ABSTRACT
This research work monitored levels of greenhouse gases in ambient air of Kano metropolis. Carbon monoxide (CO), Hydrogen sulphide (H2S), Nitrogen (IV) oxide (NO2), Sulphur (IV) oxide (SO2) and Methane (CH4) are the priority greenhouse gas pollutants whose concentrations were monitored in the morning and evening every month for the period of one year covering the four seasons. The sampling frame consists of eleven major traffic points within urban Kano namely; Aminu Kano Teaching Hospital/Kwandila Housing Estate (LN1), Zoo road/Aliyu bn Abu Talib Mosue (LN2), Court/France roads (LN3), Igbo road/Sabon gari Market (LN4), Kofar Nasarawa (LN5), Rimi Market/Murtala Hospital (LN6), Dan – Agundi/B.U.K. (LN7), Kofar Mazugal/Abatoir (LN8), Airport/Zungeru roads (LN9), Sani Abaca/Murtala Mohd roads (LN10) and Environmental Pollution Control Laboratory/Wazobia Radio junction (LN11) which serve as control. An automatic monitoring systems with certificate number EX 93C 2069X and EX 93Y 2078X for ‗TO‘ and ‗FL‘ respectively was used to monitor the concentrations of these greenhouse gases. Traffic count was conducted to obtain the statistics of motorcycles, tricycles, cars and trucks movement in the various sampling traffic points. The results obtained show that the mean level of greenhouse gases in the morning (7:30 – 9:30 am) sampling hours were 5.75 ± 1.11, 1.39 ± 0.77, 0.20 ± 0.13, 0.09 ± 0.11, and 0.19 ± 1.38 ppm for CO, H2S, NO2, SO2, and CH4 respectively. For evening (4:30 – 5:30 pm) hours the mean levels of these gases were 15.64 ± 1.56, 3.22 ± 3.05, 2.42 ± 4.32, 0.14 ± 0.10, and 0.76 ± 0.53 ppm for CO, H2S, NO2, SO2, and CH4 respectively. The mean level of greenhouse gases in the evening is higher than the FEPA established guideline of 10, 0.06, 0.04 – 0.06, 0.06 and 0.06 ppm for CO, H2S, NO2, SO2 and CH4 respectively. The higher mean level of the
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greenhouse gases in the evening at site 5, 5, 6, 6 and 7 can be attributed to the high traffic density at the sites. The four seasons monitoring results revealed that CO is far higher than all other gases across the sites. The next higher was hydrogen sulphide. The next higher to H2S were NO2, SO2 and CH4 during dry and (warm,cool) and wet and warm seasons. The mean levels of greenhouse gases were noticed to be very low both in the morning and evening during dry and hot and wet and warm seasons. This could be attributed to the shorter sunshine period and lower temperature which predetermined decomposition/burning of organic matters. Comparison of the Air Quality Index level (AQI) revealed that the values were in the range of CO moderate at roads junctions 1, 3, 4,6,8,9 and 10 to good at locations 2, 7 and 5 during both hours of sampling, NO2 was very low at all road junctions except 11 which is very good whereas, H2S and SO2 values were very good in the morning. Statistic analysis of mean level of greenhouse gases across the eleven sampling locations has shown a normal distribution with remarkable variations and of significance difference at p ˂ 0.05. The correlation studies showed that there is high correlation of 0.909 between H2S and CO and 0.864 between SO2 and H2S indicating that they could be from the same source. The research generally established that motor cars are the predominant source of these greenhouse gases emissions as shown by the significant correlation of 0.603, 0.677 and 0.689 for CO, H2S and SO2 respectively and volume of cars.
