CHAPTER ONE
1.0 INTRODUCTION
The presence in the air of one or more contaminants in such a concentration and of such duration as to cause a nuisance or to be injurious to human life, animal life or vegetation.
1.1 BACK GROUND OF STUDY
Through many interactions, the composition and chemistry of the atmosphere are inherently connected to the climate system since atmospheric pollutants initiate chemical reactions affecting the climatically important compounds such as greenhouse gases. Therefore, when considering climate chemistry interactions in the atmosphere, it is not only important to study the emissions of the climate compounds, but also to consider the chemical processes and the distribution of the compounds in the atmospheric regions by assessing their atmospheric sources and fates and determining their lifetimes. A considerable amount of kinetic studies has been carried out in this field. Consequently, progressive improvements in the database for reactions involving atmospheric pollutants and the quantification of their atmospheric lifetimes are made. This is fundamental to understanding the relationship between the budget and the trends of atmospheric pollutants and thus, their impact on the climate. This issue is an essential step helping to develop effective control strategies and to establish appropriate legislations in order to prevent the emission of pollutants and to protect the atmosphere. In this respect, this paper focus on the impact of the gas phase chemistry on the climate and briefly presents the future changes in the Mediterranean climate. The major kinetic methods used in this field in laboratory studies are then reviewed and emphases on their limitations are indicated. Kernerman English Multilingual Dictionary (2010) define environment as the sum total of all surroundings of a living organism including natural forces and other living things which proceed conditions for development and growth as well as of danger and damage. The environment therefore is liberty the entity on which we all subsist and on which over endive agricultural and industrial development depend we occupy the biosphere a tin layer of land, air and water on the surface of the plant the environment contains all the resources, both renewable and non-renewable that men will never need for survival on the plant. Pollution is the introduction of contaminations into a natural environment that causes instability disorder, harm or discomfort to the ecosystem i.e physical systems or living organisms (from the Merriam Webster online dictionary http. // www Merriam Webster com/dictionary/pollution). Pollution can take the form of chemical substances or energy such as noise or light, pollutions, can be either foreign substances/energies or naturally occurring contaminants pollution D often classed as point source or nonparty source.
1.2 STATEMENT OF PROBLEM
Effect of pollution to man in his environment a case study of IkpobaOkha Local Government Area in Edo State is about the diverse ways pollution his affected the people living in that location in Edo State due to urbanization, construction of industries lack of health education to enable them know the way to keep their environment clean. However, suggestions on possible ways of scaling the problems to enable the inhabitants of the area live in a healthy atmosphere were highlighted.
1.3 OBJECTIVES OF THE STUDY
The objective of the study includes the following:
1 To examine the effects of pollution to man and his environment
2 To identify the various sources of pollution
3 To suggest solutions to pollution problem in the area of study
4 To define the term pollution
1.4 SIGNIFICANCE OF THE STUDY
This study will create awareness on what pollution is all about it’s effect to man and his environment it will suggest possible ways on how to educate people on the control of pollution that bring ablaut pollution in the environment the study will also enlighten the populace on the dangers of pollution and also server as a reference to other researchers and the government
1.5 RESEARCH QUESTION
The following research questions were formulated for the study
- Does the present of industries is residential area encourage pollution
- Does traffic confection increase release of pollutions?
- Does health education about the defers of pollution help to reduce pollution and its effect on men?
- Does indiscriminate burning of bushes and refuse disposal cause pollution
- Does urbanization cause increase in pollution?
1.6 SCOPE OF THE STUDY
The scope of the study is Benin City and the proposed areas for the research are communities in IkpobaOkha Local Government Area in Edo State respondents will include residents at Oregbeni community Aduwawa community and Engaen community.
1.8 DEFINITIONS OF TERMS:
Aesthetic: this is concerned with beauty and art, and the under standing of beautiful things
Aquatic: giving or living in on or near vector aquatic plats.
