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Water Testing

Water Testing. By Lin Wozniewski (lwoz@iun.edu). How Do You Tell If There May Be a Problem Somewhere & the Water Should be Tested?. High population density next to water High industrialization next to water Agriculture next to water “Straightened” river or artificial lake shores

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Water Testing

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  1. Water Testing By Lin Wozniewski (lwoz@iun.edu)

  2. How Do You Tell If There May Be a Problem Somewhere & the Water Should be Tested? • High population density next to water • High industrialization next to water • Agriculture next to water • “Straightened” river or artificial lake shores • Garbage along/in water • Shallow water bottom

  3. How Do You Tell If There May Be a Problem Somewhere? • No Fish/Dead Fish • People complaining of headaches etc. • Readings on key indicators higher/lower than normal • Large changes in readings from one area to another • “Normal” readings where you would not expect them – need to look @ unexpected chemistry • New populations of species

  4. Pollution or Contamination? • It is a pollutant if it is supposed to be there, but the substance is present in higher quantity than it should be. • Fertilizers, some ions, etc. • Sometimes metals are thought of as contaminants, but many soils contain arsenic and mercury naturally • It is a contaminant if it is not supposed to be there at all • Plastics

  5. Possible Types of Pollution • TOXIC • heavy metals and lethal organic compounds • iron, mercury, PCBs • THERMAL • water heated by urban runoff or industry • streets, nuclear power • ORGANIC • decomposition of once-living material • human & animal waste, algae • INORGANIC • suspended & dissolved solids • silt, salt, minerals • BIOLOGICAL • introduction of non-native species (zebra mussels)

  6. How Do We Test for These Types of Pollution? • DO (Dissolved Oxygen) • BOD5 (5 Day Biological Oxygen Demand) • pH (Test for acidity) • Conductivity (TDS- Total Dissolved Solids) • Turbidity (How Clear is the Water) • Temperature (Thermal Pollution) • Colorimetry (Test for metals) • Coliform (Test for Organic Pollution) • Ion tests (Chlorine, phosphate, nitrogen, etc • Chlorophyl a

  7. Dissolved Oxygen • Measures how much oxygen is dissolved in the water and available for plants and animals to breath • Sources • Dissolved air • Photosynthesis • Measured with a probe • Best if done in the water body – can be done up to two hours later • Because of temperature dependence, it is measured in % Saturation

  8. Amount of Dissolved Oxygen (mg/L) your water sample would need to be 100% Saturated at the given temperature.* * @ Sea Level

  9. Calculate % Saturation: __DO mg/L__(your sample) Max DO mg/L(from chart determined by water temp) X 100% Example at 19º C: 8.0 x 100% = 84.6% 9.45 State Standard > 5 mg/L, not < 4 mg/L

  10. Using the DO Probe • The probe has to be filled with solution • The probe has to be warmed up for 10 minutes before use. • The TI has an internal calibration curve. You can use it, or do a calibration set yourself

  11. BOD 5 day • Measures how much of the dissolved oxygen is used up during the course of 5 days • DO measures are taken at the same time as collection every day for 5 days • Tells about how much of the oxygen dissolved in the water is being used up by microorganisms & hence how much is available to fish. • Is confounded by COD (Chemical Oxygen Demand) • Measured on water taken back to lab

  12. BOD5 • DO(Original sample) – DO(Day 5) = BOD5 Typical range for BOD5 = 0 to 6.3 mg/L Indiana Average = 1.5 mg/L

  13. pH • Measure of how acidic or basic the water is • From 0 (very acidic) to 14 (very basic) • Influenced by geology, rain, and discharge from point sources • Affects toxicity of other chemicals; many aquatic organisms are very pH-sensitive • Changes with temperature, in response to high levels of photosynthesis; related to alkalinity • Typical range for pH = 7.2 to 8.8 • Indiana Average = 8.0 • State Standard = between 6 - 9 • Due to the state’s limestone geology, Indiana surface waters will typically have a pH that is relatively basic (> 7).