TABLE OF CONTENTS
Title Page——————————————————————————i
Approval Page————————————————————————ii
Declaration—————————————————————————-iii
Certification—————————————————————————iv
Dedication—————————————————————————–v
Acknowledgements——————————————————————vi
Abstract——————————————————————————–vii
Table of Contents———————————————————————vii
List of Tables————————————————————————–ix
List of Figures ————————————————————————x
List of Appendices ——————————————————————-xi
Abbreviations, Definitions, Glossary and symbols ——————————xii
1.0 INTRODUCTION– ——————————————————-1
1.1 Atmosphere——————————————————————1
1.2 Greenhouse Gas Inventory in Nigeria———————————-14
1.2 Statement of the Problem————————————————-16
1.3 Justification——————————————————————16
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1.4 Aim and Objectives——————————————————–18
2.0 LITERATURE REVIEW
2.1 Urbanization and Population growth in Developing
Countries———————————————————————19 2.2 Traffic Emission in Developing Countries—————————–20
2.3 Traffic Emissions in Nigerian Cities————————————-22
2.4 Sources of Greenhouse Gas Pollutants———————————-31
2.4.1 Anthropogenic (Human Activity source) ———————————31
2.4.2 Natural source—————————————————————–32
2.5 Direct Greenhouse Gases————————————————–32
2.5.1 Water vapour——————————————————————32
2.5.2 Carbon (IV) oxide————————————————————34
2.5.3 Methane————————————————————————38
2.5.4 Nitrous oxide——————————————————————44
2.5.5 Halogented gases————————————————————–48
2.6 Indirect Effect Greenhouse Gases——————————————49
2.6.1 Carbon (II) oxide—————————————————————49
2.6.2 Nitrogen (IV) oxide————————————————————53
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2.6.3 Sulphur (IV) oxide————————————————————-55
2.6.4 Hydrogen sulphide————————————————————-60
2.7 Effect of Greenhouse Gas Emissions—————————————-62
2.7.1 Greenhouse effect—————————————————————62
2.7.2 Global warming—————————————————————–63
2.7.3 Acid rain————————————————————————-64
2.7.4 Climate change—————————————————————–66
2.8 Solid Waste and Environment————————————————71
3.0 MATERIALS AND METHOD———————————————74
3.1 Materials————————————————————————–74
3.2 The Study Area—————————————————————–74
3.3 Climatic condition————————————————————–75
3.4 Sampling Locations————————————————————76
3.5 Theoretical Frame work——————————————————76
3.6 Euipment————————————————————————-79
3.7 Data Collection—————————————————————–79
3.8 Instrumentation—————————————————————-80
3.8.1 Crowcon – Gasman————————————————————80
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3.8.2 Caliberation———————————————————————81
3.8.3 Operation———————————————————————–83
3.9 Method—————————————————————————83
3.10 Statistical Analysis————————————————————84
4.0 Results—————————————————————————-85
4.1 Grenhouse Gases Levels of the Eleven Sampling Sites—————–85
5.0 DISCUSSION——————————————————————-125
5.1 General Discussion————————————————————-125
5.2 Morning (7:30-9:30 am) and Evening (:30-5:30 pm)
Sampling Periods————————————————————–126
5.2.1 Carbon (II) oxide————————————————————–127
5.2.1 Hydrogen sulphide————————————————————128
5.2.3 Nitrogen (IV) oxide————————————————————130
5.2.4 Sulphur (IV) oxide————————————————————-131
5.2.5 Methane————————————————————————-132
5.3 Statistical Analysis————————————————————-134
5.4 The levels of Greenhouse Gases along Sampling Sites during
the four seasons——————————————————————137
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5.4.1 Carbon (II) oxide————————————————————–137
5.4.2 Hydrogen sulphide————————————————————140
5.4.3 Nitrogen (IV) oxide———————————————————–141
5.4.4 Sulphur (IV) oxide————————————————————-142
5.4.5 Methane————————————————————————–144
6.0 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS—-150
6.1 Summary————————————————————————-150
6.2 Conclusions———————————————————————-151
6.3 Recommendations————————————————————–152
REFERENCES———————————————————————–156
APPENDICES————————————————————————179
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CHAPTER ONE
1.0 INTRODUCTION
1. 1 Atmosphere
Earth is the right planet of our solar system to life in being wrapped in a thin layer of gaseous envelope that is chemically active and rich in oxygen known as atmosphere. The earth‘s atmosphere acts as an insulating blanket, trapping sufficient solar energy to keep the global average temperature in pleasant range. The blanket is a collection of atmospheric gases called ‗‘greenhouse gases‘‘. Greenhouse gases are gaseous compound found in the earth‘s atmosphere that trap heat and contribute appreciably to the warming of the earth habitat. An increase in the concentration of greenhouse gases would result in the greater retention of infra-red radiation in the atmosphere and this give rise to the phenomenon known as greenhouse effect (Hill, 1992; NEST, 2001; Zumdahl, 2002).
