In recent times, there has been an increase in awareness as regards to the meaning and the effects of air pollution on our environment. This might be as a result of education and peoples perception of their health need. Air pollution comes in different forms and it affects humans, animals and plants in varying degree. An important form of air pollution in our environment is the acid rain. This form of air pollution is now a serious environmental issue in developed countries of world especially in Europe (Likens, Driscoll  Buso 1996). Acid rain is a term that has been used to describe a form of air pollution in which airborne substances which are produced from industrial waste or electric utility plants are released into the atmosphere. These substances undergo chemical changes and result into the formation of acidic compounds. Acid rain also denotes deposition of acidic compounds into rain, snow and fog hence could be referred to as a form of precipitation (acid precipitation).
Acidic substances are found to be widely distributed in nature. They are found in our stomach, and in fruits such as grape and vinegars. They can also be produce in the laboratory by chemical reactions. Base which when mixed with acid neutralizes the effects of the acid also occur in diverse forms. It can be produce synthetically in form of ammonia or occur as a form which is found as a constituent of pancreatic juice in humans. Some medication such as antacid also contains bases.
Proper understanding of the acid such as it common sources in the environment and how its being measured are essential to the assessment of its impacts on our environment. Acids describe corrosive property of a substance and a substance is said to be acidic if it can release hydrogen ion to form a solution. Such substance acidity could only be assessed by its pH value. PH is a scale that is used to determine the acidity or alkalinity of a substance and it range from 1-14 with a neutral point being placed at 7. Any substance or compound greater than 7 is said to be basic in nature while those less than 7 are said to be acidic in nature.
The term acid rain has been used to describe a rain with a pH value below 5.6 and has been found to be much more common in highly industrialized communities. The main contributing compounds to this form of air pollution are oxides of sulphur and nitrogen which are released into the atmosphere and then get converted into substance such as sulphates and nitrates which in turn yield sulphuric acid and nitric acid in the presence of moisture. Substances that are released into the air are the main contributor to acid rain. These substances which are oxides of sulphur and nitrogen are majorly from exhaust fumes of vehicles, industrial plants and power generators. Increase in human use of all these forms of machines can be attributed to increase release of fumes or all the poisonous gases into the atmosphere and hence increasing the level of formation of acidic compounds in the rain.
Apart from industrial release of these poisonous substances, minor amount can also be contributed by burning of fossil fuels and various forms of agricultural activities. All these sources go a long way in contributing to the increase incidence of acid rain in various communities. Nature has a way of maintaining a state of equilibrium. This can be seen in our environment in the sense that some naturally occurring bases found in the air and soil or those release to the air probably as a result of decay of dead animal have a way of neutralizing the corrosive nature of acid that has been released into the atmosphere or those found in the biosphere.
As was stated in the introductory paragraph, the increase in awareness as regards to deleterious effects of this form of air pollution, has led to formation of several policies and strategies against release of substance that lead to acid rain by government so as to reduce the level of acid rain hence reducing it effect. Through good policies and strategy when formulated and properly implemented it can actually help reduce the effects of acid rain.
Acid rain has several negative effects on plants, animals, soil, surface water and other human made structures. The effect of acid rain on soil is usually attributed to the dissolution of the important soil nutrient and washing them away hence slowing down their growth (Johnson, Driscoll  Eaton 1981). It has been associated with a diminishing fish population and malformation hence causing a potential human effect. This has strongly influence the perception that there are both indirect and direct effects of acid rain on human population.
Analysis of the effect on acid on fresh water ecosystems have shown that acid vulnerable regions are much more numerous and widespread contradicting what was believed in few years back. In this analysis, lakes and streams were found to be more vulnerable to acidification by the effects of acid rain and this are in the region of North America where their lakes have lost the ability to neutralize the acid hence resulting in increase rate of biological damage. Many invertebrates were found to be very sensitive to all these changes with host of them disappearing at acidic pH low as 6.0. Some areas have also shown a decrease in the rate of acidification attributed to consequence of acid rain are on the decline, this was attributed to a recent decreases in sulfur oxide emission (Schindler 1988).
There is high level of acid rain in the United States with the average annual pH of 4.05-4.3 where the contribution of sulphuric acid has been found to account for about 55-75 percent of measurable acidity. Clean Air Act which was passed in 1990 made an impact in the reduction of sulphur dioxide being released from the school. However, this has not significantly precluded forest and aquatic ecosystems so as for such habitat to recover from the effects of sulphuric acid (Likens, Driscoll  Buso 1996).
    The introduction of the Clean Air Act of 1990 has been attributed to current reduction of acid rain being experienced in certain parts of United States especially the Eastern States. This region of the country has long being recognized has the region with highest occurrence of acid rain the united states and the pollutant founds to largely contributes to this form of air pollution are those from local sources and sources located from the Midwest. Out of all the implicated sources of acid rain, 30 percent nitrogen oxides are released from the power generating plants, 30 percents are attributed to those released from automobiles while additional 25-30 percent are from agricultural sectors. Other minor sources are those nitrogen oxides that are released from the process of lightening and other biological process. (Penn State 1998).
