Dissolved Oxygen

Dissolved oxygen also known as DO is the amount of oxygen that is dissolved in water. Dissolved oxygen is necessary for lakes and rivers to be considered healthy because aquatic life need oxygen in order to survive. As a result of low dissolved oxygen, fish will start to drown. Dissolved oxygen gets into the water in several ways such as waves. The atmosphere increases the amount of dissolved oxygen in water as the surface contact of the water increases. In addition aquatic plants such as algae add oxygen into the water through photosynthesis. These plants need light in order to carry out photosynthesis. As a result, dissolved oxygen levels are higher in the (late) afternoon and lower at dawn.

Testing For Dissolved Oxygen

There are several ways to test for dissolved oxygen in a water source. Once way is though a chemical test called the Winkler Drop Titration Method. This test is performed five days after the water sample is taken. This test is not as accurate as a test for biodegradable wastes because it only shows the amount of dissolved oxygen present that day.

Dissolved Levels And What They Mean

The higher the number of dissolved oxygen the better because then there is enough oxygen present for the survival of all aquatic life. It is impossible to predict the minimum dissolved oxygen levels due to the fact that different aquatic organisms survive at different dissolved oxygen levels. Everyone knows that fish are cold-blooded animals. As a result, they use more oxygen at higher temperatures. In addition, a high level of dissolved oxygen is good because it makes water taste better.
Several scientific studies suggest that 4-5 ppm (parts per million) is the smallest amount that can support a diverse aquatic population. A 9 ppm level of dissolved oxygen is good for fishing. Levels of dissolved oxygen that are below 3 are dangerous because lot of fish can’t survive at this level.

Results

The results of dissolved oxygen taken on the North Channel of the Chicago River are listed below:

Site	Dissolved Oxygen
1	10 (mg/L)
2	8 (mg/L)
3	9 (mg/L)

These results show us that the river has high levels of dissolved oxygen. These levels are good enough for fishing and are able to support a diverse fish population. These results are also nowhere near dissolved oxygen levels of 3 or less, which are dangerous because aquatic life can’t survive at low levels of dissolved oxygen.

Influences

Temperature has a great influence on dissolved oxygen. Warm water tends to hold less dissolved oxygen than cold water. As a result, dissolved oxygen levels tend to be higher in the winter than in the summer. Overpopulation of aquatic life influence dissolved oxygen levels because there are more organisms present and as a result they use up dissolved oxygen in greater amounts. Runoff from urban areas that contain phosphates and nitrates (fertilizers, detergents, soaps etc.) reduce dissolved oxygen levels. This causes aquatic plants, such as algae to grow at a rapid rate. Thus they tend to die quickly because sunlight gets blocked and photosynthesis can’t occur without the presence of sunlight. As a result, bacteria need to feed on and decompose these aquatic plants aerobically. Since bacteria need to use oxygen to decompose the dead plants, thus the level of dissolved oxygen decreases.
Governments should ban the use of phosphate soaps and detergents in order to keep our water sources clean. Citizens should also find a way to reduce the amount of fertilizer they use. Governments need to find a way to stop runoff such as planting plants and trees near bodies of water to absorb runoff. Citizens should be informed that their household products are causing our water sources to become contaminated. If they knew this information hopefully, they could take strides to keep these sources clean.

Turbidity

Turbidity is the measure of the clearness of water. The murkier water is, the greater the turbidity. The amount of light that is able to pass through is dependent on the amount of suspended particles that are present. The more suspended solids there are, the less light that is able to pass through to organisms living within the water. Turbidity is important to aquatic life because sunlight is needed for photosynthesis. If turbidity is too great, plants are not able to grow, causing other organisms to die as well.

Testing Turbidity

There are several ways to measure turbidity. The most accurate way is by using an electronic turbidmeter, which measures the amount of light that is able to pass through water. Another way to measure turbidity is by using a secchi disk. The secchi disk is lowered into the water until it can no longer be seen. This depth is then recorded.