  14. pH • Can be measured right in water body • Is a measure of how much pollution: Sulfur Oxides, Phosphate, Nitrogen Oxides, and Carbon Dioxide is dissolved in the lake since most of these form weak acids in water • Uses a sensitive glass electrode that MUST be kept wet at all times. • Electrode MUST be taken out of the buffer solution prior to being placed in water to be measured • Should not need to calibrate

  15. Alkalinity • A measure of how much buffering capacity the body of water has. • If acid is put in pure water, the pH will change a lot. • If acid is put into a buffer, the pH will change very little – at least until the buffering capacity is reached. • Living systems have natural buffering mechanisms which are added to the water. • Limestone also has an ability to add buffering capacity.

  16. TDS (Total Dissolved Solids) • A conductivity test is used as a measure of TDS since most dissolved solids are ionic • Used in connection with pH as a measure of the amount of ammonia, phosphate, nitrate, etc. dissolved in the body of water • Can be measured right in the body of water. • Probe MUST be inserted into water far enough for water to cover hole in side of probe

  17. Total Dissolved Solids

  18. Turbidity • A measure of how clear the water is • Fish can not survive if they can not see food • Sample is compared with a standard that comes with the machine • Sample must be mixed but not shaken (stirred, not shaken) because water bubbles will confound the test • Is a measure of how much material is suspended in the body of water • Typical range for TURBIDITY = 0 to 173 NTU • Indiana Average = 36 NTU

  19. Turbidity • NTU - Nephelometer Turbidity Units: a unit of measurement commonly used in electronic turbidity meters that indicate how far light can penetrate into a water sample before the cloudiness of the sample cuts into the light.

  20. Secchi Disk • A different way of measuring the turbidity of the water. • A disk with black and white areas is attached to a cord that has knots in it. • The disk is lowered slowly into the body of water until it disappears. • The point on the rope that just touches the water is noted • The disk is pulled out and the depth at which the disc disappeared is noted. • Secchi Disks measure the water clarity at many depths & can not be connected to turbidity directly

  21. Temperature • Must be done in the body of water • What we are looking for is a difference in temperature in the body of water that might indicate thermal pollution • Temperature of the water will determine how much oxygen can be dissolved into the water • The higher the temperature of the water, the less oxygen can be dissolved in the water • State Water Quality Standard: < 5° F change downstream (approximately 2.8° C)

  22. Oxygen & Temperature Graph

  23. Colorimetry • Most heavy metals either have colored ions, or can be reacted with a reagent that will make the ion colored that can be inserted in a colorimeter and the results compared using a calibration curve

  24. Calibration Curves • The calculators display the output of the colorimeters in absorbance. • These readings then have to be referenced to a standard. • To make the calibration curves, solutions of known amounts of ions are tested and the absorbance recorded. • A graph is then made with the concentration of the ion being tested on the X axis and the absorbance on the Y

  25. Calibration Curves Continued • A best fit line is then put in. • The absorbance of the sample is followed to the line and the concentration is then read off the corresponding X- axis

  26. Calibration Curve Example

  27. Ion Tests • These are done with probes • Some possible ion tests (there are many others) • Ammonium (NH4+) • Calcium (Ca+2) • Chloride (Cl-1) • Nitrates (NO3-1) • Phosphorous (Usually PO4-3) • The output from the probe is recorded on the calculator as a millivolt reading. • These also require a calibration curve to interpret.

  28. Phosphates • Nutrient essential to plant growth, naturally present in low concentrations • Enters water via runoff; present in fertilizers, attached to soil particles, and in organic waste • Can lead to eutrophication = nutrient overload and the system’s response (lots of plant growth) • High P often results in low DO

  29. Phosphate range • Can be in the form of salts of phosphate (Orthophosphate) or organophosphate • There are no state water quality standards for Orthophosphate. However, we do know the Total Phosphate • Typical range (0 to 0.85 mg/L) and • Average (0.05 mg/L). • We generally expect orthophosphate to be less than total phosphate, since orthophosphate is but one component of total phosphate.