The term greenhouse effect is a progressive warming up of earth‘s surface due to blanketing effect of man-made greenhouse gases in the atmosphere. It is a phenomenon whereby greenhouse gases create a condition in the troposphere causing a trapping of heat and leading to increased surface and lower tropospheric temperatures (Tawari and Abowei, 2012). Greenhouse effect means the excessive presence of those greenhouse gases that blocked in the infra-red radiation from the earth‘s surface to the atmosphere leading to an increase in temperature, which in turn would make life on earth difficult (Chitkara, 1982). Ultimately, more greenhouse gases means more infra-red radiation trapped and held which gradually increases the temperature of the earth‘s surface and the air in the lower atmosphere.
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Figure 1.1: The Natural and Human Enhanced Greenhouse Effect.
Source; from Google image of greenhouse effect
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About 30% of the sunlight that beams toward the earth is deflected by the outer atmosphere and scattered back into space. The rest reaches the planet‘s surface and is reflected upward again as a type of slow moving energy called infra-red radiation. Some amount of this infra-red radiation (heat) is absorbed by greenhouse gas which causes the weakly held molecules to vibrate and emit heat to another gas molecule which re-emitted heat in to the earth‘s surface. This emission – re-emission process has been sufficient to raise the average temperatures at the surface by about 33OC (59OF) above what it would otherwise have been. Without the natural greenhouse effect, life on this planet would probably not exist as the average temperatures of the earth would be chilly –18OC, rather than the present 15OC and water would have been present as ice. The natural greenhouse effect allowed liquid water to remain stable over most of the earth‘s surface, this provide the fundamental substrate for biological activity (Mintzer, 1993 and Pidwirny, 2006).
This greenhouse effect has been understood by scientists for about a century and technological advancements during this period have helped to increase studies on the phenomenon. Greenhouse effect was understood as natural process that aids in the heating of the earth‘s surface and atmosphere. Therefore, it is an essential environmental prerequisite for life as it keeps the earth‘s climate warm and habitable. Currently, the problem is understood as man-made activities that distort and accelerate the natural process by creating more greenhouse gases in the atmosphere than are necessary to warm the planet to an ideal temperature. It is as a result of the fact that carbon (IV) oxide is the single most important greenhouse gas accounting for about half of all current addition to the greenhouse effect. Other gases, such as methane,
4
nitrous oxide, chloroflouro carbons (CFCs), ozone also contribute to the greenhouse effect and certain traces of anthropogenic atmospheric gases, sulphur dioxide (SO2), carbon monoxide (CO), nitrogen dioxide (NO2), hydrogen sulphide (H2S) and ammonia (NH3) although make up only a one percent of the total atmosphere, they are able to pchange the energy balance of the planet by helping in the decomposition or building of major greenhouse gases (Pidwirny, 2009).
According to British Broadcasting Corporation greenhouse effect refers to circumstance where the short wavelengths of visible light from the sun pass through a transparent medium and are absorbed, but the longer wavelengths of the infra-red re-radiation from the heated object are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and higher resultant temperature. Broadly speaking greenhouse effect is used to describe the trapping of an excess heat by raising the concentration of greenhouse gases in the atmosphere. Water vapour provides the majority of the natural greenhouse effect with fewer contributions from carbon (IV) oxide, methane, nitrous oxide and ozone.
