Water Quality Testing Activity time: hrs, also pre-activity sample collection time

Transcription

1 Water Quality Testing Activity time: hrs, also pre-activity sample collection time TEACHERS: Read Woodland SS Water Quality Monitoring on page 127 and Sanitary Reporting on page 65 of Peel Water Story book. Objectives: In this activity students will do a comparative study of water from a variety of and determine the relative health of the watercourse at a particular site. A brief introduction indoors will familiarize learners with the variables to be tested. Students are encouraged to bring samples of water from watercourses close to their homes or schools while exercising extreme caution with adult supervision. Once completed, the test results will be charted and analyzed with generalized conclusions being solicited from the students. Introduction: What is good water quality? It depends on what the water is being used for (e.g. drinking, swimming, bathing, wildlife/fish, etc.) What is the natural range of factors which indicate the water is healthy? Water quality is determined by three major means: Chemical analysis water quality (ph, Oxygen, Carbon Dioxide, Nitrates, Ammonia, Phosphates) Biological indicators - invertebrates/fish change in response to the changing chemicals Physical measurements of colour, clarity, and conductivity of the water (Secchi Disk, Conductivity Meter) Normal water quality changes are based on a number of factors: A. Water source (i.e. river, lake, well, swamp) Rivers vs. Lakes moving vs. relatively still erosion potential high vs. erosion potential low non-stratified vs. stratified during the summer B. As lakes age over geological time they change from oligotrophic (low productivity) to eutrophic (high productivity) with corresponding changes in the bio-indicators and chemicals. C. Pollution nutrients from sewage and agricultural thermal pollution stormwater runoff D. Natural cycles within the ecosystem e.g. natural decomposition and decay Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 1

2 Water Quality Parameters Chemical/Test Sources Levels Oxygen (1,2) needed for cellular respiration Rivers - water turbulence in air Lakes - some from air, most produced by plants 5 ppm - good for most gill breathers 10 ppm for trout Oligotrophic High oxygen levels from bottom to surface Eutrophic High oxygen at the surface, low oxygen at the bottom Pollution and unnatural Thermal (heat) increase in heat reduction in amount of oxygen Sewage - encourages bacteria which use up the oxygen ph (2) measure of acidity H+ ions in the water supports a variety of organisms Start basic and become acidic Start acid and become more basic Acid precipitation Sewage may increase acidity Alkalinity (2) ability to neutralize acids sum of all bases mostly carbonates and bicarbonates Closely linked to the abundance of CO 2 and respiration CO 2 + H 2 O = H 2 CO 3 = bicarbonates + carbonates 50 ppm is low 200 ppm is high 50 ppm less productive 200 ppm more productive Household cleaners Sewage - increases the number of bacteria which increases the CO 2 and therefore alkalinity Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 2

3 Chemical/Test Sources Levels Hardness (2) measure of Calcium and Magnesium essential micronutrients Nitrogen (2) (Ammonia and nitrates) Calcium and magnesium are dissolved in runoff as water flow over the minerals Released through natural decay of organic matter soft 0-60 ppm moderate ppm hard ppm very hard > 180 ppm Total N for lake <.3 ppm >.3 ppm = algal bloom Ammonia >.5 ppm harmful to gill breathers Oligotrophic Eutrophic n/a n/a n/a Pollution and unnatural Decay of human sewage Decay of waste from farm feedlots Fertilizer runoff from farms and lawns Phosphorus (2) needed for ATP Natural decay, faeces and erosion of soils lake should contain < ppm or algal bloom will result n/a Human sewage Feedlot faeces Detergents *Not fertilizer Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 3

4 Chemical/Test Sources Levels Oligotrophic Eutrophic Pollution and unnatural Chloride (Cl) (2) needed for cell functions Natural salt (NaCl) deposits are the most common natural ppm normal level in rivers and lakes n/a n/a Road salt in the winter Sanitation of sewage with chlorine ( ppm) Total Dissolved Solids (TDS) (3) A measure of all the nutrients and minerals dissolved in the water. A good single measure of productivity. lake and rivers vary between 50 to 200 ppm < 100 ppm > 100 ppm All of the above could contribute Treated sewage ppm Total Suspended Solids (TSS) (4) A measure of all the undissolved solids in the water. Levels are used in comparisons only. Large increases in TSS is an indication of sewage or erosion ***Method of testing: 1 - Oxygen temperature probe 2 - Hach Kits 3 - Conductivity ITM Meter 4 - Filtration Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 4