Turbidity Levels and What They Mean

Turbidity	Amount of fish per acre	Amount of plankton caught in nets
Less than 25	162	12.8
25-100	94	1.6
Over 100	29	1

Basically, what can be inferred from the table above is that as the turbidity increases, the amount of life decreases. This is due to the amount of light reaching organisms. Without light, plants cannot grow, and therefore not as much fish can survive.

Results

The results of the turbidity levels found in the North Channel of the Chicago River are listed below:

Site	Turbidity
1	44 cm
2	38.5 cm
3	27.5 cm

These results show that the turbidity is fairly good, but can be better. There is a fair amount of sunlight passing through, sustaining a good amount of aquatic life in the water.

Influences

Turbidity can be influenced by soil erosion, waste discharge, urban runoff, channelization, increased flow rate, algae growth, the stir of bottom sediment, and other factors. Several of those factors are influenced by humans as well. Cultural eutrophication significantly decreases the amount of light that is able to pass through because of the algae blooms, which surface the water.
We can decrease the levels of turbidity by reducing the amount of waste we discharge into the water. We can also decrease the amount of fertilizers and other nutrient-high products in order to reduce cultural eutrophication.

Total Dissolved Soilids

The universal solvent is also another word for water because it can dissolve many things in it. Many materials are dissolved and carried away when water interacts with the atmosphere, biosphere, rocks and soil in a watershed. All suspended solids that may or may not pass through a filter are total dissolved solids.
A constant level of minerals in the water is necessary for aquatic life. Changes in the amounts of dissolved solids can be harmful because the density of total solids determines the flow of water into and out of an organism's cells. Many of these dissolved solids contain chemicals, such as nitrogen, phosphorus, and sulfur that are the building blocks of molecules necessary for life.

Testing Total Dissolved Solids

A 100mL sample of water is collected. The water sample is poured into the beaker and allowed to evaporate. Then the beaker has to cool to room temperature before weighing. The beaker is then weighed again. The first weight is subtracted from the second weight and multiplied by 10,000 to determine the mg/liter of total dissolved solids in the sample.

Total Dissolved Solid Levels and What They Mean

Concentrations of total dissolved solids that are too high or too low may limit growth and lead to the death of many aquatic organisms. High concentrations of dissolved solids may also reduce water clarity, contribute to a decrease in photosynthesis, combine with toxic compounds and heavy metals, and lead to an increase in water temperature. High concentrations in drinking water may give the water an unpleasant taste and could result in a laxative effect.

Results

The results of the amount of total dissolved solids found in the North Channel of the Chicago River are listed below:

Site	Amount of Total Dissolved Solids
1	152.2 mg
2	27.7 mg

Influences

Some dissolved solids come from organic sources such as leaves, silt, plankton, industrial waste and sewage. Some dissolved solids come from inorganic materials, which may contain calcium bicarbonate, nitrogen, iron phosphorus, sulfur, and other minerals.

Total Phosphates

Phosphorus is an element that is necessary for plant and animal growth. Animals use phosphorus bone growth as well as for reactions within the body allowing it function. Plants use phosphorus in order to grow, which provides food for fish.
Phosphates can be found in several forms. Orthophosphates, which are found in wastewater, are produced naturally. Polyphosphates are used for the production of laundry detergents as well as for treating water boilers. Organic phosphates are produced by living organisms and the breakdown of organic pesticides.

Testing for Total Phosphates

One way of testing for total phosphates is by testing the color change of a water sample. In order to do so, a water sample is taken. A powder is then added to the sample. If the sample changes to a blue-violet color, it can be inferred that there is phosphate present. The color is then compared to a scale in order to figure the amount of total phosphates.

