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Total Dissolved Solids

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Temperature
INTRODUCTION
The temperature of a body of water influences its overall quality. Water temperatures outside the “normal” range for a stream or river can cause harm to the aquatic organisms that live there. It is for this reason that the change in the temperature of the water over a section of a stream is measured, not just the temperature at one location. If the water temperature changes by even a few degrees over a one-mile stretch of the stream, it could indicate a source of thermal pollution.
Factors that Affect Water Temperature  Air temperature  Amount of shade  Soil erosion increasing turbidity  Thermal pollution from human activities  Confluence of streams

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Thermal pollution caused by human activities is one factor that can affect water temperature. Many industries use river water in their processes. The water is treated before it is returned to the river, but is warmer than it was before. Runoff entering a stream from parking lots and rooftops is often warmer than the stream and will increase its overall temperature. Shade is very important to the health of a stream because of the warming influences of direct sunlight. Some human activities may remove shade trees from the area which will allow more sunlight to reach the water, causing the water temperature to rise.

exposure to sunlight Low Medium Low

exposure to sunlight High

Another factor that may affect water temperature is the temperature of the air above the water. The extent of its influence has a great deal to do with the depth of the water. A shallow stream is more susceptible to changes in temperature than a deep river would be.

Effects of Water Temperature  Solubility of dissolved oxygen  Rate of plant growth  Metabolic rate of organisms

 Resistance in organisms While many factors can contribute to the warming of surface water, few cause it to be cooled. One way water can be cooled is by cold air temperatures. A second, natural method of cooling a river or lake comes from the introduction of colder water from a tributary or a spring.

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Table 1: Optimal Temperature Ranges Organism Temperature Range (°C) 5 – 20 5 – 28 10 – 25 10 – 25 10 – 25 10 – 25 10 – 25 10 – 25 20 – 25

Trout Smallmouth bass Caddisfly larvae Mayfly larvae Stonefly larvae Water boatmen Carp Mosquito Catfish

One important aspect of water temperature is its effect on the solubility of gases, such as oxygen. Test cold water than in More gas can be dissolved in1 warm water. Animals, such as salmon, that require a high level of dissolved oxygen will only thrive in cold water. Test 1 Increased water temperature can also cause an increase in the photosynthetic rate of aquatic plants and algae. This can leadTest 1 to increased plant growth and algal blooms, which can be harmful to the local ecosystem. A change in water temperature can affect the general health of the aquatic organisms, thus changing the quality of the stream. Table 1 lists the optimal temperature ranges of some selected aquatic organisms. When the water temperature becomes too hot or too cold, organisms become stressed, lowering their resistance to pollutants, diseases, and parasites.

Expected Levels
Water temperatures can range from 0C in the winter to above 30C in the summer. Cooler water in a stream is generally considered healthier than warmer water, but there are no definitive standards. Problems generally occur when changes in water temperature are noted along one stream on the same day. Some sample data are listed in Table 2.
Table 2: Water Temperatures of Selected Rivers Site Hudson River, Poughkeepsie, NY Missouri River, Garrison Dam, ND Rio Grande, El Paso, TX Mississippi River, Memphis, TN Willamette River, Portland, OR Season Winter Winter Winter Winter Winter Temperature (°C) 5 3 16 7 9 Season Summer Summer Summer Summer Summer Temperature (°C) 25 14 21 29 22

Summary of Method
You will use a Vernier Temperature Probe to measure the temperature of water at one site each week.

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Temperature

TEMPERATURE Collection and Storage of Samples
1. Water temperature must be measured on site by either placing the probe directly in the stream or by collecting a sample and immediately measuring its temperature. 2. If you need to collect a sample to measure on site, it is important to obtain the water sample from below the surface of the water and as far away from the shore as is safe. If suitable areas of the stream appear to be unreachable, samplers consisting of a rod and container can be constructed for collection.

Pre-Testing Procedure
1. Position the computer safely away from the water model. Keep water away from the computer at all times. 2. Prepare the computer for data collection. 3. Plug the Temperature Probe into Channel 1 of the Vernier interface. 4. You are now ready to collect temperature data. a. Select a position on the model and place the tip of the probe into the water. b. Monitor the temperature in the Meter window for 30 seconds. c. If the temperature appears stable, simply record it on the Data & Calculations sheet and proceed. d. Select another position on the model and repeat a to c.