Biodegradation: an act of substance of chemical to changed back to a harmless natural state by the action of bacteria and will therefore not damage the environment
Bacteria: is the simplest and smallest forms of plant life they exist in larges numbers in air, victor and soil and also in living and dead creature and plants and are often the cause of disease
Community: all the people who live in a particular area
Contaminates: substance that make the air impure or vector impure
Dissolve: of a solid to Mize with a liquid and become part of it
Environment: the is the natural world in which people animals and plants live
Clarions: a Lange mass of ice, formed by snow on mountains that mores very slowly down a valley
Metal: a type of solid miners substance that is usually hand and shim and that and electricity on travel through e.g tin, Iron and gold
Ozone larger: a layer of Ozone high above the earth’s surface that helps to protect the earth from the sun’s harmful rays
Pathogens: this is a thing that causes disease
Renewable: to begin again after praise or an interruption
Smoker: the is a discharge or f fume from automobile and industries and emission from bush burring
Termed pollution: this is a temperature charge in natural water bodies caused by human influence, such as use of victor as coolant in a power plat
Ventilation: a allow fresh air to enter and move around a room building e.t.c
CHAPTER TWO
REVIEW OF LITERATURE
The related literature to this study is discussed under the following sub headings:
Conceptual Framework
Concept of Climate Change
Ecological Effects of climate change
Concept of Impact and Impact studies
Agricultural Production in the Niger Delta region of Nigeria
Adaptation Strategies for Coping with the Impact of Climate Change on Agricultural Production in the Niger Delta region of Nigeria
Theoretical Framework
The Anthropogenic Global Warming Theory
The Planetary Processes Theory
Ecological Systems Theory
Concept of Climate Change
Climate is the weather condition of an area over a number of years (Mama &Osinem, 2007). It is the regular pattern of weather conditions of a particular place. The Intergovernmental Panel on Climate Change (IPCC, 2007) glossary definition shows that:
Climate is the average weather within a given duration. It is the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is usually 30 years and the quantities are most often surface variables such as temperature, precipitation and wind.
Climate is the typical weather conditions experienced at any location or area over series of years. Weather conditions such as rainfall, sun intensity, surface temperature and other meteorological elements recorded on interval for years and the average taken at the end of the targeted period is referred to as the climate of the location where such data were collected. Over historical time span, there have been a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water, and proximity to oceans and mountains (IPCC, 2007). Many global issues are related to climate, such as the supply of basic needs such as food, water, health, and shelter. Unfavorable climate variations may threaten basic needs with increased temperatures, sea level rise, changes in precipitation, and more frequent or intense extreme events (Karl, Melilla, & Peterson, 2009). It is predicted that food security, water and other key natural resources may be threatened by climate change.
Climate change is the significant and lasting variation in the statistical properties of the average weather system when considered over long period of time, regardless of cause (IPCC, 2007). Climate change can be referred to as the variation in average weather which is attributed directly or indirectly to human activities in addition to natural events that alters the composition of the atmosphere over comparable time period. The term is sometimes used to refer specifically to climate variation caused by human activities, as opposed to earth’s natural processes (United Nations, UN, 1994). Climate change is a long-term shift in the weather condition of a specific location, region or planet. The shift is measured by changes in features associated with average weather, such as temperature, wind patterns and precipitation (UN, 1994). It could be a shift in average weather conditions, or in the distribution of weather around the average conditions (IPCC, 2007). In the context of environmental policy, the term climate change has become synonymous with anthropogenic global warming, which is the rise in average surface temperature (IPCC, 2007). Global warming is the heating of the earth’s surface which results when the atmosphere traps heat radiating towards space (Oreck’s, 2004). Global warming summarizes the term referring to the increase in the surface temperature of the earth. Climate Change includes global warming and everything else affected by increasing greenhouse gases (GHG) level (IPCC, 2007). When the average weather of a specific region is altered between two different time periods, then climate change is said to have occurred (Peterson, 2009).