The concentration of sulphate ion that are found to be implicated in acid rain was also found to be on the decline in the Eastern part of United states from the period of 1995 through 1997 as compared those analysis done before that period. This shows that there is actual reduction in the level of acid rain in that community but the concentration of nitrate ion which also contribute to acid rain were found not be on the decline hence showing that the clean air act of 1990 that was formulate to reduce acid rain occurrence were limited in it effectiveness in that it only help reduce those emission associated with the release of sulphur dioxide (Lynch, Bowersox  Grimm 2000).
Acid rain leads to various forms of destruction affecting both the living and non living things. This is because it is corrosive to metal, stones and paints which are non living things while it is poisonous to living things ranging from aquatic organisms to terrestrial ones. It affects the growth of plants, cause damages to leaves hence reducing yield. It effects on the plants can be measured in the laboratory by simulating the acid rain. This is usually done by conducting an experiment that allows the scientist to grow certain plant in a controlled group and experimental group simultaneously. Effects of acid can then be measure when the scientist ensures that all other variables are made constant for both the control and the experimental group. Features of plant growth can then be evaluated after certain period of time.
    Since acid rain has been found to be directly destructive to both plant structure and indirectly destructive to the growth, it effects on the growth and leaves of the sunflower will be evaluated in the experiment. Two hypotheses were tested
1) Ho there is no observable difference in the growth of sunflower samples obtained from a control environment when compared to samples grown from the experimental environment.
2) Ha there is an observable difference in the most probable number of fronds in samples obtained from a control environment when compared to samples taken from the experimental environment.
The Null Hypothesis will be tested.
Method and materials
2 peat cup
Plant seed
pH meter
Ruler or tape rule
Cup of vinegar
Two peat cups were collected (one for the control and the other for experimental group. Each cup was filled with potting soil and a hole of 4 cm deep was made in the soil. Three sunflower seed were placed in each hole that has been created in the soil and the seed were then covered with soil. The two cups were watered until the seedlings started sprouting. In the control group, 50 ml of water is used to water the seed. In the experimental group, 50ml of a mixture of vinegar and water was used to add water to the seedlings in the experimental group. The two cups that has been watered were then place at an indoor location.
 The two pots after placement at the indoor location were then left for some weeks so as to assess the growth. The heights of the plant, the total number of leaves and the pH of the soil in each cup were measured at least three times a week. Subsequently, 20 ml of water are being added to control group everyday while the same volume but made up of mixture of vinegar and water is used to water the experimental group. This process of watering the two groups was then continued for the period of four weeks so as to be able to evaluate the effect of lowered pH on the growth of the seed.
It is also very important to note that while the experiment was being conducted, all other variable apart from those of important to the experiment were made to be constant. Variables such as the size of the cup, the amount of time for the experiment, the nature and amount of soil, the volume of liquid and the amount of seed that could directly or indirectly influence the growth of the plant were ensured to be constant.
ControlDateHeight of LeavespHSignature111720093cm26111920098.526112020099.926Ming Lin112520091336Prof. Wildt1129200916.636Ryan Moran113020091746Qian Gu1201200917.54.56Ryan MoranExperimentDateHeight of LeavespHSignature111720092.5cm26111920096.25cm26112020097.5cm26.5Ming Lin1125200910cm25.5Prof. Wildt1129200910.5cm25Ryan Moran1130200911cm24Qian Gu1201200915.5cm34Ryan MoranConclusion
In this experiment, the result shows that at constant pH, there is a constant growth of the sunflower in terms of height and number of leaves. When the measurement were left for certain number of days without measurement (that is about 5 days) appreciable growth in terms of height were noticed showing that the sunflower is growing at a specific rate. In the experiment group, the height of the sunflower was comparably less when compared to that of controlled group at the same pH. This might have been a result of lowered amount of water since the volume of water in this case is about half of that used in the controlled group. When the pH was increased, there is no significant improvement in growth when compared to the controlled group. When the pH of the soil fell below 5.5, the noticeable or significant impairment seen is in the number of leaves which was found not to increase when compared with the controlled group with the a constant pH. These changes help reject the null hypothesis which indicate that there is no observable difference in the growth of sunflower samples obtained from a control environment when compared to samples grown from the experimental environment hence supporting the main hypothesis. This results shows that lowered pH had an impact on the growth of sunflower in terms of number of leaves and the height of the plant.
     The question that needed to be reviewed or subjected to further research is that why is it that when the pH of the experimental group was slightly increased, there is no appreciable changes. Another major factor that needed to be considered was the type of acid in the vinegar that was used. It might be other forms of acid that has little effects on the growth of sunflower. The initial pH of the soil was not also analyzed and this might have had some effects such as neutralization of the acid added to the soil. Because a soil with high alkalinity will show tendency of neutralization of any form acid added to the soil.
My recommendations are that the government should formulate new strategies and Acts that will help reduce the release of emission especially those associated with oxides of nitrogen so as to reduce the impact of acid rain in our environment.


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