These gases form a blanket around the earth that lets the incoming sun rays to pass through but blocks the reflected heat rays from going out into the space. They keep the earth‘s surface and lower layers of the atmosphere warmer, and the upper layers cooler, than if the greenhouse gases are not there.
About 80-90% of the earth natural greenhouse effect is due to water vapour and clouds. Most of the rest is due to carbon (IV) oxide, methane and a few other minor gases. While the remaining gases in the atmosphere such as carbon (II) oxide, sulphur
5
(IV) oxide, nitrogen (IV) oxide, ammonia and hydrogen sulphide also absorb and emit a small amount of infra-red radiation, their radiative effect on temperature is so weak that they can be neglected, but however they help to build or in the decomposition of other greenhouse gases. Among the major greenhouse gases methane is much more potent than carbon (IV) oxide, there is far less of methane in the atmosphere and its concentration in the atmosphere is increased due to the presence of carbon monoxide that reacts with atmosphere hydroxyl radicals (OH-) (Yusuf and Oyewunmi, 2008).
However, today the concentration of carbon (IV) oxide is increasing, due to the burning of fossil fuels and forest. Compared to a pre-industrial atmospheric concentration of 270 ppm, the average concentration has increased to close to 400 ppm in 2012. The causes of the man-made portion of the greenhouse effect, is believed to be responsible for the global warming of the last fifty years or more. Also the concentration of methane, although extremely small has also increased in recent decades contributing somewhat to the strengthening of greenhouse effect.
The mechanism of greenhouse effect involves energy from the sun passes through the atmosphere; a portion of the energy (about 26%) is reflected or scattered back to space by clouds and other atmospheric particles. About nineteen percent of the energy available is absorbed by clouds, greenhouse gases such as ozone and particles in the atmosphere. The remaining fifty five percent (55%) of the solar energy passing through the earth‘s atmosphere four percent is reflected from the surface back to space. On average about fifty one percent (51%) of the sun radiation reaches the surface. The energy is then used in a number of processes, including the heating of the ground
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surface; the melting of ice and snow and the evaporation of water and plant photosynthesis.
The heating of the ground by sun energy causes the earth‘s surface to become a radiator of energy in the long wave band (infra-red radiation). This emission of the energy is generally directed to space. However, only a small portion of this energy actually makes it back to space. The majority of the outgoing infra-red radiations absorbed by greenhouse gases are used to warm the planet earth. Absorption infra-red radiation by the atmosphere causes global warming of the Earth‘s surface through the atmospheres trapping of outgoing infra-red radiation (Jessica and Stephen, 2007).
One of the first scientists to conceive the greenhouse effect were French Physicist and mathematician Jean Batise-Joseph Fourier who compared the effect with a horticultural hot house or greenhouse. The term has persisted to date, even though the greenhouse analogy is actually poor one. A greenhouse keeps plants warm by letting sunlight in while preventing out (0ghifo, 2011).
The greenhouse effect is important as it keep the Earth warm enough to sustain life. However, if it gets too warm, it could endanger all life on the planet Earth. Human activities, especially agriculture and industrial have increased the emission of greenhouse gapses and these gases led to the progressive depletion of ozone layer in the stratosphere (Olufemi and Samson, 2010). The ozone layer is the shield that absorbs about 90% of the harmful electromagnetic energy emitted by the sun on the earth. The abundance of greenhouse gases accentuates the effect globally, thus causing global warming.
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During the last 150 years there has been a rise in greenhouse gases concentrations. This has been due largely to the rapid growth in population which increased the number of things like housing, clothes, and cars and air conditions resulting in vast stretches of deforestation and more industries. A large number of new cars rolling out on the road every year contribute to air pollution caused by burning petrol and diesel. Fossil fuels like petroleum and oil, wood and gas are being consumed heavily for industries and domestic purposes. Industries release a large amount of pollutants not only in the atmosphere, but also in rivers and oceans.