  30. Nitrates • Nutrients essential to plant growth • Sewage is main source to rivers and streams • Excessive amounts contribute to eutrophication • High nitrate levels often correspond to high total phosphates and low DO • Typical range for NITRATE (NO3-1) = 0 to 36.08 mg/L • Indiana Average = 12.32 mg/L

  31. Ammonium • Ammonia is a gas • Ammonia reacts with water to form ammonium hydroxide – a weak base • NH3 + H2O  NH4OH NH4+ + OH- • Ammonium is the only positively charged polyatomic ion • Found in a lot of fertilizers as a source of nitrogen for plant growth • Generally measured with a probe and then compared to a calibration curve

  32. Calcium • Often leached out of limestone bedrock • One of the major measures of Hard Water • Measured with a probe and compared to a calibration curve • Tends to be high in southern Indiana & well water, but low in Northern Indiana & surface water

  33. Chlorides • Used as a measure of salinity • Particularly in sea water • A measure of the amount of salts likely to be dissolved in the water. • Most chlorides are soluble • Measured with a probe and checked against a calibration curve

  34. How to Use Ion Probes • Probes are stored in long term bottles with just Distilled Water in sponge • Probes need to be taken out and put in short term storage bottles with High Standard ~ ¾ full @ least 30 minutes, but not > 24 hrs • Plug probe into TI • Turn on TI • Push APPS button • Arrow down to DataMate (or push 4) • Push 1 • Arrow down to Mode & push enter • Push 4

  35. How to Use Ion Probes on TI • Arrow up to Channel 1 • Push 2 the Push 2 again • When voltage reading is stable press enter • Enter 100 • Clean off probe & dry • Put into low standard • When voltage reading is stable press enter • Enter 1 then Press 1 again & Press 1 again • Clean off probe & dry • Put into sample & press 2 • Clean & dry probe • Read concentration in mg/100 ml directly-calculator uses internal calibration curve

  36. Coliform • Biological contamination can be found by using a substrate that will color different colonies of bacteria differently. • This allows the scientist to determine not only how large the bacteria count in the body of water is, but also what types of bacteria are present • These bacteria are not so much a problem by themselves, but indicate that animal waste is being put into the water and the other parts of the waste are the contaminate

  37. Coliscan Easygel • Blue and purple colonies are E.coli • Pink colonies are coliforms • Teal colonies are non-coliforms • Best if incubated at 35oC for 24 hours

  38. E. coli • Typical range for E. coli = 133 to 1,157 colonies/100 mL • Indiana Average = 645 colonies/100mL • State Water Quality Standard for total body contact recreation: • <235 colonies/100 mL (single sample), and • < 125 colonies/100 mL (Geometric mean of 5 samples equally spaced over 30 days)

  39. Chlorophyll a • This requires a sophisticated spectrophotometer • This is one of the tests done on water samples that are provided to IU as part of the Clear Lakes program

  40. Interrelationships

  41. Sources of Pollution • Point Sources • Used to be largest souce of pollution • Most of these sources have already been cleaned up • Individual factories, etc. • Non-Point Sources • Now the largest source of pollution • Grease, oil, gasoline dripping off vehicles • Salt put on roads • Run off from residential fertilizing • Much more difficult to legislate clean up

  42. Programs that empower students • Hoosier River Watch • http://www.in.gov/dnr/nrec/2945.htm • Requires teacher training • Kits are available for checkout and use. • Students enter data directly into a database & the data is used by real scientists • Clean Lakes Program • http://www.indiana.edu/~clp/index.html • Run by IU • Kits are available • Student collected data goes into real database • Other programs out there too

  43. Resources • For activities like the ones we are handing out (grouped by grade and subject): • http://education.ti.com/educationportal/activityexchange/activity_list.do?cid=us • For information on water quality (and all kinds of other natural resource education questions): • http://www.in.gov/dnr/nrec/

  44. Resources • North American Association for Environmental Education • http://eelink.net/pages/Student%20Environmental%20Education%20Sites

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