Transcript on WQI
Water Pollution: Contaminants and Testing Procedures S What is Water Pollution? S Water pollution - any change in water quality that harms humans or other living organisms or makes water unsuitable for desired uses. Application: “The Mistake by the River” Cuyahoga River in the Fall ©Tom Jones http://csudigitalhumanities.org/ex hibits/items/show/1328 A Burning River? The Plain Dealer File http://oceanservice.noaa.gov/education/ kits/pollution/02history.html http://www.youtube.com/watch?v=tZA9OX2joUc&feature=r elated What are the sources of water pollution? S Point Sources S Can be traced back to one particular origin S S Industrial Plants (Power, Chemical, Waste Treatment) Drain pipes, Sewer Lines, Underground Mines S Nonpoint Sources S Tend to be widespread with many regions contributing to the water pollution. S S Agricultural Runoff Stormwater Runoff (Roads and Parking Lots) Fig. 11-23, p. 260 Types of Contaminants S Pathogens – Wastes from Humans and Animals S Plant Nutrients – Nitrates & Phosphates S Organics – Oil, Gasoline, Plastics, & Pesticides S Inorganics – Salt, Metal Compounds S Sediment – Total Suspended Solids S Heavy Metals S Thermal Most Commonly Tested Parameters S Temperature S pH S Nitrates S Phosphates S Dissolved Oxygen S Turbidity S Specific Conductivity S Total Dissolved Solids S Total Suspended Solids Water Quality Index Water Quality Index (WQI) is a measure of how polluted a body of water actually is. It can take many different parameters into consideration. (6 parameters are typically used to calculate WQI) Utilizes a weighting factor to differentiate between important parameters and less-important parameters. Q-Values are numbers that are given in a table and correlate to the level of each parameter to characterize each on a scale of 0-100 (100 being best) Water Quality Index Q-Value Weight Factor 0.17 Dissolved Oxygen Test Result 103.1% Sat. Fecal Coliform 2 / 100mL 0.16 pH 7.59 0.11 BOD (5-day) 1.75 mg/l 0.11 Temperature 1°C 0.10 Phosphates .45 mg/l 0.10 Nitrates .6 mg/l 0.10 Turbidity 50 cm 0.08 Total WQI Subtotal Water Quality Index Test Results Q-Value Q-Value X Weighting Factor Add all Subtotals Water Quality Index Parameter Tested Value Dissolved Oxygen 90 0.3 Nitrate 1.75 0.2 Phosphate 0.3 0.2 pH 6.70 0.3 Totals Q-Value Weighting Calculation Factor Water Quality Index Dissolved Oxygen: % saturation = 90 1. In the DO column find the value equal to 90. 2. Write down the Q-Value to the right of that number (Q-value = 95). Water Quality Index Parameter Tested Value Q-Value Weighting Factor Calculation Dissolved Oxygen 90 95 0.3 95 X 0.3 = 28.5 Nitrate 1.75 0.2 Phosphate 0.3 0.2 pH 6.70 0.3 Totals Water Quality Index Nitrate: 1.75 mg/L 1. In the Nitrate-N Column find the values closest to 1.75. This number falls between 1.5 and 2 in this column 2. Since there is no value matching exactly to 1.75, estimate the Q-value between 92 and 90 (Q-value = 91). Water Quality Index Parameter Tested Value Q-Value Weighting Factor Calculation Dissolved Oxygen 90 95 0.3 28.5 Nitrate 1.75 91 0.2 91 X 0.2 = 18.2 Phosphate 0.3 0.2 pH 6.70 0.3 Totals Water Quality Index Phosphate: 0.3 mg/L Water Quality Index Phosphate: 0.3 mg/L 1. In the Total Phosphate column find the value equal to 0.3 (similar to the dissolved oxygen). 2. Write down the Q-Value to the right of that number (Q-value = 90). Water Quality Index Parameter Tested Value Q-Value Weighting Factor Calculation Dissolved Oxygen 90 95 0.3 28.5 Nitrate 1.75 91 0.2 18.2 Phosphate 0.3 90 0.2 90 X 0.2 = 18.0 pH 6.70 Totals 0.3 Water Quality Index pH: 6.70 1. In the pH column find the values closest to 6.70. This number falls between 6 and 7. 2. Since there is no value matching exactly to 6.70, estimate the Q-value between 55 and 90 (Q-value = 81). Water Quality Index pH 6 Q-value 55 7 90 Water Quality Index pH 6 Q-value 55 6.5 7 72.5 90 (55+90) / 2 = 72.5 Water Quality Index pH 6 Q-value 55 6.5 6.75 7 72.5 81.25 90 (72.5+90) / 2 = 81.25 Water Quality Index Parameter Tested Value Q-Value Weighting Factor Calculation Dissolved Oxygen 90 95 0.3 28.5 Nitrate 1.75 91 0.2 18.2 Phosphate 0.3 90 0.2 18.0 pH 6.70 81 0.3 81 X 0.3 = 24.3 Totals Water Quality Index Parameter Tested Value Q-Value Weighting Factor Calculation Dissolved Oxygen 90 95 0.3 28.5 Nitrate 1.75 91 0.2 18.2 Phosphate 0.3 90 0.2 18.0 pH 6.70 81 0.3 24.3 Totals 28.5 + 18.2 + 18.0 + 24.3 = 89.0 Water Quality Index Water Quality Percentages Excellent 90-100% Good 70-90% Medium 50-70% Bad 25-50% Very Bad 0-25%