Measuring Dissolved Oxyg Instructions for the La Motte Field-Test Kit

Transcription

1 Then, immediately add 8 drops of alkaline potassium iodide azide to the water sample Recap the bottle and shake to mix. Immediately add 8 drops of manganous sulfate to the water Record the temperature of the water where you collected your sample in degrees Celsius. Determine the maximum percent dissolved oxygen by using the graph on the inside of this folder. Find the water temperature value on the top scale. Find the DO reading in mg/l on the bottom scale. Draw a line between these two points. Where the line crosses the sloping saturation scale is the maximum DO percentage. Measuring Dissolved Oxygen Oxyg Fill the glass bottle with your water sample, being sure to fill it completely. Cap it while the bottle is still underwater. You should be able to turn the capped bottle upside down and not see any air bubbles. Remove the cap from the water sample bottle. You will be adding chemicals to a very full bottle, and it may overflow slightly. When the precipitate settles below the top of the bottle, add one level spoon of sulfamic acid powder to the water sample bottle. Recap the sample bottle and gently shake until the precipitate has totally dissolved. Measuring spoon for sulfamic acid powder Without moving the plunger, insert the titrator tip into the opening of the glass titration tube cap. Gently depress the titrator 1 drop. plunger to add 1 dr mix. op. Swirl to Repeat, adding 1 drop at a time and swirling to mix after each drop until the water sample turns a pale yellow. Carefully remove the titrator without disturbing the plunger and add 8 drops of starch indicator solution. Replace the cap on the glass titration tube and swirl. The sample should be bluish gray. Without moving the plunger, continue titration one drop at a time until the sample is colorless. (If you hold a piece of white paper behind the sample, it will be easier for you to tell when it s clear.) Read and record the amount of titrant used by reading the amount where the titrator tip meets the scale. Each small division on the scale equals 0.2 ppm. This number equals the mg/l of dissolved oxygen in the sodium sodium sodium The solution will be clear yellow to orange. The water sample is now fixed, meaning that air will not affect it. You will now begin the titration, which means adding a chemical drop by drop, swirling to mix after each addition, until the desired color change has occurred. Fill the glass titration tube to the 20 ml line with the fixed water Titration tube Titrator Cap the titration tube. Insert the titrator into the plug in the top of the sodium sodium thiosulfate titrating solution. Fill the titrator with the sodium thiosulfate solution by turning the bottle upside down and slowly pulling the plunger of the titrator until the bottom of the plunger is even with the zero mark of the titrator scale. Make sure there are no air bubbles in the titrator.

2 Determining ph A set of two wide-range ph comparators contain 16 permanent color standards. Liquid ph indicators are dyes that change color according to the ph of the solution. The solution color is matched to the color standards representing known ph values. 1. Rinse the test tube with some of the water from the test site. 2. Fill the test tube to the line with the sample water. 3. The sample should be tested quickly because changes in temperature can affect ph values. 7. Add 10 drops of Wide Range Indicator to the water 8. Cap the test tube and mix by shaking. 9. Cap the Wide Range Indicator and return it to the kit. 10. Get the two Comparators from the kit. 12. Hold the Comparator up so that you can find the color your sample is closest to, but don t use direct sunlight or an unevenly lit background. Match the sample color to a standard color. 13. Record the number of the matching standard as ph. 4. Locate the Wide Range Indicator in your kit. 5. Uncap the Wide Range Indicator. 6. Invert the Wide Range Indicator over the test 11. Put the sample test tube into the Comparator with colors closest to the sample color. tube with the water Counting Fecal Coliform Colonies Instructions for Coliscan Easy Gel Coliscan is a quantitative method for identifying and differentiating coliforms and fecal coliforms from other bacteria in water. 3. Tightly cap the Coliscan and water mixture and gently shake. 4. Pour the Coliscan and water mix into a pretreated Petri dish. Carefully swirl the mixture to cover the bottom of the Petri dish. 5. Cover and set the Petri dish on a level surface until the liquid forms a gel, about ½ hour. 1. Keep Coliscan medium chilled until you mix it with the water 2. Use a sterile calibrated pipette (eyedropper) to add 3 ml of sample water to the Coliscan medium bottle. 6. Tape the Petri dish shut with clear tape. 7. Take the plate back to school. Place the Petri dish in a warm place ( o C). Incubate for hours.

