Acid rain is a known consequence of planetary heating, which has damaged many aquatic environments and aquatic workss throughout the universe. This survey investigates the effects of acerb rain on an aquatic works ‘s rate of photosynthesis. The research inquiry is “ How does the alteration in pH of an Elodea ‘s home ground due to acid rain affect the works ‘s rate of photosynthesis? ” Samples of Elodea were placed into two acidic solutions, 0.01 Molar solution of azotic acid and 0.001 Molar solution of azotic acid, in a photosynthometer.

The control group is H2O in the photosynthometer with a pH of 7. Each test took 24 hours and the experiment was done in a high school chemical science lab near a window shelf, off from direct sunshine. After each 24 hr period, the sum of O released by the workss is measured to find the rate of photosynthesis.As the environment becomes more acidic, the Elodea samples ‘ volume of O release decreases. The mean volume of O release for the Elodea samples in the control H2O group is 0.57 milliliter, 0.29 milliliter for the pH 4.

0 group, and 0.15 for the pH 3.5 group. The consequences from this survey suggest that there are large differences among the three groups and that acid rain negatively affects the rate of photosynthesis.

1.0 Introduction1.1 Rationale of StudyPresents, planetary heating has become a large issue on the head of environmental jobs. It ‘s non merely the desolation of lifting temperatures all over the universe but other effects as good which can be much more unsafe and harmful to the human race.

One of these effects is the addition in the sourness of precipitation, or acid rain. At present, acerb rain affects big parts of the United States and is particularly noticeable near big metropoliss. The one-year sourness value norms at pH 4 but values every bit low as pH 2.1 have been observed. It is confirmed that the increased usage of natural gas and development of mills have been associated with the increasing sourness of precipitation and therefore, attempts had been made to trust on more clean, renewable energy beginnings and the development of air quality emanation criterions. However, non all the economic and ecological effects due to the debut of strong acids into the natural systems are known and hence, this survey looks into one of its many harmful effects, the acidification of fresh water ecosystems.Surveies suggest that no affair how little the alteration in pH of any aquatic ecosystem is, big sums of Mg and Ca would still be lost in the locality affected by acerb rain.

As a consequence of the loss of these critical elements, the response and recovery of any aquatic ecosystem toward the lessening in acerb deposition would be delayed significantly. Because of this, any farther decrease in pH of the ecosystem will convey approximately exponential additions in harm to any life being within the affected country. Just like how harm to the human immune system would take to important, exponentially increasing harm to the human organic structure in the signifier of diseases, the harm done to the recovery mechanisms of an aquatic ecosystem due to acid rain opens up possibilities for calamities that could be of a far worse magnitude.One such possible catastrophe is the harming of aquatic workss ‘ rates of photosynthesis. Alongside the hazard of the population of crustaceans, insects, and angle within the aquatic ecosystem, the harm done to the aquatic workss ‘ rates of photosynthesis such as Elodea Canadensis ‘s, can be one of the worst possible effects of acid rain and planetary heating. This survey is worthwhile in that workss are the footing of the nutrient concatenation and any harm inflicted upon the procedure of photosynthesis in general would certainly intend that our really ain being is in hazard.

1.2 AimThe purpose of this paper is to analyze the effects of the alteration in pH of Elodea Canadensis ‘s environment on the works ‘s rate of photosynthesis. In a broader context, this survey investigates the effects of acerb rain on aquatic workss.Hence, the research inquiry is: How does the alteration in pH of an Elodea ‘s fresh water home ground due to acid rain affect the works ‘s rate of photosynthesis?The rate of photosynthesis is measured with a photosynthometer in which O released from the Elodea samples are collected under differing pH environments.

The Elodea samples are placed in differing solutions of azotic acid, which are used to imitate Elodea life in freshwater home grounds affected by acerb rain. Because O is a merchandise of photosynthesis and is correlated to the rate of photosynthesis, O is so collected from the assorted experimental groups. Most experiments that require the measuring of the rate of photosynthesis of a macrophyte determine the alterations in O concentration of the system in which the macrophyte is kept in and therefore, this survey is done in the most popular mode. The volume of O collected from each group would so be analyzed to find the optimum conditions for an aquatic works to populate in and the effects of acerb rain on the rate of photosynthesis.1.3 Acid RainBecause the value for uncontaminated precipitation is officially set at pH 5.65, the same value as distilled H2O, acid rain is a term that describes rain with a pH of less than 5.

