Student activities. Activity 2 Water testing. Water testing experiment. Experiment and graphing results

Transcription

1 Student activities Activity 2 Water testing This activity has students doing multiple test of abiotic factors on water samples and filling in the activity sheet with their results. These results will then be displayed in graphs to compare them. Experiment and graphing results Students will be observing and then listing abiotic factors in an aquatic ecosystem. This will involve the measurement of ph, dissolved oxygen, temperature and turbidity. Select one of the sites to go to (see page 2 of the Treated wastewater booklet). 1. Ask students to list all the abiotic factors they can think of in an aquatic ecosystem (e.g. solar radiation, physical structure of surrounding water). 2. Tell students they will be testing four of these factors that relate specifically to the water: ph, dissolved oxygen, temperature and turbidity. 3. Define each of these factors and talk about why these factors are important in an aquatic ecosystem. What can naturally influence these factors, and what can humans do to influence these factors? 4. Explain to the students that they will be going out to a water body to measure ph, dissolved oxygen, turbidity and temperature. 5. Print out the Sampling instructions sheets for each testing station (laminate if possible). You may want to review the actual testing procedures before going into the field. Water testing experiment Aim To observe, understand and list specific factors in water quality. Equipment 1 x ph test kit 1 x dissolved oxygen test kit 1 x field thermometer 1 x turbidity tube 1 pencil 1 x 5 L bucket 1 x copy of the Sampling instructions sheets 1 x copy of the Water testing Activity Sheet 1 x waste bottle (e.g. empty plastic bottles) 1 x clipboard Experiment set-up 1. Set up a station for each factor (ph, dissolved oxygen, turbidity and temperature). 2. At each station, provide: Sampling instructions sheets Waste bottles The appropriate testing kit Sample bottles if you are not near the ocean. 3. Divide the students into groups of four and provide each group with: clipboards, pencils and activity sheets. 4. Explain to the students that each group will start at a different station, and rotate so they can measure all the factors. 5. Have the students fill out the site observations section of the activity sheet before beginning their measurements. 6. Have students follow the instructions for measuring each factor found on the Sampling instructions sheets.

2 Student activities 7. Have the students record their results on the activity sheet. 8. Students will then graph their results for each experiment. Upon completion, the following questions can be explored. Further class discussion questions These questions can be explored upon completing the experiments and graphing the results. 1. Why would previous weather conditions be of interest when looking at ocean conditions? Often it can take hours or days for the runoff from a storm to reach the water and travel down the river then to the ocean. Therefore, previous weather may be as important as today s weather in explaining your results. 2. How do you think the abiotic factors you observed at the site may have affected your measurements? Sunny weather may increase photosynthesis at your site, and therefore increase dissolved oxygen and ph levels. Higher flows from storms may increase the turbidity in the ocean. Soils in the watershed will affect the chemical composition of the runoff that reaches the ocean. Bathymetry will determine whether the ocean is deep or shallow and wide, which will affect dissolved oxygen and temperature. Land uses along the ocean and in the watershed will determine what type of pollutants may enter the ocean (e.g. sediment from agriculture or logging, metals and oils from roads, or fertilizers from golf courses). Extension activity Have the students compile and graph the data to demonstrate a particular pattern (in order to graph class results the teacher will need to collect all grouped records, to then share with the class): Sample graphs TEMPERATURE ( 0 C) This graph shows temperature readings at different marker points at the location. DISSOLVED OXYGEN This graph shows dissolved oxygen readings at different marker points at the location. PH LEVELS Main Outlet READING MARKERS AT LOCATION Main Outlet Main Outlet READING MARKERS AT LOCATION READING MARKERS AT LOCATION This graph shows ph levels measured at each of the marker points at the location. Create a graph comparing the results from different teams. Create a graph that shows sample statistics (e.g. the mean and standard deviation or range of different student measurements).