5 Bio-indicators: Fish - the diversity of and type of species found in a natural water body can be used as an index to the quality of the water. Bacteria are a normal and essential part of the natural ecosystem. Bacteria are one of the major vectors for decomposition. Water that is used for drinking, swimming, and other consumptive uses are tested for faecal coliform. Algae - are a vital link in natural water ecosystems. Lakes and streams which have a high water quality tend to have moderate levels of many species of algae. Highly eutrophic lake or polluted lakes exhibit algal blooms with high levels of a few species. Bottom Fauna (insects and insect larva) are often collected as part of stream studies. The presence of certain bottom fauna indicate high oxygen levels, generally an indication of good water quality, and other insects indicate a low oxygen level or lower water quality. Changes in bottom fauna will also occur if there is a major change in bottom substrate (i.e. going from gravel to sand and silt) Bio-indicators show trends and are good for comparing samples collected over time at one location or comparing different locations along a water course. This data should be used to support empirical, quantitative, water chemistry testing. Collecting Water Samples: Possible locations for collection of water samples are: Local stream or river - all parameters may vary according to the specific site characteristics Tap Water - should show low nutrients (nitrates, nitrites), may show higher chlorine levels Agricultural run-off - if fertilized can show elevated nitrogen (nitrates, nitrites, ammonia) readings Sewage Treatment plant outflow may show elevated chlorine levels from the disinfecting process Well water - low oxygen, high hardness - has been underground for many years Water from a source near the school - all parameters may vary according to the specific site characteristics All samples should be collected the day of the study in sealable jars and kept refrigerated until tested. Large Mason jars work well. The surrounding land use should be recorded at each site as they may have a direct effect on the water quality. Each jar should be filled to the very top with no air remaining in the jar. Sample should be collected from the centre of streams, if possible. Water collected from the natural environment should be handled with care. The quality of the water is unknown and it may contain contaminants. Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 5

6 It is not reasonable or economically feasible for all students to do all chemical tests. To ensure consistency, teams of 2 or 3 people should test each water sample doing the same chemical test. This data can then be shared with the other students. Some tests take up to 15 minutes to complete. It is difficult to collect and analyze bio-indicators during this activity but data could be compiled over time from each group for comparison. Debrief: Did any of the water samples have higher than acceptable levels? Is this normal (i.e. due to natural processes or is there a potential water pollution problem? What levels would change with an increase in fertilizer use? What water quality variables would change if there was a sewage leak into the stream or river? Did you detect any of theses changes? Materials: Below are some suggested equipment for teachers and educators interested in testing the water quality of local, streams and ponds. Mason Jars for collecting water samples. Chemical Free Hach Just Add Water Kits Ponds and Streams Kit (Level 2) Cat. No test strips for alkalinity 50 test strips for ph 50 test strips for phosphate 50 test strips for nitrate 25 test strips for ammonia Temperature Pocket Pal Digital Meter Hach Sension 6 DO Probe (3 metre cable) Hach chemical kits come with suggested activities and curriculum ideas on diskette. Digital, chemical free portable multi-parameter ITM meter - Water Tester Tests for ph, oxide-reduction potential, dissolved solids content, and temperature Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 6

7 Safety Issues: Care must be taken when collecting the water sample (i.e. slippery surfaces, steep slopes, high and/or fast water etc.) Water test kits must be carefully handled as some chemicals are a hazard. Review of the W.H.M.I.S. material safety data sheets is highly recommended. Use of the Hach test strips is also recommended to reduce exposure to chemicals and reduce hazardous liquid waste. Dispose of wastewater from the tests in an appropriate manner. Spills of any test kit materials should be reported and dealt with immediately. Source: Developed by Toronto and Region Conservation Authority s Education Services. Contents of this publication may be photocopied provided the source is acknowledged on every page by including the following Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel Not to be adapted or reprinted without written permission of the Environment, Transportation and Planning Services Department of the Regional Municipality of Peel. Address: 10 Peel Centre Drive, Brampton, Ontario L6T 4B9 Peel Water Story, Environment, Transportation and Planning Services Department, Region of Peel 7