6. Man-made emanations of S and N pollutants had ever been blamed as a major cause of acerb rain but a echt cause-effect relationship has ne’er been determined. However, it is certain that S and N compounds react with the ambiance to bring forth acids that would take down the pH of precipitation. There are besides many natural beginnings of these Ss and nitrogen compounds. For illustration, about 50 per centum of atmospheric N compounds are produced by lightning discharges, which may convey about acerb rain.The existent importance of analyzing acerb rain though is to analyze its effects on the natural ecosystems.

One such ecosystem that is affected greatly by acerb rain is the aquatic ecosystem. The chemical composing of lakes is to a great extent influenced by precipitation and many surveies have suggested that acid rain has caused lake acidification. Most significantly, the alterations in pH of these ecosystems due to acid rain appeared to hold damaged aquatic workss ‘ metamorphosis, doing a diminution in primary productiveness. Because these aquatic works communities are primary manufacturers, any harm done to their metamorphosis mechanisms ( photosynthesis ) can drastically cut down the nutrient supply and energy flow within the affected ecosystem. Therefore, acerb rain has the possible to cut down the supply of minerals and foods and jeopardize the being of all beings within an ecosystem, particularly aquatic ecosystems.1.4 Marine PhotosynthesisThe metamorphosis of workss is normally referred to as photosynthesis.

Photosynthesis involves two sorts of procedures, photochemical and enzymatical, intending that the rate of photosynthesis is a map of irradiance and enzyme activity. No enzymes are involved in the photochemical procedure in which the works absorbs visible radiation in the scope of 350 and 700 nanometer in wavelength. In this procedure, chlorophyll molecules absorb light and excites negatrons, which go through the negatron conveyance and stop up bring forthing ATP and NADPH. As its name implies, the photochemical procedure involves light and is strictly chemical science.The other procedure is the light-independent enzymatical procedure of the Calvin rhythm. This procedure occurs after the light-dependent reaction for it requires the ATP and NADPH to cut down CO2 to carbohydrate. At the start of this procedure, six C dioxide molecules attach to six 5-carbon ribulose biphosphate ( RuBP ) molecules to make six molecules of a 6-carbon compound.

Each of these 6-carbon compounds splits into two 3-carbon molecules called phosphoglycerate ( PGA ) . This consequences in 12 PGA molecules. Energy from ATP and negatrons from NADPH are so needed to cut down each of these PGA molecules into 12 G3P ( glyceraldehyde 3-phosphate ) molecules. Finally, two of these G3P molecules are used to organize one glucose molecule and the staying 10 G3P are reassembled into RuBP molecules.Marine Photosynthesis besides requires CO2 to get down and this CO2 is acquired when CO2 is dissolved in H2O. This procedure is represented by the undermentioned expression:CO2 + H2O ?a H2CO3CO2 + OH- ?a HCO3-The dissolved CO2 in the H2O can either do the H2O addition or lessening in pH depending on the pH, temperature, and salt of the environment. The concentrations of carbonaceous acid ( H2CO3 ) and hydrogen carbonate ( HCO3- ) in the aquatic environment signifier a complex equilibrium, which is needed to prolong optimum life conditions for its dwellers ; the two compounds play a critical biochemical function in the pH buffering system, which strongly affects photosynthetic beings.1.

5 Elodea CanadensisElodea Canadensis is an aquatic vascular works that spends its full life rhythm under the surface of a organic structure of H2O. It is a perennial with a flexible subdivisions root and hempen roots. Its foliages do non hold leafstalks and they are ever in groups of three to seven spread out equally along the full length of the root. The species of Elodea Canadensis is normally known as waterweed and is abundant in North and South America. However, there are 17 species of the genus Elodea and these workss are common throughout the universe with usage as an fish tank works. Its usage in scientific discipline experiments is reasonably common as good due to its strongly photosynthetic, heavy chloroplast construction.