Climate change usually occurs when there is an alteration in the total amount of the sun’s energy absorbed by the earth’s atmosphere and surface. It also happens when there is a change in the amount of heat energy from the earth’s surface and atmosphere that escapes to space (the area beyond earth’s atmosphere) over an extended period of time (National Snow and Ice Data Center, NSIDC, n.d). An area’s climate is generated by the average weather system, which has five components: atmosphere, hydrosphere, cry sphere, land surface, and biosphere (IPCC, 2011). Scientists actively work to understand past and future climate by using observations and theoretical models. Borehole temperature profiles, ice cores, floral and faunal records, glacial and per glacial processes, stable isotope, sea level records and other sediment analyses provide a climate record that spans the geological past (Kasting& Seifert, 2002). Physically-based general circulation models are often used in theoretical approaches to match past climate data, link causes and effects and make future projections. In other words, what is observed now is compared with what was known, to determine and understand the changing trend of climate. Recent data are provided by the instrumental records, which indicate the activities that lead to climate change. The activities that lead to climate change are broadly classified into anthropogenic causes (human-activity-related) and natural causes (earth’s natural activities which are the non-human-activity-related) (see appendix F).
Anthropogenic Causes
Earth is heated up by the sun which serves as natural source of warmth thus generates the needed temperature for life forms and other activities on the planet (see appendix G). Most of the sun’s energy (heat) passes through space to reach and warm the atmosphere, earth’s surface and oceans. The rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of the earth (IPCC, 2007). In order to keep the atmosphere’s energy budget in balance, the warmed earth emits heat (energy) back to space as infrared radiation (Allison, 2009). As the energy radiates upward, most is absorbed by existing clouds and molecules of greenhouse gases in the lower atmosphere. The emitted energy goes in all directions, some back towards the surface of the earth and some upwards, where other molecules higher up absorb the energy (Allison, 2009). This process of absorption and re-emission is repeated until finally, the energy escapes to the area beyond earth’s atmosphere called space. This natural process is known as the greenhouse effect which keeps earth’s energy budget in balance. In the era leading to climate change, however, much of the energy is blocked and reflected downwards, due to increased level of GHG causing earth’s surface temperatures to become much warmer than usual (Allison, 2009). Without the abundance of the GHG, earth’s average temperature would be -19°C instead of +14°C (National Aeronautics and Space Administration, NASA, 2011). Scientists agree that the main cause of the current global warming trend is human’s increase of the GHG in the atmosphere, which blocks heat from escaping to the space (Oreskes, 2004; IPCC, 2007). Over the past centuries, the amount of GHG in the atmosphere has been relatively stable until its concentrations began to increase, due to the rising demand for energy caused by industrialization, high population, changing land use, bush burning and human settlement patterns (IPCC, 2011), which have resulted to climate change.
The earth’s climate has changed throughout history but the current warming trend is of particular significance because most of it is human-induced and occurring at an unmatched rate for the past centuries (Gabriele, 1996). In its recently released of the Fourth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded that there is more than 90% probability that human activities over the past centuries have warmed planet earth (IPCC, 2007). The report also concluded that there is a greater than 90% probability that human-produced GHG such as
CO2, methane (CH4) and nitrous oxides (NOx) have caused much of the
observed increase in earth’s temperature in the last century.
Over the last century, the burning of fossil fuels like coal and oil, and the increased level of deforestation has raised the concentration of atmospheric gases such as CO2 (IPCC, 2007). Industrial and other steam engines are also known to release CO2. The clearing of land for agriculture, industry, and other human activities have also contributed to the abundance of GHG in the atmosphere. Trees and other smaller plants replenish the atmosphere with Oxygen (O2) while utilizing the available CO2 during photosynthesis (Osinem,2005). During respiration, the trees and grasses inhale CO2 and exhales O2. This process decreases the harmful level of CO2 in the atmosphere and increases the supply of O2. The variation in the supply and utilization of CO2 affects the percentage composition of gases in the GHG layer in the atmosphere. The GHG layer primarily contains water vapor and other gases such as CO2, methane (CH4), nitrous oxides (NO2) and chlorofluorocarbons (CFCs) (IPCC, 2007). The GHG layer at normal and balanced composition of gases acts as a thermal blanket for the earth, absorbing heat and warming the surface to a life-supporting average of 59oF (15°C), (United States Global Change Research Program, USGCRP, 2009). Excess or deficient supply of any of the GHGs affects the balance of the GHG layer. The GHGs when in excess supply in the GHG layer block heat from escaping from the earth’s atmosphere into space. The excess long-lived GHGs which remain semi-permanent in the atmosphere, and do not respond physically or chemically to changes in temperature, are described as “forcing” climate change whereas gases, such as water vapour, which respond physically or chemically to changes in temperature are known as “feedbacks” (Lockwood, 2009).
