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Graphing Water Quality Data

    Directions for Graphing Water      Quality
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Pollutant and Water Quality     Information

     Dissolved Oxygen
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     Methyl-t-betyl Ether
     Turbidity & Sedimentation

Water Testing
     Fecal Coliform
     Dissolved Oxygen
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How to test for Dissolved Oxygen

Note: When completing Dissolved Oxygen tests make sure that no extra oxygen or air bubbles are contained in the sample

According to the state of North Carolina the acceptable levels of dissolved oxygen may not be less than 6.0 mg/l for trout waters; 5.0 mg/l for non-trout waters and with a minimum instantaneous value of not less than 4.0 mg/l.

• In a clean 300 mL glass stoppered Biological Oxygen Demand (BOD) bottle collect your sample
• Add one manganous sulfate powder pillow and one alkaline Iodide-Azide Reagent Powder Pillow to the sample
• Immediately insert the stopper so that no air is trapped in the bottle and adds more DO
• Invert the bottle several times in order to mix the sample
• Wait until the stuff inside has settled to the bottom
• You want to then invert the bottom again until all of the sediment is at the bottom and the top half of the bottle is clear
• Add one sulfuric acid powder pillow after replacing the stopper
• Replace the stopper carefully and immediately after adding the powder
• Mix the bottle again by inverting it several times
• Measure out a 200 mL sample of the prepared sample
• Pour the 200 mL sample into a 250 mL Erlenmeyer flask
• With 0.025 N Sodium Thiosulfate Solution fill a 25 mL burette to the zero mark
• Then with the sodium thiosulfate solution titrate the prepared sample until the solution is a pale yellow color
• Add the starch indicator solution in two 1-mL dropps
• Then swirl the flask to mix the solution until a dark blue color develops
• Titrate until the solution becomes colorless
• Calculate the amount of Dissolved Oxygen with the formula
? mL of Titrant Used = mg/L dissolved Oxygen present

Items Needed for this experiment are listed below and are from the HACH company with the description of what is needed followed by the Catalog number.

Description (Catalog Number )

Required Reagents
• Alkaline Iodide-Azide Reagent Powder Pillows 1072-66
• Manganous Sulfate Powder Pillows. 1071-66
• Sodium Thiosulfate Standard (titrant), 0.025 N 24093-53
• Starch Indicator Solution. 349-32
• Sulfamic Acid Powder Pillows. 1073-99

Required Apparatus
• Bottle, glass-stoppered, BOD, 300-mL 621-00
• Buret Clamp, double .. 328-00
• Buret, Class A, 25-mL 26365-40
• Clippers, for opening powder pillows . 968-00
• Cylinder, graduated, 250-mL. 508-46
• Flask, Erlenmeyer, 250-mL 505-46
• Support Stand 563-00

APHA Required Reagents
• Alkaline Iodide-Azide Reagent Solution 277-49
• Manganous Sulfate Solution 275-49
• Sodium Thiosulfate Standard Solution, 0.025 N 352-53
• Starch Indicator Solution 349-32
• Sulfuric Acid, ACS 979-49

APHA Required Apparatus
• Buret Clamp, double 328-00
• Buret, Class A, 25-mL 26365-40
• Support Stand 563-00
• Pipet, 1-mL 14515-35
• Pipet Filler, Safety bulb 14651-00

Required Standards
• Iodate-Iodide Standard Solution, 0.00125 N 401-49