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DISSOLVED OXYGEN
We tested the amount of dissolved oxygen in the water. Dissolved oxygen is crucial for all living plants and animals because it provides oxygen for them. Most aquatic organisms require high levels of DO. However, there are a few organisms, like carp and catfish, can sustain low levels of DO. DO is an indicator for severe pollution. If there is a high amount of DO in the water, this indicates that there is little pollution in the area. An ecosystem with high levels of DO would be healthy, stable, and provide for many organisms in the area, making wildlife diverse. A low amount represents a lot of pollution in the water, and life for organisms would be difficult. DO is measured in parts per million (ppm). Any DO below the level of 3 ppm is stressful for most aquatic organisms and is unsustainable for life. The levels required for growth and activity are between 5 ppm and 6 ppm. Any level greater than 8 ppm is extremely good for the environment and represents nearly no pollution in the area. The lower the DO number is, the higher and more intense the pollution in the area is.
Dissolved oxygen is mostly found in the atmosphere through waves and tumbling water. Any type of disturbance, such as waves and tumbling, is able to capture the oxygen from the atmosphere. It then obtains it and brings it into the aquatic ecosystem where organisms use the oxygen to live. Additionally, aquatic plants, such as algae, produce DO through the process of photosynthesis. During photosynthesis, oxygen is a byproduct of the process. Therefore, it is released into the water when plants undergo it, adding to the overall amount of oxygen in the water. These type of rooted aquatic plants occur more naturally in rivers without an intense current, due
Humans have made a huge impact on the amount of dissolved oxygen present in bodies of water. When humans do not dispose of waste properly, this can have a poor effect on water. The waste makes its way into the water, causing the area to be highly polluted and become oxygen demanding waste. Bacteria throughout the water that is naturally occurring or from the waste then decomposes the organic waste in the water. This uses up an extremely large amount of oxygen, which shrinks the DO level rapidly. This causes the fish in the ecosystem to die off since there isn’t enough oxygen to live sustainably. Humans are the ones responsible for an event like this due to the fact that they allowed the waste to enter the water since it wasn’t disposed of properly. Moreover, urban and agricultural runoff has affected DO. Humans add fertilizer and other chemicals to grassland that eventually enters the water system. These unnatural chemicals and nutrients create an algal bloom in the water. The algae is then eaten by decomposers who use a large amount of oxygen during the decomposition process. Once again, this leads to a decrease in DO and an eventual die off of many organisms in the ecosystem. This process, eutrophication, arises from human activities of land.
to the fact the current is able to disturb the plant frequently and prevent it from undergoing as much photosynthesis as stable rivers. Furthermore, the amount of DO occurring naturally in the water depends on the water temperature. Gases are able to dissolve more easily in low temperature waters. Bodies of water with cooler temperatures will therefore have more DO as compared to another body of water with a higher temperature.
The Chicago River
For our data test, we acquired an average of 11.5 ppm of DO in the Chicago River. This was an extremely pleasing result. 11.5 is a very high level for DO in any body of water. This gave us a Q (quality) value of 92. Any Q value above 90 represent excellent quality of water. Therefore, the area in the Chicago River that we tested is very sustainable for life and organisms in the water. They are able to thrive and live stable lives due to the high amount of DO present. The water is highly unpolluted and does not have a source of contamination nearby.
Most likely, there is no nearby source of pollution for the water. The river is not surrounded by fertilizer because if it was, the DO would be reduced by the decomposers. Therefore, we were able to acquire safe and stable results because human activities affecting the water quality were not entering the river. There was no source of contamination nearby, which made the river sustainable fort thriving organisms.
A Q VALUE OF
92!
To record the amount of dissolved oxygen found in the river, we used the ChemMets, K-7512 kit. We first filled the sample cup with the river water to the 25 mL mark. Next, we inserted the ampule into the sample cup and broke the tip against the edge. The water from the river went into the ampule and then we mixed the contents in the ampule by inverting it. After letting the contents mix inside the ampule, the liquid inside the ampule changed to a shade of blue. We then compared the color of our components with the color of the comparator to receive our results.
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