Human and natural factors that can cause climate change are called ‘climate forcing’, since they push, or ‘force’ the climate to shift to new values. When ranked by their direct contribution to the greenhouse effect, the most important greenhouse gases are shown below:
Table 1
Major Greenhouse Gases
| Compound | Formula | Contribution (%) | |
| Water vapor and clouds | H2O | 36 | – 72% |
| Carbon dioxide | CO2 | 9 | – 26% |
| Methane | CH4 | 4 | – 9% |
| Ozone | O3 | 3 | – 7% |
This means that gases contributing to the greenhouse effect include: water vapor, CO2, methane (CH4), ozone (O3), nitrous oxide (NO2), and others such as halocarbons (Kiehl& Kevin, 1997). Carbon iv oxide (CO2) which is a very important component of the atmosphere, is released through natural processes such as respiration, volcanic eruptions and through human activities such as deforestation, land use changes, activities of combustion engines and burning of fossil fuels. It is reported that these activities have increased atmospheric CO2 concentration by a third (1/3) since the Industrial Revolution began (Naomi, 2004). This is one of the most important long-lived “forcing” of climate change. The seven sources of CO2 from fossil fuel combustion are (with percentage contributions from 2000 to 2004):
Table 2
Fossil Fuel Combustion
| Sources of fossil fuel combustion | Contribution (%) |
| Liquid fuels (e.g., gasoline, fuel oil) | 36% |
| Solid fuels (e.g., coal) | 35% |
| Gaseous fuels (e.g., natural gas) | 20% |
| Cement production | 3 % |
| Flaring gas industrially and at wells | < 1% |
| Non-fuel hydrocarbons | < 1% |
| International bunker fuels of transport | 4 % |
| Source: World Economics (2003). |
CO2 is relatively emitted from various fuels. One liter of gasoline, when
used as fuel, produces about 2.32 kg (about 1300 liters or 1.3 cm3) of CO2, a
greenhouse gas (Engber, 2006). Mass of CO2 emitted per quantity of energy for various fuels is show below:
| Table 3 | ||
| Voluntary Reporting of Greenhouse Gases Program | ||
| Fuel name | CO2 emitted (lbs/106 Btu) | CO2 emitted(g/106 J) |
| Natural gas | 117 | 50.30 |
| Liquefied petroleum gas | 139 | 59.76 |
| Propane | 139 | 59.76 |
| Aviation gasoline | 153 | 65.78 |
| Automobile gasoline | 156 | 67.07 |
| Kerosene | 159 | 68.36 |
| Fuel oil | 161 | 69.22 |
| Tires/tire derived fuel | 189 | 81.26 |
| Wood and wood waste | 195 | 83.83 |
| Coal (bituminous) | 205 | 88.13 |
| Coal (sub-bituminous) | 213 | 91.57 |
| Coal (lignite) | 215 | 92.43 |
| Petroleum coke | 225 | 96.73 |
| Coal (anthracite) | 227 | 97.59 |
Source: Energy Information Administration (2010).
Methane is a hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills and agriculture (especially rice cultivation), ruminant digestion and manure management associated with domestic livestock. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide, but is much less abundant in the atmosphere (Naomi, 2004).
Nitrous oxides are powerful greenhouse gases produced during soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.
