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pH
Another test we performed was determining the pH of the water. The pH of a liquid is the amount of H+ (hydrogen) ions present. Water contains both H+ ions and OH- (hydroxide) ions. The range of pH is on a scale of 0-14, 0 having a large amount of H+ ions, and 14 having a large amount of OH- ions. If there are more H+ ions than OH- ions, then the liquid (water in our case) is considered acidic. If there are more OH- ions than H+ ions, then the water is considered basic. A pH of 1 reveals that the amount of hydrogen ions in the solution is 10-1 g/L. A pH of 2 means that the amount of H+ ions in a solution is 10-2 g/L, and so on. Usually, pure water has a pH of 7, which is considered a neutral solution and ideal for wildlife. We wanted to determine how acidic or basic the water was, or if it was neutral.
Testing the pH is very important for determining water quality. Most organisms need the water they live in to be a specific pH value. If the
pH is changed slightly, this could amount for a huge die off of organisms since most living things are very sensitive to how basic or acidic water is. For example, a species of trout has disappeared in certain streams after scientist have account for a change in pH in the water they live in. If a body of water is very acidic, this could amount to serious problems for organisms. Most will be unable to sustain their usual lifestyle, and newly born organisms are very sensitive to a pH less than 5. When the pH is between 3-3.5, most fish will not survive, and only a few type of plants will be able to live sustainably. Between 4.5-5, most fish will be unable to hatch. A pH of 5-5.5 causes metals to be released in water than clog the gills of fish and cause deformities. Between 6.5-8.5 is ideal pH levels for living organisms. Anything over 8 can have varied effects on species, and anything over 11 is extremely lethal to any organism. Therefore, it is extremely important to monitor and determine the pH of bodies of water to protect organisms.
Usually, pH occurs naturally at a level of 7 in bodies of water. This means that the amount of H+ ions and OH- ions are equal, which is ideal for organisms living in the water. Some ways that pH is affected naturally is from certain limestone that resides in the water. Some of the chemicals and elements in the stone combine with other hydrogen or hydroxide ions to neutralize the water. Additionally, unpolluted rain is slightly acidic. The pH of rain can be lowered from volcanic ash, certain bacteria, airborne particles from wildlife, and even lightning. As a result, when the rain enters bodies of water, it can change the pH slightly, making it more acidic.
Humans have impacted the pH of water in a variety of ways. In the US, most water has a pH value between 6.5-8.5. However, increased amount of nitrogen oxide and sulfur dioxide from automobiles causes nitric acid and sulfuric acid to be released into the atmosphere. This causes the polluted type of acidic rain that is not natural to the environment. This falls to the earth and contaminates bodies of water, making them more acidic. Areas where there is a large amount of industrialization and factories are hit hard and cause the pH to change drastically. If there is no form of limestone nearby to neutralize the water, the pH will be greatly lowered and create an unsustainable environment for organisms.
When we tested the pH value of the Chicago River, it came out to be a value of 7. This means that the water was neutral. A pH of 7 gave us a Q value of 89. Any Q value between 70-90 reveals that the water is in good quality. However, Q values between 90-100 reveal excellent quality of water, so ours was not the highest. Therefore, the pH revealed that our water was still in good quality and sustainable for organisms to live and thrive in.
A Q-VALUE OF 89!
We got the results we did because there is no source of chemicals that alter the pH nearby our area of the river. The chemicals that turn into acids that reduce the pH are from factories. Our area of the Chicago River was in a forest preserve. There were no factories nearby to produce pollution to alter the pH. Additionally, it could be inferred that the river contains limestone that neutralizes the water if anything were to happen to alter the pH. This can be inferred since the pH was the exact neutral value of 7. Overall, there was no source of chemicals nearby that would alter the pH of the river, giving us a neutral value.
We tested the pH by using pH strips, which are a relatively easy test to perform. To test it, you obtain a strip from the kit and dip it in the water. The color of the strip changes depending on the pH, and then you compare it to chart that has certain colors for every level of pH. This determines the pH value of the water.
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