water quality. how are physical and biological factors used to determine water quality? – how do...
TRANSCRIPT
Water Quality
Water Quality
• How are physical and biological factors used to determine water quality?–How do we know if water is safe to drink?
–How do we know if water is safe for aquatic organisms?
Water Quality Indicators
• Temperature• Dissolved Oxygen• pH• Nitrates and Phosphates• Turbidity• Bio-Indicators
TemperatureCauses of Temperature Change:• Color of water:
– Dark colored water or dark muddy bottoms absorb more heat.
• Water depth: – Deep waters usually are colder than shallow waters
simply because they require more time to warm up.
• Shade: – Shoreline vegetation and trees that cover the water
prevent water from heating to fast.
• Location and time of year
TemperatureEffects of Temperature Change:• Rapid temperature change and temperature
extremes can stress aquatic organisms.• Fish and most aquatic organisms are cold-
blooded. – Their metabolism increases as the water warms
and decreases as it cools.
• Each species has its own optimum water temperature. – If the water temperature shifts too far from the
optimum, the organism suffers.
TemperatureEffects of Temperature Change:• Temperature affects the oxygen-
carrying capacity of water.–As the water warms, the amount of
dissolved oxygen decreases.– If high water temperatures are
combined with low dissolved oxygen levels, the toxicity is increased.
Dissolved Oxygen• Dissolved Oxygen is oxygen that is
dissolved in water. It gets there by –diffusion from the surrounding air–aeration of water that has tumbled over
falls and rapids–a waste product of photosynthesis.
• Fish and aquatic animals cannot split oxygen from water (H2O) or other oxygen-containing compounds.
Dissolved OxygenCauses for Lack of Dissolved Oxygen:• Warm water holds less oxygen• Overpopulation—too many
organisms using Dissolved Oxygen• Over-fertilization of water plants by
run-off from farm fields containing phosphates and nitrates (the ingredients in fertilizers).
Dissolved OxygenEffects of Dissolved Oxygen• Dissolved Oxygen below 3.0 parts
per million, can cause the most versatile fish to die.
• High Dissolved Oxygen in a community water supply makes drinking water taste better. –But speeds up corrosion in water pipes.
pH• pH is the measure of the hydrogen ion
(H+) concentration. • The pH scale is zero to 14.
– Pure water has a equal number of H+ and OH- ions, which makes it neutral 7.
• Most aquatic organisms exist within a pH range of 5.5 to 9.5.
Acidic BasicNormal Levels
pHCauses of change in pH:• Lakes or ponds
–age and the chemicals discharged by communities and industries.
Effects of pH:• More acidic water can kill certain
aquatic organisms.–A change of .3 units a day can put a fish
into shock
Phosphates
• The element phosphorus is necessary for plant and animal growth. –Phosphate concentrations in clean water is generally low.
Phosphates
• Causes of high Phosphorus–Fertilizer from runoff–Detergents–Natural mineral deposits.
PhosphatesEffects of high amounts of Phosphates:
• Can over stimulate the growth of aquatic plants and algae.
–This will cause high Dissolved Oxygen consumption and death to fish and many aquatic organisms.
Nitrates
• Nitrates are a form of nitrogen and is a primary plant nutrient.
• Excess nitrate causes algal blooms that reduce water quality.
Nitrates
Causes of increased Nitrates:• Waste water• Fertilizer from runoff• Discharge from car exhaust
NitratesEffects of increased Nitrogen:• Stimulate the growth of plankton and water
weeds that provide food for fish. – May increase the fish population. – If algae grow too wildly, oxygen levels will be
reduced and fish will die.
• Nitrates can be reduced to toxic nitrites in the human intestine, and many babies have been seriously poisoned by well water containing high levels of nitrate-nitrogen.
Turbidity
• Turbidity refers to water clarity.• Sediments suspended and/or
dissolved in the water decrease the amount of light that is able to pass through.
Turbidity
Causes• Soil erosion of agricultural
lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction.
• Plankton
TurbidityEffects:• Interference with sunlight penetration. • Large amounts of suspended matter may clog
the gills of fish and shellfish and kill them directly.
• Suspended particles may provide a place for harmful microorganisms to lodge and reproduce.
• Difficulty finding food. – May make it easier for fish to hide from
predators.
Turbidity• Turbidity is the clarity of water or how much dirt is in
the water.• Low Turbidity water is clear, less dirt• High Turbidity water is polluted, more dirt• Dirt• #1 cause of pollution• Decreases oxygen• Contents blocks sunlight from reaching plants• Rises temperatures causing Thermal Pollution, this
causes water to expand and lose oxygen• Gets in gills of fish • Crushes fish eggs
Bioindicators• Bioindicators are living organisms
that provide information about the health of an ecosystem. – Lichens, which are plants that live on trees
rocks and soil, are very sensitive to toxins in the air.
– Algae blooms are often used to indicate large increases of nitrates and phosphates in lakes and rivers.