Halocarbons is a family of chemicals that include chlorofluorocarbons (CFCs, which damage the ozone layer), and other human-made chemicals that contain chlorine and fluorine. CFCs are synthetic compounds of entirely industrial origin used in a number of applications, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer (Naomi, 2004). Ozone layer is a thin veil of ozone, 25 – 40 km above the earth’s surface, which protects life below from the portion of the sun’s ultraviolent radiation that otherwise damage forms of life (Osinem, 2005). The ozone veil is being damaged by chemical released on the earth’s surface, notably CFC. Each 1% reduction in ozone is likely to cause an increase of about 2% in ultraviolent rays (Osinem, 2005). Examples of the atmospheric lifetime and Global Worming Potential (GWP) for several greenhouse gases are given in the table below;
Table 4:
Atmospheric Lifetime and GWP Relative to CO2 at Different Time Horizon for Various Greenhouse Gases
| Gas name | Chemical formula | Lifetime (years) | Global warming potential (GWP) for given time horizon | ||
| 20-yr | 100-yr | 500-yr | |||
| Carbon dioxide | CO2 | About 100 | 1 | 1 | 1 |
| Methane | CH4 | 12 | 72 | 25 | 7.6 |
| Nitrous oxide | N2O | 114 | 289 | 298 | 153 |
| CFC-12 | CCl2F2 | 100 | 11 000 | 10 900 | 5 200 |
| HCFC-22 | CHClF2 | 12 | 5 160 | 1 810 | 549 |
| Tetrafluoromethane | CF4 | 50 000 | 5 210 | 7 390 | 11 200 |
| Hexafluoroethane | C2F6 | 10 000 | 8 630 | 12 200 | 18 200 |
| Sulfur hexafluoride | SF6 | 3 200 | 16 300 | 22 800 | 32 600 |
| Nitrogen trifluoride | NF3 | 740 | 12 300 | 17 200 | 20 700 |
Source: IPCC Fourth Assessment Report (2007).
Most of the GHG are extremely effective at absorbing heat escaping from the earth and keeping it trapped (Church & White, 2006). In other words, it takes only small amounts of these gases to significantly change the properties of the atmosphere. By comparison, the atmospheric GHGs that cause the earth’s natural greenhouse effect total less than 1% of the atmosphere while 99% of the dry atmosphere consists of nitrogen and oxygen, which are relatively transparent to sunlight and infrared energy, and have little effect on the flow of sunlight and heat energy through the space (NASA, 2011). A little supply of GHGs above normal has drastic effects as such small percentage caused an increase of the earth’s average surface temperature from -19°C to +14°C – a difference of about 33°C (NASA, 2011). Because the required concentration of greenhouse gases for normalcy in the atmosphere is so low, human emissions can have a significant effect. For example, human emissions of CO2 currently amount to roughly 28 billion metric tons per year (IPCC, 2011). In the next century human emissions will increase the concentration of CO2 in the atmosphere from about 0.03% currently to almost certainly 0.06% (doubling), and possibly to 0.09% (tripling) (IPCC, 2011).
Currently, CO2 in the atmosphere is the highest it has been in the past several million years (AMS, 2011). This corresponds to the increase during the transition from a glacial to an interglacial period, which under natural conditions, however, would have taken several thousand years. According to Lemke (2006);
The natural climate system has produced interglacial periods and ice ages, which caused dramatic changes, especially in the northern hemisphere. However, during the past eight ice ages, the CO2 concentration was always about 180 CO2ppmv (parts per million by volume). In the warm periods, this value increased to 280 CO2ppmv.
The duration of the transition between the CO2 minimum (180) in a glacial period and the CO2 maximum (280) in an interglacial period
took about 20,000 years. Currently we live in an interglacial period and CO2ppmv measures as high as 385, which are due to anthropogenic greenhouse gas emissions. This means that man have released to the atmosphere as much CO2 as was recorded during the transition from a glacial to interglacial period, what took 20,000 years to change, we have now realized in only 200 years.
In summary, human activities which are regarded as the anthropogenic causes of climate change include mainly, the release of CO2 and other greenhouse gases through burning of fossil fuel, gas flaring, emissions from combustion engines and other numerous industrial activities. Others include, but not limited to, deforestation and clearing of land as well as urbanization.
Natural Causes
This refers to the non-anthropogenic (non-human-related) activities that are of natural processes. Natural causes of climate change include variations in ocean currents (which can alter the distribution of heat and precipitation), orbital variation (alteration of the earth’s eccentric, angular and precession axis), solar output (variation in sun’s intensity), plate tectonics (motion resulting from deformation of rocks) and large eruptions of volcanoes, which can sporadically increase the concentration of atmospheric particles, blocking out more sunlight (NSIDC, n.d). Climate change can be attributed to variations in earth’s orbiting which alters the amount of solar energy that the earth planet receives (Lockwood, 2009). The energy from the sun is distributed around the globe by wind, ocean currents, and other mechanisms to affect the climates of different regions (Allison, 2009). Thus a change in the direction and speed of global wind and ocean currents results in a variation in the pattern of distribution of solar energy which directly alters average weather of earth, particularly in regions surrounded by water bodies.