Major greenhouse gases such as carbon (IV) oxide (CO2), methane (CH4) water vapour and nitrous oxide (N2O) occur naturally and from fuel combustion in the atmosphere while chloroflourocarbons (CFCs), hydroflourocarbons (HFCs) and perflourocarbons (PFCs) as well as sulphur hexafluoride (SF6) are solely man-made (Kellog, 1996). Other gaseous compounds that are produced by the process of internal combustion engines that burn gasoline or other fossil fuels are carbon (II) oxide, hydrogen sulphide, nitrogen (IV) oxide and sulphur (IV) oxide have continue to pose significant threats to human health and gradual warming of the earth‘s surface. They caused indirect effects on global warming through the build up or decomposition of major greenhouse gases in the atmosphere which leading to increase in the earth‘s average temperature (Yusuuf and Oyewunmi, 2008: Wang, et al., 2011). Though is insignificant but can cause changes in the air quality over a period and can be attributed to the human activities (Karen, 2008).
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The Global warming and climate change have been described as the greatest threat facing humanity. The challenge before scientist is how to prevent the earth from global temperature rise on further emissions of greenhouse gases and high risen of temperature changes are likely to be so extreme thus, would be difficult to cope with would produced more instance and frequent extreme weather events, melting the ice in the atmosphere and thereby increasing the volume of water on the earth that may result into flood, sea level could raise as much as one meter and hurricane as seen in the United State of America (Karen, 2008). This was the basis for the creation of world bodies such as International Panel on Climate Change (IPCC) in 1988; by the United Nation Environmental Protection Agency (UNEPA) and World Metrological Organization (WMO) and the United Nation Framework Convention on Climate Change (UNFCC) which Nigeria has also signed in 1995 at Rio de-janeiro in Brazil (Madugu, 2009).
Climate change refers to as any significant change in measures of climate such as temperature, precipitation, or wind lasting for an extended period. It is a permanent departure of climate patterns from mean value of observed climate indices (Chikaire et.al, 2006). The United Nations Framework Convention on Climate Change (UNFCCC) defines climate change as a change of climate which is attributable directly or indirectly to human activities that alter the composition of the global atmosphere and which are in addition to natural climate variability observed over a comparable time periods (Intergovernmental Panel on Climate Change [IPCC], 2001).
According to Odjugo (2011), climate changes are caused by both natural (biogeographically) process and human (anthropogenic) activities. He further identified
9
natural processes as (i) astronomical factors such as the eccentricity of earth‘s orbit, obliquity of ecliptic and orbital processions; and extraterrestrial; factors such as the quality of and quantity of solar radiation variations and volcanic eruptions. Li (2009) observed that up to 1950, natural factors particularly solar radiation variations and volcanic dust was the predominated factor of temperature change. However, recent studies have shown that the heightened incidence of climate change across the globe is as a result of aggressive and unsustainable human activities that are associated with population growth, urbanization, gas flaring, mechanized life styles which take place on domestic and industrial scale. The quantum energy consumed and harmful gases released from these activities have been identified as a major factor accelerating atmospheric global warming or climate in recent times (Guiness and Nagle, 2006: Bello et.al, 2008 and Iwejingi, 2013). The most important of activities that generate emission of greenhouse gases which alter the Earth‘s radiation balance are; burning of fossil fuels, deforestation, uncontrolled grazing, livestock migration and growing of population also posed threat to the environments (Bello et.al, 2008).
The IPCC (2007) asserted that global greenhouse gas released via human activities have increased by 70% from 1970 to 2004. Ozor (2009) defined climate change a change in climate over time, whether due to natural variability or as a result of human activity and is widely recognized as the most serious environmental threat facing our planet today. Ozor emphasized threat posed by climate change and called for the urgent need for countries to rise up to this clarion call of combating the negative effects of climate change.
