Transcript Introduction to Water Quality Monitoring

Urban Water Quality
Water Quality
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Pollution - any departure from
“purity”
– What is “purity”?
– Characteristics of water
– Is drinking water “pure”?
Water Quality
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Pure Water - in the context of
water pollution, a state of water in
which no substance is present in
sufficient concentration to prevent
the water from being used for the
purposes thought of as “normal”
Water Quality
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“Normal” uses of water?
– Recreation
– Public water supply
– Aquatic habitats
– Agriculture
– Industry
Water Quality
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Water Pollutant - any substance
that prevents the “normal” use of
water
– “Normal” implies a value judgement
and depends on the particular use
Water Quality
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Water Quality - the physical and
chemical characteristics of water
– Unrelated to the particular use in that
no value judgement is assigned
Water Quality - Classification
of Water Pollutants
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Signs of water pollution?
– Bad tasting drinking water
– Masses of aquatic weeds
– Disgusting odors
– Decreasing fish populations
– Floating oil and raw sewage
Water Quality - Classification
of Water Pollutants
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Classification of water pollutants
– Oxygen-demanding wastes (ODW)
– Pathogenic organisms
– Plant nutrients
– Synthetic organic compounds (SOCs)
– Oil
– Sediments
– Heat
Water Quality - Classification
of Water Pollutants
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Oxygen-Demanding Wastes (ODW)
– Dissolved Oxygen
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Aquatic organisms require oxygen for
cellular respiration
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Dissolved oxygen (DO) is often a limiting
factor for survival of aquatic organisms
Water Quality - Classification
of Water Pollutants
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ODW
– Dissolved Oxygen
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Factors that control DO levels:
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Water temperature
Elevation above sea level
Degree of turbulence
Stream channel geometry
Density of aquatic plants
Water Quality - Classification
of Water Pollutants
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ODW
– Dissolved Oxygen
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Water Temperature
– DO decreases with increasing water
temperature
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Elevation Above Sea Level
– DO decreases with increasing elevation
Water Quality - Classification
of Water Pollutants
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ODW
– Dissolved Oxygen
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Turbulence
– DO increases with increasing turbulence
caused by waterfalls, rapids, etc
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Stream Channel Geometry
– Wide,shallow channel has greater DO than
narrow, deep channel
Water Quality - Classification
of Water Pollutants
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ODW
– Organic substances that cause
depletion or removal of DO
– Food source for aquatic bacteria
– DO is removed as bacteria feed on
ODW
Water Quality - Classification
of Water Pollutants
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ODW
– Sources of ODW
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Sewage
Paper mills
Food processing
Slaughterhouses
Water Quality - Classification
of Water Pollutants
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ODW
– Biochemical Oxygen Demand - the
amount of dissolved oxygen that
bacteria require to decompose ODW
in a given volume of water
Water Quality - Classification
of Water Pollutants
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ODW
– Biochemical Oxygen Demand (BOD)
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Measurement
– 5-day test
– Incubation at 20 degrees C
– BOD = DO (day 0) - DO (day 5)
Water Quality - Classification
of Water Pollutants
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ODW
– Biochemical Oxygen Demand (BOD)
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Characteristic BOD Levels
– Untreated Sewage
– Feedlots
– Pure Water
100-400 mg/L
100-10,000 mg/L
1 mg/L
Water Quality - Classification
of Water Pollutants
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ODW
– Environmental Impacts of low DO
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Disappearance of plant and animal life
Shift from aerobic to anaerobic conditions
“Oxygen Sag”
Water Quality - Classification
of Water Pollutants
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Pathogenic Organisms
– Types of pathogens:
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Viruses
Bacteria
Protozoa (unicellular)
Parasitic worms
Water Quality - Classification
of Water Pollutants
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Pathogenic Organisms
– Diseases caused by water-borne
pathogens:
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Amoebic Dysentery
Bacterial Dysentery
Typhoid fever
Cholera
Hepatitis
Schistosomiasis
Water Quality - Classification
of Water Pollutants
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Pathogenic Organisms
– Sources of body wastes:
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Malfunctioning septic tanks, cesspools
Untreated sewage
Waste discharges from boats and ships
Meat processing plants
Swimmers and hikers
Water Quality - Classification
of Water Pollutants
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Pathogenic Organisms
– Testing for pathogenic organisms
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Coliform bacteria
– Live in large intestines of warm-blooded animals
(even Uncle Monty) and absorb nutrients from their
surroundings
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Plants require 15-20 nutrients for
growth:
