that Methane emissions vary considerably according to distance travel away from the center of the solid waste disposal sites during the morning and afternoon period. Nevertheless, the differences in Methane emission away from center of the disposal sites between morning and afternoon period was tested using t-test, the result obtained did not showed statistically significant differences at 0.05 probability level (0.065 > 0.05). Besides, the results obtained indicated that there is no significant diurnal variation of Methane emissions, this is because the sig. value (0.074) is greater than the level of significance 0.05, therefore, the null hypothesis was accepted. Furthermore, Methane emission monitoring by means of Crowcon-Gasman Fl, varied with the seasons of the year. The highest mean value occurred during the harvest season (26.29%), whreas the least emission occurred in the cool dry season of the harmattan (12.20%). The differences in values between the seasons are statistically significant at level greater than 0.05 probability level. Likewise, the mean of modelled results by IPCC default methodology during wet and dry seasons are higher than that of direct monitoring values by means of Crowcon – Gasman ―FL‖. This is because the independent samples test shown that the significance values (0.000 and 0.001) are less than 0.05 probability level. Lastly, the correlation coefficient value of Temperature and Methane emission is positive and greatly significant (r = 0.686, sig = 0.000 < 0.05), confirming that Temperature has a significant and positive effect on Methane emissions. Conversely, the correlation coefficient value (-0.646) for Pressure and Methane is very significant, statistically (0.000 < 0.05). Unlike the trend for Temperature, the relationship is negative, thus, certifying that Pressure has a significant negative effect on Methane emissions at the sites. The study recommends for continuous monitoring of Methane emissions from the disposal sites during the harvest and hot dry seasons. Equally, the study suggested policies meant at sequestrating Methane emissions at the disposal sites, like the reuse, recycling and reduction of waste stream in the study areas.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A DOCTOR OF PHILOSOPHY IN GEOGRAPHY
DEPARTMENT OF GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT,
FACULTY OF PHYSICAL SCIENCES,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA