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IndicatorsWater is seen as “good quality” or “bad
quality” based off of several criteriaThese criteria indicate the health of the
waterIncludes turbidity, pH, dissolved oxygen,
temperature, nitrates, and bio-indicators
Definition: TurbidityTurbidity: measure of the degree to which
water looses its transparency due to the presence of suspended particulates
This is a river with high turbidity
Levels: TurbidityIdeal level: 1 NTU (Nephelometric unit)High level: 5 NTU
Causes: TurbidityCauses of increased turbidity:Increased levels of phytoplankton sediment
from erosion, re-suspended sediments from the bottom (stirred by bottom dwellers), waste discharge, algae growth, and urban runoff
Results: TurbidityResults of high turbidity:High turbidity increases the
absorption of sunlight thus making the water warmer. Warmer water has lower levels of dissolved oxygen causing fish and larvae to die
Definition: pHpH: the acidity of the water (presence of
hydrogen ion)07 is acidic7 is neutral7 14 is basic
Levels: pHSurface Freshwater: 6.0 9.0Swamps: as low as 4.3Salt Water: 8.1 but as low as 7.7
Causes: pHCauses of changes of pH:Natural conditions
(especially in swamps), dumping of waste (batteries) and farm runoff (lime)
Results: pHResults of changes of pH:A change in pH by 2 units results in a water
system having 100 times a difference in acidity
Most aquatic life cannot withstand water outside the optimum pH thus resulting in death
Definition: Dissolved OxygenDissolved Oxygen: the oxygen dissolved in
the water
Levels: Dissolved OxygenAverage level: 9.0 ppm (parts per million)Must be 4-5 ppm to support diverse
population of fish
Causes: Dissolved OxygenCauses of changes in dissolved oxygen:
turbulent actions (waves, rapids), water depth, and plant growth
Results: Dissolved OxygenResults of changes in dissolved oxygen:When DO drops too low, fish dieWhen DO is high, the water actually tastes
better but can corrode water pipes
Definition: TemperatureTemperature: the measure of average kinetic
energy
Levels: TemperatureLow: cannot be tolerated below 32 degrees FHigh: only rough fish can tolerate
temperatures above 97 degrees F
Causes: Temperature
Causes of change in temperature: source of water, time of year, suspended sediment, depth of water, and shade from shoreline vegetation
Results: TemperatureResults of changes in temperature: changes
in temperature can make aquatic life susceptible to disease and at extreme levels can result in death
Definition: Nitrates
Nitrates: compound that contains the nitrogen based polyatomic ion NO3 (Ex: Sodium Nitrate)
Levels: NitratesDrinking Water Max: 10 mg/LFish: Below 90 mg/L seems to have no effect
on warm water fish
Causes: NitratesCauses of nitrates:Fertilizer runoff (both farm
and home), manure pits, leaks in septic systems, animal waste, and rain trapping car exhaust
Results: NitratesResults of presence of nitrates:Nitrates can increase the plant production
and fish population resulting in overcrowdingIf algae increases due to nitrates, the pH
levels decrease killing fishNitrates are converted to nitrites in humans
(can kill children)
Definition: Bio-indicatorsBio-indicators: macroinvertibrates found
living in water (they tend to remain in one place) that are sensitive to pollution
Levels: Bio-indicatorsHigh level of variety: healthy water sourceSmall level of variety: poor water source
(indicator of high levels of pollution)
Causes: Bio-indicators
Causes of changes in bio-indicators:
Pollution that results in changes in pH, temperature, dissolved oxygen, or nitrate levels
Results: Bio-indicatorsResults of few varieties of bio-indicators
present: the lack of a large number of different varieties of bio-indicators is indicative of pollution