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Carbon
Nitrogen
Phosphorus
Potassium
Sulfur
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Nitrogen and phosphorus are limiting
nutrients for plant growth
– Eutrophication - the natural enrichment
of water with plant nutrients
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Eutrophic Ecosystem - ecosystems that are
relatively high in fertility and biological
productivity
– Oligotrophic Ecosystem - ecosystems that
are relatively low in fertility and biological
productivity
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Cultural Eutrophication - accelerated
eutrophication caused by human
activities
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Signs and effects of cultural
eutrophication:
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Dense growth of rooted plants
Increased growth of blue-green algae
Increased populations of trash fish
Foamy layers on surface of water
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Sources of nutrients responsible for
cultural cultural eutrophication:
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Domestic Sewage
Urban Runoff
Industrial Sources
Agricultural Sources
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Management practices to minimize
cultural eutrophication:
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Two types of water pollution sources in a
watershed:
– Point Source
– Non-Point Source Pollution
Water Quality - Classification
of Water Pollutants
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Plant Nutrients
– Management practices to minimize
cultural eutrophication:
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Nutrient management
– Determine point and nonpoint sources of nutrients
and the size of each source
– On-site treatment of nutrients
– Rate and timing of nutrient application
Water Quality - Classification
of Water Pollutants
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Synthetic Organic Compounds (SOCs)
– Examples:
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Fuels
Plastics
Pesticides
Fertilizers
Food additives
Pharmaceuticals
Water Quality - Classification
of Water Pollutants
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Synthetic Organic Compounds (SOCs)
– Pesticides
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Environmental Impacts
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Bioaccumulation
Interference with reproduction
Birth Defects
Reduced biodiversity and productivity
Tumors and convulsions
Water Quality - Classification
of Water Pollutants
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Synthetic Organic Compounds (SOCs)
– Oil (Hydrocarbons)
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Sources
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Impervious surfaces
Oil leaks
Auto emissions
Improper disposal of waste oil
Water Quality - Classification
of Water Pollutants
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Synthetic Organic Compounds (SOCs)
– Oil (Hydrocarbons)
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Environmental Impacts
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Degrade appearance of water surfaces
Limit air exchange between atmosphere and water
Lowered DO levels
Increased BOD
Impair habitat
Reduced biodiversity
Death
Water Quality - Classification
of Water Pollutants
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Sediment
– Most common of the nonpoint source
pollutants
– Sediment load in waterways increases
with increasing urbanization and landuse
intensity
Water Quality - Classification
of Water Pollutants
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Sediment
– Factors controlling sediment loss:
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Chemical and physical characteristics of the
soil
Slope steepness
Type and density of vegetation cover
Rainfall
Water Quality - Classification
of Water Pollutants
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Sediment
– Environmental Impacts
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Filling of channels and harbors with sediment
Decreased biodiversity of aquatic animals
Increased turbidity
Water Quality - Classification
of Water Pollutants
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Heat (Thermal Pollution)
– Sources
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Cooling water in industrial processes
Natural heating by sunlight
– Environmental Impacts
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Decreased DO
Increased rates of chemical reactions
False temperature cues to aquatic life
Death to aquatic organisms
Water Quality - Classification
of Water Pollutants
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Heat (Thermal Pollution)
– Environmental Impacts
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Decreased DO
– “Thermal Blanket”
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Warm water is less dense than cold water
Warm layer forms “blanket” over cooler, more dense
water
Warm water cannot dissolve as much atmospheric
oxygen as cooler water
Rate of exchange of oxygen between warm water
and cooler water is very slow
Cooler water is “atmospherically unreplenished”
Death to aquatic organisms
Water Quality - Classification
of Water Pollutants
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Heat (Thermal Pollution)
– Environmental Impacts
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Increased rates of chemical reactions
– The rate of any chemical reactions approximately
doubles with every 10C increase in temperature
– In thermally polluted waters, fish require more DO
because of increased respiration rates
– Increased respiration occurs in response to higher
water temperature
Water Quality - Classification
of Water Pollutants
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Heat (Thermal Pollution)
– Environmental Impacts
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False temperature cues given to aquatic life
– Fish spawn and migrate in response to temperature
cues
– Optimum temperature range for fish species