Column Position

A Temperature 1 (°C)

B Temperature 2 (°C)

C Average temperature (°C)

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Test 1

Testing Procedure
1. Position the computer safely away from the water. Keep water away from the computer at all Test 1 times. 2. Prepare the computer for data collection. 3. Plug the Temperature Probe into Channel 1 of the Vernier interface. 4. You are now ready to collect temperature data. a. Place the tip of the probe into the sample of Site 1. b. Monitor the temperature in the Meter window for 30 seconds. c. If the temperature appears stable, simply record it on the Data & Calculations sheet and proceed. Test 1

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Temperature DATA & CALCULATIONS

Temperature- Create a classroom chart
Stream or lake: ____________________________ Site 1 name: _______________________________ Date: __________________________________ Time of day (Site 1): ______________________

Column

A

B

C

Week

Temperature 1 (°C)

Temperature 2 (°C)

Average temperature (°C)

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2

Column Procedure: A. Record first water temperature reading at site. B. Record second water temperature reading at site. C. Average the water temperature at each site = (A + B) / 2

Field Observations (e.g., weather, geography, vegetation along stream) ___________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________

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Test 1

ADDITIONAL INFORMATION Tips for Instructors

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1. Make sure your students are using the correct experiment file. Each type of Temperature Probe (see Table 3) has its own experiment file. For example, if you are using the Stainless Steel Temperature Probe, use the file named “Test 01 Temp-Stainless1Steel”. Test 2. Which Temperature Probe should I use? All of the Temperature Probes in Table 3 will work well for water quality studies. Additional information is listed to help you decide. Test 1
Table 3: Temperature Probe Comparison Stainless Steel Temperature Probe 

no calibration required  auto-ID with LabPro  excellent chemical tolerance  Range: –25C to 125C
Vernier Direct-Connect Temperature Probe 

excellent chemical tolerance  5-foot cable  Range: –15C to 110C
Vernier Extra-Long Temperature Probe 

100-foot cable for doing depth studies  good accuracy with calibration  excellent chemical tolerance  Range: –50C to 150C 3. In some studies, water temperature as a function of depth is useful information to collect. There are two ways to accomplish this. The best method is to use the Vernier Extra-Long Temperature Probe. It has a 30-meter cable that can lower the probe directly into the water and works very well for this purpose. If you do not have one of these probes, but do have a Water Depth Sampler, you can “grab” a water sample and measure it at the surface. 4. The graph at the right shows the monthly water temperatures of the Cowlitz River in Kelso, Washington over a one-year period of time. This illustrates the magnitude of temperature change that can occur in the course of a year. A stream with less water flow than this river would be even more dramatically affected by changes in the weather, melting snow, or periods of high or low water flow. Monthly Temperatures, Cowlitz River, Kelso, WA

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Temperature 5. The effect of water temperature on aquatic organisms is actually very complicated. Not only does water temperature affect the metabolic rate of aquatic organisms as mentioned earlier, but it affects their feeding habits and reproductive cycles as well. Many animals also have different temperature requirements for different stages of their life cycles. Aquatic animals can usually tolerate slow, gradual changes far better than sudden temperature changes. 6. If taking a reading one mile upstream is not practical, take the data from a second site as far upstream as possible. Note the approximate distance between Site 1 and Site 2 on the Data & Calculations Sheet.

How the Temperature Probes Work
Stainless Steel Temperature Probe

This probe uses a thermistor to measure temperature. The thermistor is a variable resistor whose resistance decreases nonlinearly with increasing temperature. The probe is stainless steel making it very chemical resistant.
Vernier Direct-Connect Temperature Probe

This probe uses a temperature transducer to measure temperature. It produces a voltage output that varies in a linear way with temperature. The probe is covered with Teflon® FEP heat-shrink tubing. This coating protects the probe from damage in most environments.
Vernier Extra-Long Temperature Probe

This probe uses a temperature transducer and an amplifier box to measure temperature. The transducer produces a voltage output that varies in a linear way with temperature. The probe is covered with Teflon® FEP heat-shrink tubing. This coating protects the probe from damage in most environments.

Do I Need to Calibrate My Temperature Probe?
Stainless Steel Temperature Probe

No. Calibration is not required with the Stainless Steel Temperature Probe.
Vernier Direct-Connect Temperature Probe

There is usually no need to calibrate the Direct-Connect Temperature Probe yourself. Using the temperature calibration stored in the experiment file will give excellent results. For greatest accuracy, however, you could follow the two-point calibration procedures described for the Extra-Long Temperature Probe.
Vernier Extra-Long Temperature Probe

Using the temperature calibration stored in the Logger Pro program will give satisfactory results with this probe. For greater accuracy, however, you could calibrate the probe yourself. To do a two-point calibration for a Temperature Probe, follow these procedures: 1. Prepare an ice-water bath and a room-temperature bath:


When preparing the ice-water bath, stir vigorously with a magnetic stirrer and use plenty of ice (crushed ice works better than ice cubes).

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Test 1
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When preparing the room-temperature bath, make sure the water temperature has stabilized and use a high-quality thermometer. Test 1  Suspend the Temperature Probe with its tip in the ice region of the ice-water bath. 2. In Logger Pro, choose Calibrate from the Experiment menu. Click . Test 1 3. Type “0” in the edit box. This represents the temperature value 0°C. When the displayed voltage reading for Input 1 stabilizes, click Keep . 4. Move the Temperature Probe to the room-temperature water bath. Allow time for the Test 1 temperature to stabilize. 5. Type the actual temperature, as read by the thermometer, in the edit box. When the displayed voltage reading for Input 1 stabilizes, click Keep , then click OK .

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