3 Sampling instructions ph sampling instructions Note: Take ph readings directly in the ocean. If this cannot be done safely, collect water in a bucket or a sample bottle and immediately take the ph reading. Time: 2 minutes Persons: 1 Materials: ph strips Step 1: Dip one strip of indicator (litmus) paper into the ocean for 30 seconds then pull it out. Step 2: Wait 2 minutes. Step 3: Compare the colour of the litmus paper to the ph colour key on the ph box. Step 4: Record the number associated with the correct colour match on the activity sheet. The PLOOM program monitors the health of Perth s coastline and marine ecosystems. Dissolved oxygen sampling instructions Time: 3 minutes Persons: 1 Temperature sampling instructions Time: 2 minutes Materials: Dissolved oxygen sampling kits Persons: 1 Sunlight can damage the ampoules in your dissolved Materials: Thermometer oxygen kit. Keep them shaded at all times. Step 1: Pre-rinse collection bottle with ocean water. Fill the sample cup to the 25 ml mark with your sample. Step 2: Place the glass ampoule in the sample cup. Snap the tip by pressing the ampoule against the side of the cup. The ampoule will fill, leaving a small Step 1: Dip the thermometer into the water body. Wait for the temperature to stop changing (at least 1 minute). Step 2: Read the temperature and record on the activity sheet. bubble that will help you mix the contents. Step 3: Mix the contents of the ampoule by turning it up and down several times, allowing the bubble to travel from end to end each time. Wipe all liquid from the outside of the ampoule. Step 4: Wait 2 minutes for colour development. Step 5: With the sun (or another light source) shining on the comparator (rack of coloured tubes) from directly above, place the dissolved oxygen ampoule between the colour standards for viewing. It is important that the ampoule be compared by placing it on both sides of the colour standard tube before deciding that it is darker, lighter or equal to the colour standard. Record the concentration of the best colour match on the activity sheet. Conversion Converting Fahrenheit to Celsius: C = (5/9) x ( F - 32)

4 Sampling instructions Turbidity sampling instructions Time: 2 minutes Persons: 1 Materials: Turbidity tube Step 1 (Collect your sample): Dip the tube into the water at your sampling site and fill to the top. Be Turbidity conversion chart An increase of more than 10 NTUs violates WA s water quality criteria. Distance from bottom of tube (cm) NTUs < to bottom. 7 to Step 2 (Take your measurement): Take your filled 8 to turbidity tube to a shaded spot. If there is no shade, 9 to use your body to block the sun from shining on 10 to the tube. With your hand over the opening, shake 12 to to careful to sample flowing water and not the ocean the tube vigorously. This will help to resuspend any sediment that has settled to the bottom. Look 16 to to to release water from the release valve until the disk 24 to becomes visible. Note the water level in centimetres 26 to (cm) on the activity sheet. 29 to Step 3 (Convert from centimetres (cm) to 31 to down through the tube toward the target disk on the bottom. If the disk is visible, record the water level in centimetres (cm). If the disk is not visible, slowly Nephelometric Turbidity Units (NTUs): Match your turbidity measurement in centimetres to the corresponding NTU using the conversion chart (see opposite). Record on the activity sheet. 34 to to to to to to to to to to 60 8 Over the top 60

5 Activity Sheet Water testing Location Name: Group No: Date: Site ID: Site Observations Type of water body: Weather today: Weather yesterday: Air temperature: Water appearance (e.g. clear, foamy, milky): What type of land uses are in the immediate area? What type of land uses are in the surrounding area? Are there any unusual factors potentially impacting the location? List all other abiotic factors you can observe that might be important in this aquatic ecosystem:

6 Activity Sheet Water testing Water quality results Record your results in the table below from your experiments. ABIOTIC FACTOR YOUR RESULTS COMPARE YOUR RESULTS TO ALLOWABLE RANGE Main Outlet ph ph ph ph ph ph Dissolved oxygen ppm (mg/l) ppm (mg/l) ppm (mg/l) ppm (mg/l) ppm (mg/l) Min of 6.5 mg/l for cold water fisheries and 5.5 mg/l for warm water fisheries Max of 20 C for cold water fisheries and the Temperature C C C C C max temp for warm water fish is 27 C Turbidity CM NTUs CM NTUs CM NTUs CM NTUs CM NTUs An increase of 10 NTUs from previous data DOES THE WATER MEET WA s REQUIREMENTS? (YES/NO)