Background Information

Elodea plants are able to get carbon dioxide underwater because they have thin and edgy leaves that increase the flow of carbon dioxide. The leaves are surrounded by thin porous cuticles, where carbon dioxide enters the plant. When a plant cell is submerged in water, fluid will enter the cell via osmosis until the osmotic potential is balanced by the cell wall's resistance to expansion. The plant will become rigid and submerged because of the water gained by osmosis. Turgor pressure develops against the cell wall after water enters the cell's vacuole. If an Elodea plant is placed into basic water, then the cells will swell up, and the plant will become more rigid. Elodea plants take out the acidity from the water and produce oxygen.

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  Plant Life Underwater started with the very simple idea of life underwater. Each member of our group wanted to try a simple project that included life underwater. Elodie wanted to work with plants or animals, and Charlotte wanted to work with different substances underwater. Then Devon decided she also wanted to experiment with plants, and Sabrina had studied the ocean in sixth grade. She wrote a report on life in the deep ocean. She was very excited that people were going to create a project on underwater plants. Thus our project formed. At first, we thought about guppies, but then we decided that what we wanted to do wouldn’t work with guppies. We wanted to test the limits of life in water. So we started with a broad idea. At first, our group experimented with succulents, wondering if they could survive underwater and if different depths affected the plants at all. Our group had begun thinking about plants and how certain plants managed to adapt and survive through tough underwater circumstances. However, we realized that succulents wouldn’t be adequate. Our plan evolved into using the elodea, which is a very hardy plant that can live through extreme conditions. Realizing how difficult bringing a plant down to certain depths was, we decided to adjust our project to discuss different substances in the water. We introduced liquids like shampoo, conditioner, and lemon juice and began experimenting.

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Our group studied and researched aquatic plants. In order to learn more about ecology, we had to study photosynthesis and the various adaptations of underwater plants. After extensive research, we wondered how much acidity an elodea plant could tolerate before it dies. We were also curious as to how the cellular structure of the plant would change based on different underwater circumstances. After researching more about acidity, pH, and aquatic plants, we finally came up with a hypothesis. We hypothesized that a piece of elodea fully submerged in slightly acidic water will act as a water purifier and increase the overall pH. 

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Our hypothesis was correct. Placing the elodea plant in acidic water for a day increased the pH level by 0.1. Our hypothesis described the process of our experiment, which was placing the elodea in acidic water. The acidity came from the lemon juice we put in the test tubes. We also put shampoo and conditioner in the water, which made the water alkaline. We thought that the plant would act as a natural water purifier, and the acidic water would gradually become less acidic. The elodea absorbs carbon dioxide, producing oxygen. The plant's health depends on the acidity of the water.

 The cellular structure of the elodea plant is dependent on the levels of underwater pressures and circumstances. We predicted that when an actively photosynthesizing elodea plant is fully submerged in highly acidic water, it will act as a water purifier and take the acidity out of the water, causing the pH to be more basic. The elodea plant increased the pH levels of any water it was submerged in. Therefore if the acidic levels of the water are high, in other words, the water is basic, the cells of the elodea will become sturdier and have a better chance of survival. By taking the carbon dioxide out of the water, which decreased the amount of carbonic acid, the water eventually became slightly basic such as a pH above 7. Placing the elodea in Basic water/nonacidic, it caused water movement into the cell resulting in swelling of the cells. We hypothesized that the outward pressure of the water promotes the rigidity of the cell, and the plasma membranes are pushed against the cell walls of the cellular structure.

Results

After collecting the Elodea from the test tubes, we meticulously observed them under the microscope. The pH of the water went up by 0.1 pH point per day. These results prove that the elodea filters acidity from the water and, over time, increases the overall pH. Unfortunately, after a week of exposure to open air, the water started molding. This skewed our pH levels and changed the overall result. The moldy flasks’ pH went down, while the nonmoldy flasks’ pH levels increased.

Error & Analysis

While our experiment was successful, we had one major issue that may have skewed the results. The elodea had been filtering the acidity out of the water, so the pH was expected to increase over time. The pH was steadily increasing by 0.1 every day, but, unfortunately, some of our test tubes grew mold. We think the mold in the tubes grew because the test tubes were openly exposed to the air for a long period of time. In the future, we should try to work on making sure the test tubes are fully covered. We should also use a test tube stopper to block the airways, which will prevent mold issues in the future. Through this error, we discovered that the moldy test tubes had a lower pH than they started with. 

Connections

The acidity of freshwater has increased by 0.3 pH units in the last 35 years. Fresh water has become more acidic ten times faster than the ocean, in which the acidity has increased by 0.1 pH unit in the last 100 years. The pH scale is logarithmic, so the effects on the water are exponential in real terms. Needless to say, the acid levels in freshwater are increasing due to sulfur oxides and nitrogen coming into the water through the atmospheric gasses. In our experiment, we filled beakers with fresh water and then added lemon for acidity. After measuring the acidity of each beaker with pH sticks, we placed elodea in the beakers and left it there for a day. We discovered that the elodea plant actually decreases the acidity level of the water. We found that after a day, the acidity decreased by 0.1 pH point. 

Our results prove that by placing elodea plants underwater, we can decrease the acidity of fresh water and make it more drinkable not only for us but also for the animals that rely on this as their source of water. Every day animals are dying due to dehydration. This is a worldwide problem. Over five million people die each year due to drinking acidic water. These elodea plants could save millions of lives. If we implement this natural water filter, we could save millions of people and animals. If we don’t take immediate action, then the problem will become worse and cause societal decline. 

If we let this go on for just 50 years, we could be looking at a scarcity of resources vital to human survival, such as fresh water and food. If animals continue to die from drinking this water, then we could be looking at a world with no meat. If we let this problem go unnoticed, it will become worse and could potentially wipe out the human race. By using the elodea to make acidic water more drinkable, we could prevent massive extinctions and save our society. Our leaders should plant more elodea and create programs that encourage people to plant and use the elodea to extract acidity from fresh water. Our leaders should also create programs that distribute elodea into freshwater banks in our forests. If enough people contribute to the programs, we could be looking at an abundance of resources such as fresh water and meat.