These causative activities natural and man-induced have resulted to chemical and physical change of activities on earth, most of it is not favourable to the environment and occupants of earth; plants and animals, and there effects are visible on earth.
Ecological Effects of Climate Change
The environment can be likened to the biological system. A change in any component of a biological system will cause a distortion in the entire system. The ecological system behaves in a similar way, and climate is a fundamental element of the environment, thus any alteration in climate will consequently result to a change in the entire environment, affecting other elements of the environment. Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes are breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner (IPCC, 2007). Animal ranges refer to the confinement of species to an area or area, due to suitable survivable climatic and environmental conditions. The potential effects of global climate change include more frequent wildfires, longer periods of drought in some regions and an increase in the number, duration and intensity of tropical storms in opposite regions. Drought is a condition that results when the average rainfall for an area drops far below the normal amount for a long period of time (Osinem, 2005). Scientists predicted in the past that the effects of climate change would bring about drought, loss of sea ice, accelerated sea level rise and longer, more intense heat waves as well as increasing temperature. Increasing temperature will lead to changes in many aspects of weather, such as wind patterns, the amount and type of precipitation, types and frequency of severe weather events (IPCC, 2011). The global sea level could rise due to several factors including melting ice and glaciers. Rising sea levels could damage coastal regions through flooding and erosion. The climate of various regions could change too quickly for plant and animal species found in that region to adjust and adjust. Harsh weather conditions, such as increased heat waves and droughts, could also happen more often and more severely. Such harsh changes could have far-reaching and unpredictable environmental, social and economic consequences. Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time (IPCC, 2007). Basically, the noticeable outcomes of climate change are as follows: shrinking ice sheets, global temperature rise, acid rain, sea level rise, ocean warming and acidification, among others.
Shrinking ice sheets, declining arctic sea ice and glacial retreat are the recent happenings in the water bodies across the earth. The Greenland and Antarctic ice sheets are decreasing in mass. Greenland lost 150 to 250 cubic km3 (36 to 60 cubic miles) of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic km3 (36 cubic miles) of ice between 2002 and 2005 (NASA, 2011). Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades as well as the disappearing snow-cap of Mount Kilimanjaro, from space (Kwok &Roth rock, 2009; Polka, 2009). Glaciers are retreating almost everywhere around the world, including those in Alps, Himalayas, Andes, Rockies, Alaska and Africa attributable to rising global temperature (polka, 2009).
Global temperature has risen in recent times increasing with each decade. The ten (10) warmest years in global meteorological history occurred in the past decade, making 20th century the warmest globally in the last 600 years (NASA, 2011). Even as the 2000s witnessed a solar output decline resulting in an unusually deep solar minimum from 2007-2009, surface temperatures continued to increase causing the Greenland ice sheet and almost all mountain glaciers to melt due to warming, such as those in the Alps (IPCC, 2011). As temperature warms in different continents of the world, polar species may either move to
cooler habitats or die, altering the distribution (range) and density of animal types in a region of natural existence. Species that are particularly vulnerable include endangered species, coral reefs, and polar animals (Lemke, 2006). With 2°C of warming, dry-season precipitation is expected to decrease by 20 percent in northern Africa, southern Europe, and western Australia, and by 10 percent in the southwestern United States and Mexico, eastern South America, and northern Africa by 2100 (IPCC, 2007).Warming has also caused changes in the timing of spring events and the length of the growing season. Higher temperature causes increased rate of evaporation, leading to change in rainfall patterns and alteration of natural vegetation in various parts of the world (IPCC, 2007). Meteorological data have shown that rainfall pattern in Nigeria has changed in the past decades (Oladipo, 1995). The agricultural sector in Nigeria is highly sensitive to rainfall especially in the Niger Delta where rain-fed agriculture is mainly practiced. The Niger Delta lies predominantly in the tropics