When exposed to a strong visible radiation beginning, the O bubbles given off by the works is clearly seeable. Another ground for its usage in scientific discipline experiments is that it is able to populate plenty after being cut into smaller strands to be experimented on.2.0 Variables2.1 Independent VariableThe Elodea workss are placed in 2 different azotic acerb solutions of changing pH and molar concentration.

Strands of Elodea with 10 foliages each are subjected to either a 0.001 molar solution of azotic acid with a pH of 4.0 or a.01 molar solution of azotic acid with a pH of 3.5. The solution and Elodea are placed into the barrel of the syringe in the photosynthometer. Litmus paper is used to mensurate the pH of the acerb solutions.2.

2 Dependent VariableThe rate of photosynthesis of the Elodea samples are affected by the changing pH of the solutions they are subjected to. The rate of photosynthesis is indicated by the volume of O given off by each 10 foliage Elodea strand and collected in the photosynthometer over a 24 hr experiment period.2.3 Control VariableThe control variable is tap H2O with a pH of 7.0, a impersonal solution, in the photosynthometer. It is used to find whether or non the acidic solutions the Elodea strands are tested in really have an consequence on the workss ‘ rates of photosynthesis as compared to a impersonal aquatic environment.2.4 ConstantsAll tests are done in the same chemical science research lab following to a window shelf, off from direct sunshine.

The room and the solutions inside the syringe of the photosynthometer are kept at a changeless 26.4A° Celsius. Each Elodea sample is a 10 foliage strand. The same volume of solution is used for every test in the photosynthometer.

3.0 Procedures3.1 Preparation before experimentation3.1.1 Test TestsBefore any definite process of experimentation is made, trial tests needed to be done foremost in order to see which acerb solutions would non kill Elodea in a 24 hr period. Strands of Elodea are placed in trial tubings with 0.

001 grinder, 0.01 grinder, and 0.1 molar azotic acid solutions and are labeled. By the terminal of the 24 hr period, the Elodea in the trial tubing with the 0.

1 molar azotic acid solution died since the foliages lost all of their green colour and O bubbles were non released from the foliages even before the 24 hr period. This meant that the works could non execute photosynthesis any longer and was dead. The other two elodea samples were alive and therefore, the 0.001 grinder and 0.

01 molar azotic acid solutions were used for experimentation to mime the consequence of acid rain on an aquatic works ‘s rate of photosynthesis.3.1.2 Nitric Acid Solutions PreparationThe 0.01 Molar solution of azotic acid is made by blending 1 milliliter of a 1.0 Molar solution of azotic acid with 99 milliliters of tap H2O in a calibrated cylinder. The tap H2O is measured with the calibrated cylinder and a pipette is used to keep 1 milliliter of the 1.0 Molar solution of azotic acid.

1 Liter of a 0.001 Molar solution of azotic acid is prepared by blending 1 milliliter of a 1.0 Molar solution of azotic acid with 999 milliliters of tap H2O in a litre plastic research lab bottle. 1 Liter of this solution is made since it is more convenient to make a big volume of an acerb solution with a low concentration than it is to make a little volume of a extremely diluted acerb solution.3.1.3 Apparatus PreparationThe photosynthometer is assembled by linking a syringe to a graduated 1-cm3 pipette with a short length of gum elastic tube.

The length of the gum elastic tube is arbitrary every bit long as it is tight plenty to procure the syringe to the pipette, forestalling any liquid from coming out of either the syringe or pipette.The setup is fixed in a perpendicular place with the trial tubing clinch and ring base ( Figure 1 ) , utilizing the trial tubing clinch on the syringe and linking that to the ring base.3.2 Method for Experimentation with the Photosynthometer3.2.1 Application of Elodea Sample and Solutions into the PhotosynthometerBefore experimentation, a sample of Elodea is taken by cutting a strand of Elodea with 10 foliages. The mass of the Elodea is recorded and measured in order to look for forms after experimentation. The speculator of the syringe is so removed and the elodea sample is placed into the barrel of the syringe.

