Introduction
In our experiment, we are testing to see how different plant species are affected by different amounts of salt water. We will have two freshwater plants and two saltwater plants. One of each species will be placed in water containing its natural salt level. These will serve as our base experiment. The freshwater plant will be placed in a flask containing high amounts of saline water. The saltwater plant will be placed in a flask containing lower to no amount of salinity than its natural level. We will track the growth of each plant and take pictures to observe if the color of the plant changes. Our group was drawn into this experiment because it incorporates global warming and plants into one project. We wanted to see how global warming can affect plants living in the ocean. We were both interested in how humans will be affected by global warming and all life on Earth.
Problems
Our experiment is showing how global warming will affect plants living in the ocean or on the coastline. As glaciers melt there will be an increase of freshwater entering the ocean. Therefore, our experiment mimics the global warming issue when we add freshwater to our saltwater plant. As more freshwater melts into the ocean the salinity level will slowly decrease. Therefore as we slowly add or decrease the salinity level in our flasks, the ocean will experience similar results. The problem our freshwater plants face is that when the sea level rises, plants living on the coastline will be exposed to saltwater coming from the ocean. If all plants are not able to tolerate the salt then all of the plants living on the coastline will start to die. As the sea level rises, more floods are predicted to break out in places close to the ocean. As a result of this, more plants will be affected by saltwater that is only used to take in freshwater.
What We Would Change if the Experiment was Redone
If we had the opportunity to redo this experiment we would’ve gotten a bigger flask to hold our plants. This would have made it easier to observe our plants and take them out of the water. We also realized because of the size of the flask we’re using we couldn’t find a stopper to cover it. We would also stir and dissolve the salt before we added it to the flask containing our plant. We added the salt to the plants without stirring it so we had to gently shake the flask so the salt would dissolve. We also realized when we were trying to put the salinity level to a certain percentage it was hard to add the exact amount of salt. This would cause us to sometimes add not enough salt or add too much salt. We would have to empty some of the water and add the salt again. Instead, to make it easier we could have weighed the salt and researched to see what percent of salinity it is.
Results
Our hypothesis stated that as we change the salinity for any of our plants we would observe changes to the plants. Our results showed over the first week that there weren’t many changes from our base plant to our experiment plant. Our saltwater plant that was also experimenting didn't have many changes either. This means that the changes to the salinity levels were not drastic enough to see visible changes in the plants. As our time was running out we increased the amount of salt in the freshwater plant to double the salinity percentage. Similarly, we decreased the salt in the saltwater plant to half of what it was in the previous class. At the start of the next class, we observed some darkening on one of the experimental freshwater plants but wanted to change the salinity levels even more. In the next class, we increased the freshwater plant to 3% salinity from 2%. For our saltwater plant, we decreased the salinity percentage from 0.75 to 0.325. The results of this included that the experimental freshwater plant showed signs of browning on the leaves. The experimental freshwater plant darkened while the base plant stayed its same vibrant color. As sea level rises and water floods onto land, we can conclude that plants will be affected by the salt increase. The experimental saltwater plant stayed the same meaning we didn't decrease the salinity amount enough. With this information, we can conclude that as global warming melts glaciers, the slight decrease in the salinity percentage will not affect plants living in the ocean. Our hypothesis also states how we thought that the plant's growth would be affected. We could not measure our saltwater plant because of its shape but we did measure our freshwater plants to see if the salinity affected the plant's growth. The freshwater base plant was 28 centimeters at the start of the experiment and the experimental plant was 29 centimeters. We saw no growth on any of our freshwater plants meaning that the plants were not in the water long enough for the plants to grow. Our base plants stayed the same throughout the experiment which means that the added salt and decrease of salt is the reason the plants were affected. Our hypothesis was partially correct as our experimental freshwater plant started to die. Although as previously stated we did not see changes in growth on any of the plants. Finally, part of our hypothesis was incorrect as the experimental saltwater plant did not die in the lowered saline levels.
Error Analysis
For the first couple of classes, we did not stir the salt before adding it to the plant. This caused the salt balance in the water to be uneven. The solid salt chunks sunk to the bottom which meant that the salt was not affecting the plant's leaves. Instead, the only area of the plant the salt could have affected was the plant's roots. Although across the experiment we did not observe any changes to the plant's root system. For better results we needed a longer amount of time where the salt increments were smaller, to better display the gradual results of global warming. We would also need a longer time period in the water because we saw no growth in the plants. Therefore, we could not observe if the salt affected the growth of the plants.
Connections
Humans are the reason global warming continues to affect our planet in many different ways. As people are becoming aware of the impact we have on our environment, steps are being taken to try to preserve our planet. But all humans are the reason that our Earth is changing for the worse. Cars, airplanes, and factories are just some examples of things that are causing our planet to heat up. Global warming continues to affect our Earth by melting glaciers, which will cause sea levels to rise, and plants and humans will start to be affected. Cities like Miami and Honolulu will be impacted as the water level rises past its current state. This means that people will have to try to make these cities safe as the water level rises, or they will have to choose to move further inland.
Global warming caused by humans will also start to affect plants living in the ocean and on coastlines. Plants are in a similar situation to humans in which as the water from the ocean rises it will start to affect their lives. Unlike humans, plants are stuck where they are and will start to die unless they can endure the salt. Humans and animals rely on plants to help produce oxygen in our atmosphere. If all glaciers melt then most plants living close to the ocean will experience flooding. Trees and other plants responsible for producing oxygen will start to die because of the abundance of salt in the water. Global warming is going to cause plants and humans to have to adapt to survive flooding that is expected to occur because of increased temperatures.
Potential Error
A potential error that could’ve occurred was giving all of the plants too much sunlight. Plants absorb the sunlight using Chlorophyll and carotenoids. This helps transform the sun’s energy into the energy that helps them survive. However, too much sunlight could have caused the plant's leaves to burn, it could affect its growth, the plant's leaves could change color, or the plant could get a disease. Therefore we put our plants under a light in the science room so it got some amount of sunlight but not too much. Another potential error that could’ve happened was adding too much salt. If we added too much salt to our plants right at the start of our experiment, we wouldn't have seen the growth and changes of the plants over time. This wouldn't have mirrored the effects of climate change over time. One last thing that could have affected our experiment was the salinity meter not telling the correct salinity in the water. This would have affected how much salt we needed to add and the results we would have observed.
Suggestions for Further Labs
Further labs related to salinity could test how salinity affects plants that live in the water and plants that live on land. The lab that we conducted only tested how salinity affects plants living in the water. Groups could water plants with salt water instead of using freshwater and observe the results.
Conclusion
Our base plants survived through their natural condition meaning that the sainty is what killed the plants. Our experimental saltwater plant stayed the while the experimental freshwater plant started to die.