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Water Quality Indicators. Physical Indication of Water Pollution. To a great extent, the success or failure of an aquatic ecosystem is determined by water quality. Water Quality Variables. Temperature Dissolved oxygen Total ammonia-nitrogen, NH 3 , NO - 2 Alkalinity & Hardness pH
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Water Quality Indicators Physical Indication of Water Pollution
To a great extent, the success or failure of an aquatic ecosystem is determined by water quality
Water Quality Variables • Temperature • Dissolved oxygen • Total ammonia-nitrogen, NH3, NO-2 • Alkalinity & Hardness • pH • Turbidity • Salinity
Temperature • Normal temperature: 22 degrees CSources: sunlight, thermal pollutionEffects: amount of oxygen that can dissolve, photosynthetic rate, metabolic rates change, sensitivity to toxic wastes • Water temperature fluctuates seasonally, resulting in thermal stratification in deeper water.
Dissolved oxygen and water temperature dissolved oxygen and water temperature usually vary over a 24 hour cycle. Surface dissolved oxygen, mg/L Surface water temperature, °C 31 15 29 10 summer 27 5 25 0 6 a.m. noon 6 p.m. midnight 6 a.m.
High temperature High dissolved oxygen Epilimnion Thermocline Low dissolved oxygen Low temperature Hypolimnion Dissolved oxygen and water temperature Stratification can cause dissolved oxygen and temperature to vary at different depths in the same pond. • In general the minimum DO should be ≥ 60% of saturation or ≥ 5 ppm (mg/L)
Turbidity • Measures the amount of suspended particles in water • Too turbid, then what are the effects? • Temperature rises • Fish may have difficult finding a mate • Clogs fish gills
pH pH is a measure of acidity (hydrogen ion concentration) in water or soil. pH = - log [ H+ ] 2 6 14 0 1 3 4 5 7 8 9 10 11 12 13 neutral acid alkaline
Total Ammonia Nitrogen Total ammonia nitrogen ( TAN ) is a measure of the unionized-ammonia (NH3) and ammonium levels (NH4+) in the water The ratio of ammonia and ammonium varies in an equilibrium determined by pH and water temperature. Ammonia as a % of total ammonia nitrogen
Nitrite/Nitrate NH4++1.5 O2 + Nitrosomonas NO2- + 0.5 O2 + Nitrobacter NO3- nitrite nitrate feces Bacterial decomposition
Alkalinity and Hardness Alkalinity buffers against variations in pH.
Salinity Fresh water is less than 2 g/L Brackish water is 2 g/L to 34 g/L NaCl Sea water is more than 34 g/L