Since any liquid placed in the syringe with the speculator off will fall directly through and out the setup, the Elodea sample is placed in the setup foremost before anything. 30 milliliter of the 0.001 Molar solution of azotic acid is so poured into the barrel of the syringe and the barrel is instantly sealed with the speculator to forestall any more liquid from go forthing the setup. No affair what, some of the solution would still go forth the setup with the speculator off. Therefore, 30 milliliter of the solution is used in the barrel so that any extra sum of the azotic acid solution could be expelled by forcing down on the speculator until 15 milliliters of the solution is left in the barrel of the syringe. With the setup removed from the trial tubing clinch and the unfastened terminal of the pippette pointing upwards, any at bay air inside the syringe and pipette is expelled by easy and softyly forcing the speculator into the barrel until all of the at bay air expelled, doing certain non to hold any of the solution leave the pipette.3.

2.2 Keeping ConstantsWhen the setup is placed back onto the trial tubing clinch and ring base, the temperature of the azotic acid solution inside the barrel of the syringe is measured with an infrared thermometer and recorded. The temperature is measured to do certain that the temperature remains changeless for all tests since temperature does impact the rate of photosynthesis. To keep changeless temperatures and conditions conditions as good, experimentation is done in one room for all tests and Begins at the same clip of twenty-four hours. In my instance, experimentation was done in the school ‘s chemical science research lab, which was kept at a changeless 26.4A° Celsius, at 16:00 US cardinal clip.3.

2.3 Data CollectionThe volume ( the location of the semilunar cartilage ) of the azotic acerb solution in the pipette of the setup is measured and recorded. The clip is measured and recorded every bit good. The elodea sample is left in the setup for 24 hours. After that clip, the sum of O the sample of Elodeas gave off is measured and recorded by looking at the location of the semilunar cartilage of the acerb solution in the pipette.

All experimental processs are so repeated with the 0.01 Molar azotic acid solution and tap H2O alternatively of the 0.001 Molar azotic acerb solution.

Figure 1: Photosynthometer Apparatus4.0 Data Collection4.1 Raw Data: Volume of Oxygen given off by Elodea in Different pH Environments


Volume of Oxygen Released ( milliliter )

Trial 1

Trial 2

Trial 3

Trial 4











11A±.01.20A±.01.12A±.01Table 14.2 Raw Data: Mass of each Elodea Sample


Mass of Elodea Sample ( g )

Trial 1

Trial 2

Trial 3

Trial 4











352A±.001.286A±.001Table 24.

3 Data Processing: Comparing Mean Volume of Oxygen Release of ElodeaGraph 14.4 Data Processing: Trendline for Mean Volume of Oxygen Release VS. pH of EnvironmentGraph 24.

5 Data Processing: Comparing Percent Difference of the Average Volumes of Oxygen Release of the Experimental Groups to the Control Group ‘s Average Volume of Oxygen Release


Percentage Difference

4.049 %3.574 %Table 34.6 Data Processing: Comparing Standard Deviations of Volume of Oxygen Release of Elodea


Standard Deviations


1104.0.0253.5.05Table 44.7 ANOVA trialThe ANOVA ( Analysis of Variance ) trial is besides used to further verify the difference of the consequences among the experimental groups. The consequence of this ANOVA trial indicates whether the experimental variable ( pH of the Elodea ‘s environment ) causes important difference on the Elodea ‘ rates of photosynthesis.Before the ANOVA trial could be carried out, three premises are made:Observations are independent ( the value of one observation is non correlated with the value of another observation ) .

Observations in each group are usually distributed.Homogeneity of discrepancies ( the discrepancy of each group is equal to the discrepancy of any other group ) .The void hypothesis of this trial is: there is no difference between the agencies of the different groups ( pH 7.0, 4.0, and 3.5 ) . Then, the statistic trial is carried out to happen the F ratio.F Ratio = Mean square between groupsMean square within groupsIf the computed F ratio is greater than the F critical value at the significance degree of 0.

05, the void hypothesis is rejected.