Total Phosphate Levels and What They Mean

Amount of Total Phosphates	Significance/Meaning
0.01-0.03 (mg/L)	Water is uncontaminated
0.025 (mg/L)	Increases rate of eutrophication
0.1 (mg/L)	Maximum for rivers and streams

Results

The results of the amount of total phosphates found in the North Channel of the Chicago River are listed below:

Site	Amount of Total Phosphates
1	0 (mg/L)
2	3 (mg/L)
3	5 (mg/L)

The average of these results exceeds the maximum acceptable amount of total phosphates by far. These large amounts of phosphate cause plants to grow at an exceedingly fast rate, a process called eutrophication. This may produce an algae bloom, which are thick layers of green slime that cover the surface of water. These algae blooms are harmful to organism living within the water because they decrease the dissolved oxygen level by preventing air from contacting the water. They also increase the amount of heat going into the water because of their heat absorbent characteristics. This furthers the decrease of dissolved oxygen. Algae blooms also decrease the amount of sunlight that reaches plants in the water, causing them to die. This then kills off many other organisms living in the water.

Influences

The amount of total phosphates is influenced by human or animal wastes, fertilizers, pesticides, industry, soaps, and the disturbance of land. Humans have much of an influence on the amount of total phosphates that flow into rivers from agricultural runoff, sewage, detergents, and more. Algae blooms are caused by cultural eutrophication, which is human-caused eutrophication. As shown earlier, algae blooms are a result of a large amount of phosphates added into water. This can greatly disturb aquatic life by killing many plants and other organisms living in the water.
We can reduce the amount of phosphates going in to the water, by cutting down on the amount of fertilizers we use especially in agriculture and lawns.

BOD

Biochemical Oxygen Demand also known as BOD, provides testers with an indication of how much biodegradable waste is present in a water source. Biodegradable wastes are wastes that can be broken down by nature. This biodegradable waste is broken down as aerobic bacteria feed on it. Aerobic bacteria are bacteria that use oxygen. The more oxygen that these aerobic bacteria use the less is available for other aquatic life. A high amount of BOD means that the water source has a lot of bacteria. Having a lot of bacteria present in a water source is not a good thing because bacteria use oxygen as they eat and breakdown biodegradable wastes.

Testing for BOD

Chemical tests are performed in order to indicate how much biodegradable waste is present in a water source. The test is usually performed five days after the samples are taken. BOD is a more accurate test than Dissolved Oxygen known as DO because it gives an image of the water quality by including the long-term effects of biodegradable wastes on Dissolved Oxygen (DO). In addition, DO tests only show the DO level at the time the test was performed.

BOD Levels and What They Mean

BOD Levels	Significance/Meaning
1-2 (mg/L)	Super clean water with little biodegradable waste
3-5 (mg/L)	Fairly clean water with some biodegradable waste
6-9 (mg/L)	A lot of bacteria and biodegradable waste present
10 (mg/L) and above	Very bad water quality with lots of bacteria and biodegradable waste present

Results

The lower the amount of BOD, the healthier the water source is because it has little amounts of bacteria and biodegradable waste. The results are shown in the table below:

Site	Amount of BOD
1	0 (mg/L)
2	17 (mg/L)
3	2 (mg/L)

Based on the results above the North Channel of the Chicago River has a low amount of BOD. This means that there is little biodegradable waste and bacteria present. There must have been an error that occurred at the second site due to the fact that the value (17) is out of place. This could have happened due to a mix up on the procedure or the place that the sample was taken from.

Influences

Humans have a negative influence on BOD. The use of fertilizers (agricultural runoff), which are high in nitrates and phosphates can cause algae and other aquatic plants to grow at a rapid pace. As a result, not a lot of sunlight can get into the water causing these plants to die fast. Thus the bacteria is in charge of breaking down these dead plants. They go though this process using oxygen to decompose the waste. Since there is a lot of waste in the form of dead aquatic plants the bacteria have to use more oxygen to decompose the large amount of waste. The bacteria are using up too much oxygen and as a result they lower the oxygen present in water. Thus other aquatic life don’t have enough oxygen and die. The water source will usually tend to have an odor.
Waste from industries and salt used to melt ice from streets also have devastating
effects .Runoff from industries stir up the organic wastes trapped in the bed of the body of water. As a result similar effects such as the ones listed above can occur.
Humans should use less fertilizer in general to prevent the problems listed. They also should plant trees close to bodies of water to absorb runoff. As a result, the runoff would not reach the body of water. In addition, the height of bridges over bodies of water should be increased to prevent salt from getting into the water. If humans apply some of these changes they can keep bodies of water clean.