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Although the length of time it takes the changes to manifest matters, the level of deviation from the normal and its impacts on the ecology are most paramount. Climate change is the end product of a changing climate (Odjugo, 2011). Climate change is said to exist when the level of climatic deviation from the normal is very significant over a long period of time preferably thirty to thirty five years and such deviations have clear and permanent impacts on the ecosystem. Climate therefore refers to the characteristics condition of the atmosphere deduced from repeated observations and averaging the weather of a region over a long period of time, such as thirty years.
Many developing countries have experienced a progressive degradation in air quality as a consequence of rapid development over last three decades (Agrawal et al., 2003). Nigeria as developing country in the world would not be exempted from the global effect, as Nigerians economy today heavily dependent on the oil sector, which account for around eighty percent (80%) of government revenues (Ekeme, 2007). This is particularly problematic because fossil fuels are the chief culprit implicated in the climate change phenomenon called global warming. Hence, Nigeria has begun to feel the effect of climate change as the frequency and intensity of extreme events like drought, sea level rises, prevalent infection of disease and flood have increased (Elisha, 2009: Bello et al., 2012).
One of the anthropogenic sources of greenhouse gases are products of combustion and according to USEPA (2004) the major contributing sectors are ranked in the following order; industrial, transportation, residential, commercial and agriculture. Other human activities that contribute to greenhouse gas emission include change of land use, use of fertilizer, deforestation, industrialization, urbanization and
11
poor municipal solid waste management. However, in Nigeria as well as other developing countries in the world which are not yet fully industrialized, majority of the environmental effects result from vehicular emissions, burning of solid fuels, urbanization, deforestation and growing population. Vehicular emissions were the largest source of air pollutant and therefore a large contributor to global climate change (Barth and Boriboonsomsi, 2008). Motor vehicles produced more air pollution than any other human activity (WRI, 1997). In most developing countries of the world vehicular growth has not been checked properly by environmental regulating authorities leading to increase levels of pollution (Han and Naecher, 2006). Traffic emission contributes about 50 to 80% of nitrogen (IV) oxide and carbon (II) oxide concentration in developing countries (Fu, 2001: Goyal, 2006). This situation is alarming and is predicted on the poor economic disposition of developing countries, poor vehicle maintenance culture and importation of old vehicles which culminate to an automobile fleet dominated by a class of vehicle known as ‗‗super emitters‘‘ with high emission of harmful pollutants (Ibrahim, 2009).
Ambient pollution is further compounded by rapid urbanization of many developing countries. The global urban population reached 50% in 2008 and is expected to increase to 60% by 2030. This increase will be particularly pronounced in developing countries, in which 80% of the urban population will be living in 2030 (UNEPA, 2007). Accompanying this rise in urban population will be four times increase in the number of vehicles in cities by 2050, making transport- related pollutants a hazardous even with low vehicular movement rates (World Bank, 2004). Faize and Sturn (2000) stated that in Chinese cities, concentrations of particulates and other transport-related pollutants are up to six times higher than WHO- recommended
12
guidelines, even though China only has eight vehicles per 100 persons compared to 750 vehicles per 1000 persons in U.S.A.
Kano State is among the major cities in Nigeria, its metropolis developed over the years resulting in a steady progress in industrialization, urbanization and increase in population and high traffic density. Industrially, it is one of the most developed cities in Nigeria with many industries predominantly tannery, plastics and textile industries (Faboye, 1997). The presence of raw materials, availability of markets, transportation networks, capital and labour made Kano metropolis one of the major industrialized cities in Nigeria. The aforementioned factors resulted in a rapid population growth especially through migration (Malumfashi et al., 2011). The growth in population and the collapse of public transport services has led to motorbike taxis being adopted as a mean of intercity and intracity transport, increased in economic activities leading to more automobiles, extensive urbanization and indiscriminate refuse disposal which decompose to a number of gases such as hydrogen sulphide and methane that have aggravated the problem of ambient air quality (Otti et al., 2011; Okunola, et al., 2012).