F Ratio

F Critical Value ( 5 % )


7.0 vs. 4.045.845.057Significant Difference7.

0 vs. 3.56360.411Significant Difference4.0 vs. 3.521.

531.360No Significant DifferenceTable 55.0 DecisionGraph 1 shows that the average volumes of O release among all the groups had important differences.

The mean volume of O release for the pH 4.0 group is 0.29 milliliter, which is about half of the average volume of oygen release for the control group, pH 7.0, of 0.57 milliliter. The average volume of O release for the pH 3.

5 group is 0.15 which is about half of the average volume of O release of the pH 4.0 group every bit good. As shown in Graph 2, this tendency is shown to be of an exponential diminution in average volume of O release as pH additions ; as the environment becomes more acidic, the average volume of O release declines more aggressively. Harmonizing to Table 3, the mean volume of O release of the pH 4.

0 group differs from the control pH 7.0 group by 49 % . The mean volume of O release for the pH 3.5 group differs from the control pH 7.0 group by 74 % . These values are big and once more stress the important difference of the consequences of the experimental groups to those of the control group. Harmonizing to Table 5, ANOVA trial consequences, there is a important difference between the average volumes of O release between the pH 7.0 and pH 4.

0 groups, every bit good as the pH 7.0 and pH 4.0 groups. However, there is no important difference between the consequences of the pH 4.0 and pH 3.5 groups.

From the ANOVA trial consequences, the hypothesis that the Elodea ‘s rate of photosynthesis would be harmed in more acidic environments is supported. A alteration from an environment of pH 7.0 to pH 4.

0 would greatly cut down an Elodea works ‘s rate of photosynthesis while a alteration from an environment of pH 4.0 to pH 3.5 would non convey about a important decrease in an Elodea works ‘s rate of photosynthesis. The standard devation values from table 4 province on mean how far the information varies from the mean. For each group, the standard devation is comparatively low comparedto the norms of each test and therefore, the informations collected and the methods used to roll up the information is really precise.Increasing the sourness of an environment consequences in a figure of physical, chemical, and biological alterations.

A chemical alteration that could happen is the alteration in the handiness of C. With the pH of the environment at somewhat acidic degrees, the sum of dissolved HCO3- in the H2O bead. This dissolved HCO3- in the H2O is the workss ‘ beginning of C used for photosynthesis and it is proven that aquatic workss have the best rate of photosynthesis in somewhat alkalic environments due to the handiness of C in the dissolved HCO3- .

The lower pH degrees in the environment besides affect the enzymes in the cells of the works. If pH degrees bead low plenty, enzymes such as RuBP used in the Calvin Cycle would close off and would no longer transport out the chemical reactions needed for photosynthesis. Not merely would the acid in the environment kill the enzymes but the acid would besides destruct the works proteins, lipoids, and membranes, doing works cells to malfunction and a major decrease in the rate of photosynthesis. Specifically, the lowered pH of the environment causes changes in the chlorophyll molecules, which are extremely indispensable to the procedure of photosynthesis.

6.0 Evaluation and SuggestionsPossible random mistakes include the inaccuracy of the solution molar concentration stated, mass stated, and volume of O release stated. These random mistakes may be caused by the inaccuracy of the measurement equipment. The equipment such as calibrated cylinders and pipettes are reasonably accurate though to an extent.One possible systematic mistake could be the different multitudes of each Elodea sample. The mass of each strand may impact the volume of O released for mass may find the sum of chloroplast in each sample.

Since each Elodea sample was cut from a larger strand, this film editing may besides cut each sample ‘s life. With a sample ‘s life cut short, the volume of O collected from this experimentation may non truly reflect how workss move outside of these laboratory conditions. Besides, the worst beginning of mistake in mensurating the rate of photosynthesis with a gas aggregation method may be the gas storage within the foliages.

If some O is stored in the foliages, the O collected in the photosynthometer may non to the full represent the samples ‘ true rates of photosynthesis in the tried environments.Some steps that could be taken to forestall these mistakes could be to utilize more accurate equipment and utilizing works samples of similar mass every bit good as figure of foliages.Entire Word Count: 3,002

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