3 Measuring Water ater Temperatur emperature e Change We can measure temperature change from day to day, but a very important measure is the change from one part of a river to a part of the same river downstream on the same day. (The segment between the two is called a reach. ) Water temperature affects the rates of photosynthesis and plant metabolism. Warmer water holds less dissolved oxygen. A significant difference in water temperature between two sites on the same stream could severely impact aquatic life in the stream. 1. At the site where water quality tests are being performed away from the shore, lower the thermometer 4 inches below the water surface. Hold the thermometer securely during this procedure. 2. Keep the thermometer in the water until a there is a constant reading, about 2 minutes. 3. Record the temperature in degrees Celsius. 4. As soon as possible, go up stream within the reach of your testing and repeat Steps Determine the temperature change for that reach using the following equation. Temperatur emperature e downstream Temperatur emperature upstream = Temperatur emperature e change Measuring Biochemical Oxygen Demand (BOD) We measure BOD by comparing the amount of dissolved oxygen present in a freshly collected water sample with the amount of dissolved oxygen in a second sample collected at the same time and place but allowed to sit for five days under special conditions so that the bacteria in the sample have time to work. The difference between the dissolved oxygen in the two samples is how much oxygen the decomposing bacteria used to oxidize the organic material in the water during the 5-day incubation period. The amount of dissolved oxygen used over 5 days is the BOD. Most organisms require oxygen, including the bacteria that decompose organic matter. When aerobic bacteria decompose organic material, they break it down by oxidation (combining with oxygen). BOD is an abbreviation for biochemical oxygen demand, a measure of how much oxygen these bacteria use in the aerobic oxidation of organic matter To measure BOD, you will take a sample of stream water, and place it in a paper bag in a cool, dark place for five days. After five days, you will do a dissolved oxygen test on your water The BOD is the difference in mg/l between this test and the disoolved oxygen test result you obtained in the field study.

4 Measuring Phosphates 1. Fill a test tube to the 10 ml line with stream water 2. Fill the pipette to the 1.0 ml line with phosphate acid reagent. Add the phosphate acid reagent to the stream water sample in the test tube. Cap the test tube and mix by shaking. 3. Use the 0.1 gram spoon to add one level measure of phosphate reducing reagent to the sample in the test tube. Cap the test tube and mix until dissolved. Wait 5 minutes for the reaction to occur. 4. Set up the comparator (the black box): Place the axial reader on a table with the 12. If the color of the test sample is darker than the color of the second color standard, carefully move the comparator so that the bottom of the axial reader and the bottom of the comparator are even. Compare the test sample with the standards in the lower left-hand corner of the comparator.if the color of the test sample falls between the two standards, record the result as the average of the two values in mg/l. open mirrored side facing you. Put the octet comparator in the open slot of the axial reader so the labels face you. The comparator bottom should rest on the table. 5. Fill two test tubes to the 10 ml line with untreated stream water These test tubes will be used as blanks. 6. Insert the sealed distilled water standard ampoule into the square hole on the left side of the comparator. 7. Insert the test tube with treated solution from Part 2 into the axial reader slot directly behind the distilled water ampoule. 8. Insert the two untreated blank test tubes into slots in the axial reader on either side of the treated test solution. 9. Slide the comparator down until the top is even with the top of the axial reader. Hold the comparator so light shines down through the test tubes. Compare color in the center test tube (you are looking through the distilled water ampoule and your treated water sample) to the colors on either side of it in the top left corner of the comparator. 10. If the color of the test sample is less than the color of the lowest value (left of your sample is 0 ), record the result as zero. 11. If the color of the test sample matches the valule to the right of your sample, record the result as the value of that color standard in mg/l. 13. If a color match is not made with the standards on the left-hand side of the comparator, move the test sample and the blank tubes to the righthand side of the axial reader. Move the ampoule of distilled water to the hole on the right side of the comparator. Be sure the test solution is directly behind the distilled water ampoule. 14. Compare the test sample with the standards on the right side of the comparator using the technique detailed in Steps 8-12.