The air along the intersections of selected roads where majority of people reside along the busy roads every day either to do their work or sell their wares could hardly be regarded as clean due to pollutants emission from various activities along the roads intersection. Therefore, the ill-effects on health due to air pollution resulting from automobile exhaust emission must be very serious indeed (Ayodele and Bayero, 2009).
Much attention is given to general industrial pollution and pollution in gas flaring, with little reference given to damage caused by vehicular emission major sources of gases which are the causative agent of global warming. Koku and Osuntogun
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(2007) studied three cities in south west region of Nigeria: Lagos, Ibadan and Ado-Ekiti which have significant air quality pollution. Air quality indicators CO, SO2, NO2 and total suspended particles (TSP) were determined. The results of CO, SO2, NO2 and particulate count per minute were higher than FEPA limits. Their conclusions showed a growing risk of traffic-related problems in these cities and hence recommended serious air quality measures.
Moen (2008) carried out a study in which ambient air hourly concentrations for CO, NO2 and SO2 at six major intersections in Abuja was monitored during morning low traffic hours and during afternoon, high traffic hours. The findings served as a model of exposure for traffic wardens whom are high exposure group. The results showed that vehicle emissions are having a negative impact on air quality, and that traffic wardens have high prevalence of symptoms that are possibly related to and are exacerbated to vehicle emission. He clearly recommended that air quality management should be a greater priority in Abuja and the effect of vehicle emissions on air quality and health should be studied further.
Oguntoke and Yusuuf (2008) carried out a study on air pollution arising from vehicular emission and the associated human health problems in Abeokuta metropolis, Nigeria. Their assessment on the level of some selected air pollutants which are largely products of internal combustion engines namely CO, NO2, SO2, H2S and CH4 demonstrated that vehicular emissions contribute significantly to urban air quality.
Kumar et al., (2011) in a study of ambient air quality status in Japur city (Raasthan, India), using AQI reported that the level of air pollutants in the cities vary with climatic conditions and are higher in winter season.
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1. 2 Greenhouse gases inventory in Nigeria
Article 4 of the United Nation Framework Convention on Climate Change (UNFCC, 2005) requires each party to periodically report the emissions of greenhouse gases including CO2, CH4, N2O and non-methane volatile organic compounds (NMVOC) in their National Communication. In fulfillment of the article, Nigeria‘s national communication based on emission per unit human population (based on gross population of 96.7 million for the year 1994) indicates gross per capita CO2 emission of 0.5tC/cap. Per capita, non CO2 greenhouse gas and precursor gases are between 2 to 4 orders of magnitude lower than CO2 per capita emissions.
An overview of gross carbon emission by sources and removal by sinks indicates gas flaring, transportation, and electricity generation as the most significant energy consumption process leading to greenhouse gas emissions. Energy and land use change sectors were the main contributors to carbon (IV) oxide emissions, while energy, agriculture and solid waste are the main contributors to methane emissions.
The total methane emission in Nigeria is 5.9Tg methane (Sodangi et al., 2011). The energy production and consumption sector with a total emission of 1.48Tg-CH4 contributed 25% of gross national emissions with agriculture contributing the rest. Municipal solid waste and waste water treatment contributed 0.21 and 1.88Tg CH4. These respectively represent 4 and 32% of gross national emissions. The gross emission of nitrous oxide (N2O) was 11.95Gg N2O. The energy sector petroleum refining, small combustion and transportation sub-sectors generated 7.47Gg N2O representing 63% of gross national emissions for the year. This was closely followed by emissions from savannah burning (28%), field burning of agricultural waste (6%),
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burning of solid waste (2%) and biomass burning from forest conversion (1%) (Nabegu, 2011).
The total CO2 emission was 17.05Tg CO2. Out of these, the energy sector generated 13.1Tg CO2 with the following major energy sub-group emissions: transport 4.73Tg CO2 or 28% of the gross national emissions; small combustion sources and gas flaring each representing about 25% of the gross national CO2 emissions. The agricultural sector emitted 3.59Tg CO2 or 28% of the gross national emissions for 1994, while the other energy sub-sectors, solid waste and land use change emitted 33.2Gg CO2, 171Gg CO and 162Gg CO2 (Nabegu, 2011).