having two seasons – the wet and dry seasons. The wet season occur from May to September, while the dry season begins in October and ends in April. Rising temperature in the region has brought about uncertainty in the rainfall pattern, timing and amount (Awosika, 1995). Another problem associated with regional temperature is the modification of existing biodiversity and vegetation (Aweto, 2011). Significant loss of biodiversity is projected to occur by 2020 in some ecologically rich sites, including the Great Barrier Reef and Queensland Wet tropics (Hennessy, Fitzharris, Bates, Harvey, Howden, Hughes & Warrick, 2007). A change in the type, distribution and coverage of vegetation may occur as a result of alterations in usual regional temperature. In America by mid-century, increases in temperature and decreases in soil moisture are projected to cause savanna to gradually replace tropical forest in eastern Amazon (Magrin, Gay, Cruz, Giménez, Moreno, Nagy &Villamizar, 2007). In drier regions, climate change will likely worsen drought, leading to salinization (increased salt content) and desertification (forest and land degradation) of agricultural land. Changes in natural ecosystems will likely have detrimental effects on many organisms including migratory birds, mammals, and higher predators while habitats in terrestrial and marine ecosystems are projected to be at risk of invasive species due to changing vegetation (Anisimov, Vaughan, Callaghan, Furgal, Marchant, Prowse & Walsh, 2007). Invasion by non-native species is projected to increase with higher temperatures, particularly in mid- and high-latitude islands. The changes in vegetation will have great implication for biological productivity consequently affecting biomass production (Nduka, Orisakwe, Ezenweke, Ezenwa, Chendo, &Ezeabasil, 2008). Vegetation in regions like the Niger Delta consists of extensive mangrove forests, brackish swamp forests, and rainforests (Uyigue&Agho, 2007). The large expanses of mangrove forests in the region are estimated to cover approximately 5,000 to 8,580km2 of land (Nwilo&Olusegun, 2007). Change in vegetation in the region will lead to the impoverishment of biodiversity and the death of various plant species presently growing in the region. The regeneration rate of biomass may also decline significantly affecting the amount of fuel wood available for the local users in the region (Ndukaet al, 2008). However, destruction of vegetation has also being attributed to the occurrence of acid rain. Acid rain occurs when acid forming substances are dissolved in atmospheric water molecules and falls as rainfall with pH level much less than 7 (Osinem, 2005).
Figure 1
Linking Emitted Gases (SO2, Nox, NH3,CO2) to Soil and Water Acidification
Emissions
Acid deposition
Wet + dry
Water acidification
OUTPUTS
Aquatic biological effect
Source: Last &Whathing, 1991; Efe, 2010.
Anthropogenic activities in the past centuries have resulted in the emission of great volumes of acid forming gases into the atmosphere (Efe,2011). Some of these gases, notably Sulphur dioxide (SO2), Carbon oxides (CO2), Nitrogen oxides (NO2) and anhydrous Ammonia (NH3) from burning fossil fuels, bush burning, fumes from cars and industrial engines and other anthropogenic activities form the major source of acid deposition (Osinem, 2005). When the compounds are delivered by precipitation, such as rain and snow, the process is called wet deposition, and when they are delivered as gases, aerosols, and particles, the process is called dry deposition. In addition, in high-elevation and coastal regions, they may be delivered through cloud or fog water, called cloud deposition (Efe, 2011). The concept of acid rain was first discussed by Robert Augus (1872) during the industrial revolution to mean any acidic precipitation (such as rain and fog among others) or depositions that occur downwards in areas where major emission of SO2, CO2, and NO2 takes place (Oden, 1976). Acid deposition can occur via natural sources like volcanoes but it is mainly caused by the release of sulfur dioxide and nitrogen oxide during fossil fuel combustion from man’s activities. When these gases are discharged into the atmosphere they react with the water, oxygen, and other gases already present there to form sulfuric acid, ammonium nitrate, and nitric acid. These acids are dispersed over large areas corresponding to wind patterns and fall back to the ground as acid rain or other forms of precipitation. Acid rain affects both natural and man-made environments (Mama &Osinem, 2007). Aquatic settings are the most impacted by acid rainfall as acidic precipitation falls directly into them while dry and wet deposition also runs off of forests, fields, and roads and flow into lakes, rivers, and streams (Amanda, 2013). The author further stated that as the acidic liquids flow into larger water bodies, it is diluted, but can accrue and lower the overall