5 Determining Total otal Dissolved Solids Instructions for Oakton TDSTestr 1 meter Total dissolved solids increase the conductivity of water. The TDSTestr 1 converts sample conductivity to a reading of TDS in ppm. (Note: mg/l = ppm) TESTING THE WATER SAMPLE T(The water sample is tested in place. That means the meter is placed in the actual body of water ater.).) 3. Dip the meter s electrode into the water 4. Hold the electrode in the sample until the meter reading remains constant, about 10 seconds. 5. Remove the electrode from the sample and record the reading. 6. Press the ON/OFF button once to turn the meter off. The display reading will be blank. 7. Rinse the electrode with distilled water. 8. Recap the meter. 1. Remove the cap from the TDS meter. 2. Press the ON/OFF button once to turn the meter on. The display will read 000. Measuring Nitrates Nitrate is reduced to nitrite by chemical reduction. Nitrite forms a reddish purple when sulfanilamide and NED are added. This color is matched to a color standard to determine the nitrate level. 1. Fill a test tube to the 5 ml line with the water 2. Add one Nitrate # 1 tablet to the test tube. 3. Cap the test tube and mix until the tablet disintegrates. 4. Add one Nitrate # 2 CTA tablet to the test tube. 5. Recap the test tube and mix until the tablet disintegrates. 6. Wait approximately 5 minutes. 7. Insert the Nitrate-Nitrogen Octa-Slide Bar into the bottom of the Octa-Slide Viewer. 8. Insert the test tube into the Octa-Slide Viewer. 9. Hold the Octa-slide Viewer between yourself and a light source, but not direct sunlight or an unevenly lit background. Light should enter through the back of the Octa-Viewer. 12. Slide the Octa-Slide Bar inside the Octa- Viewer until the visible color standard matches your sample color. 13. Record the number shown below the visible color standard as Nitrate-Nitrogen ppm (mg/l). 14. Convert to nitrate using the following equation: Nitrate-Nitr Nitrogen en ppm X 4.4 = Nitrate ppm

6 8. Look down into each tube at the black dot. If the Std column dot and the Sample column dot are equally cloudy, note the total amount (in ml) of turbidity reagent added. Use the table below to determine the JTUs. If the Sample column dot is still cloudier than the Std column dot, continue to Step 9. Remember, you are matching the cloudiness of the two columns, not color. Ignore color differences between the two columns. Continue to add turbidity reagent until the clarity of the black dot appears equal in both tubes. Record the amount of turbidity reagent added. 10. Use the following table to determine the turbidity in JTUs. 9. Add turbidity reagent in 0.5 ml increments to the standard ( Std ) water tube. Gently stir the column after each addition and check turbidity by viewing the black dots in each tube. Turbidity Turbidity is a measure of water clarity. The greater the turbidity, the less clear the water. Turbidity is caused by solids suspended in water that reduce the passage of light through the water. Suspended materials can include many substances such as soil particles (clay, silt, and sand), algae or other forms of plankton, and bacteria. Soil particles range in size from less than mm (clay) to to mm (silt) to to 2.0 mm (sand). High turbidity can damage fish and other organisms, and interfere with their ability to find food. In this activity, you will measure turbidity using a test kit that compares the turbidity of a water sample with distilled water. Your results will be measured in Jackson Turbidity Units (JTUs). 1. Choose a sampling site away from the shore and below the surface of the water. 2. Fill the Sample turbidity column to the 50 ml line with a sample of this water. If the black dot on the bottom of the tube is not visible when you look down through the water column, pour out half the sample so that the tube is filled to just the 25 ml line. 3. Fill the Std turbidity column with an equal amount of distilled water; this is the standard. 4. Look down through the water in each tube to the black dot at the bottom. If the dot is equally clear in both tubes, turbidity is zero. If the dot in the Sample column is less clear than in the Std column, continue to step Vigorously shake the closed bottle of standard turbidity reagent. 6. Fill the pipette (eyedropper) to the 0.5 ml line with the turbidity reagent and add to Std column. 7. Gently stir the Std column to mix the turbidity reagent in the water.