The total generation of greenhouse gases based on the current data for Nigeria is low when compared to emissions from United State and other developed economies. However, Nigeria‘s gross emissions may approach those of these countries if its population continues to grow at the current rate of 3.5% per annum since per capita emissions is also likely to increase. The current population of Nigeria is estimated to 140 million representing 20% of the entire population of Africa. The United Nations population projected a population of 289 million for Nigeria by 2050. Apart from population growth, Nigeria has been experiencing urbanization over the last five decades. The proportion of the population living in the urban centers has risen from 15% in 1960 to 43.3% in 2000 and is projected to rise to 60% by 2015 (NPC, 2004). Furthermore, current economic growth of 7% per annum since 2005 has been projected to continue and would invariably fuel increase in the generation of solid waste and fossil fuel combustion (Nabegu, 2011).
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1. 3 Statement of the Problem
Nigeria as a developing country in the world is experiencing an adverse global warming and climate change with negative impact on the welfare of its people; such as persistent droughts and flooding, and alteration of precipitate levels. Deforestation which is the common act in Nigeria result in the decay of a lot of plant matter, contributes to the greenhouse effect by releasing of carbon contained in cut trees and reduction in the ability to reduce carbon (IV) oxide from the atmosphere through photosynthesis which in turn affect crop‘s yield.
Kano state is one of the hottest states in Nigeria which made the inhabitant to be at risk of hot climatic condition, malaria, meningitis and many other diseases. Kano metropolitan is highly populated and is currently at the risk of global warming due to emission of gaseous pollutants on daily basis and from vehicular emission and other anthropogenic activities.
1. 4 Justification
Naturally, greenhouse gases in the atmosphere play a key role of regulating the temperature of the earth by trapping some of the heat radiating from the surface and transferred to the atmosphere. As a result of photosynthesis and other regulatory processes, the concentration of greenhouse gases present in the atmosphere is kept constant. However, today the various forms of anthropogenic activities have resulted into a considerable increase in the atmospheric concentration of greenhouse gases and consequently, accelerated the rate of climate change and global warming.
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Most of the world has already being affected by climate change across all the continents and this has resulted in adverse impact on their development in such sectors as agriculture, water quality, increasing population and health (IPCC, 2001). Nigeria as pa developing nation is also experiencing an adverse climate conditions with negative impacts on the welfare due to rapid increase in population without considering the limited resources in the following ways.
(i) persistent droughts and flooding, off season rains and dry spell have sent growing
seasons out of orbit, on a country dependent on a rain fed agriculture,
(ii) lakes drying up and a reduction in river flow in the arid and semi arid region due
overexploitation of the natural resources without renewability (resource
maitanance),
(iii) increasing carbon dioxide and carbon fluoro carbons level in the atmosphere due to
human activities promote global warming and hinder the normal rainfall,
(iv) extinction of animal and plant species as the pace of change in habitat driven by
global warming outstrips their ability to adjust,
(v) winds blowing at increasing intensity and frequency along the sahara and sub-
saharan region in north-eastern parts Nigeria, thereby making agriculture to be
difficult, and
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(vi) Biodiversity change cause by excessive use of living things (plants and animals) by
human activities due population increase.
1. 6 Aim and Objectives
The aim of the present study is to evaluate the present levels of greenhouse gases in the ambient air at intersections of selected roads in Kano metropolis, Nigeria.
The specific objectives are:
(i) Determining the levels of greenhouse gas (CO, H2S, NO2, SO2 and CH4) in the
ambient air at the intersections of selected roads in Kano metropolis, Nigeria.
(ii) Comparing the concentration recorded with standard limits (WHO, FEPA and
USEPA) to identify potential risks to human being and environment.
(iii) Establishing a relationship between pollutants and vehicular emissions.
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