Nitrates

Nitrates are chemical compounds that are made from the elements nitrogen and oxygen. All plants and animals need nitrogen in order to make proteins, to grow, and to reproduce.
When plants and animals die, proteins are broken down by bacteria forming ammonia. Ammonia is broken down by other bacteria to form nitrite. Ammonia and nitrite are both poisonous to animals. Nitrite is then consumed by a third type of bacteria which forms nitrates. However nitrates can be used by plants in order to grow. This recycling of nitrogen through the environment is called the nitrogen cycle.

Testing for Nitrates

Nitrates can be tested for in a variety of ways. Most tests involve a color metric change. Some kits measure this change through electronic means, others use a simple color wheel comparator.

Results

The results of the amount of total nitrates found in the North Channel of the Chicago River are listed below:

Site	Amount of Nitrates
1	0 (mg/L)
2	1 (mg/L)
3	1 (mg/L)

Influences

Nitrate is a major ingredient in most fertilizers. When it rains, varying amounts of nitrates wash from farmlands and lawns into nearby streams. Nitrates can also enter streams from animal wastes and sewage.
Nitrates can be harmful to humans. It is broken down in our intestines becoming nitrite. Nitrite affects the ability of red blood cells to carry oxygen. If infants consume water high in nitrite/nitrates, they may suffer from a serious condition called methemoglobinemia or blue baby disease. Wells contaminated by sewage or agricultural run off are a major concern in some areas. Nitrites can also cause serious illnesses in fish.

pH of Water

The pH level measures the hydrogen ion concentration of water. The pH scale ranges from 1 to 14. Water with a pH of 7 is considered to be neutral. A pH of 7 has an equal concentration of H+ and OH- ions. If the pH is less than 7, the water is classified as an acid, meaning that there are more H+ ions than OH- ions. If the pH is more than 7, the water is classified as a base, meaning that there are more OH- ions than H+ ions. On the pH scale, one-unit change equals 10 times the strength of the acid or base. For example, a change from 6 to 4 would increase the acidic strength times 100.
Organisms are sensitive to pH. Therefore, the pH has to be at a certain level in order to sustain life.

Testing for pH

Testing for pH requires a very basic procedure. It is measured by using pH paper, which changes color according to the pH level. This color is then matches to a scale, determining the pH.

pH levels and What They Mean

A tolerable pH range for organisms is from 5.0 to 9.0. Fish tend to avoid pH levels that are too below or too above this range. If the pH level is too high or too low, organisms are not able to survive for an extended period of time, if able to survive at all. For example, at a pH level of 4.3, carps die out within 5 days. Also, at an unsuitable pH level, some fish eggs are able to hatch, but they tend to be deformed. Therefore, a certain pH level is very important to aquatic life, otherwise if not maintained; an ecosystem could be left completely imbalanced.

Results

The results of the pH level found in the North Channel of the Chicago River are listed below:

Site	pH Level
1	6
2	8
3	8

The results found show that the pH levels in the North Channel of the Chicago River fall well between the tolerable range of pH. Thus, these levels are acceptable in order to sustain aquatic life.

Influences

The level of pH is significantly influenced by acid rain. Human activities, such as the use of cars and industries, release nitrogen and sulfur oxides. Water from rain mix with these oxides to produce nitric and sulfuric acids. When these resultant acids fall into bodies of water, this decreases the pH level of the water, making it more acidic.
In order to control air pollution, industries and cars can use special equipment to reduce the amount of pollution that goes into the air, solving acid rain problems.