WATER POLLUTION
Chapter 11
INORGANIC NUTRIENTS
• Nitrates and Phosphates are primarily of concern
• Sources:
• Agricultural Fertilizers
• Domestic Sewage
• Livestock Wastes
• Fertilizers that are not absorbed by crop roots is washed into
lakes and streams
CONCENTRATED ANIMAL FEEDING
OPERATION
• 10,000 cattle yield 200 tons of manure daily
• Without proper controls, this waste ends up in waterways
• Hog farms are especially an issue in hurricane prone areas
• Numerous hurricanes in the past 10 years have overwhelmed
detention ponds and carried millions of gallons of hog waste
into polluted waterways
EFFECTS OF INORGANIC NUTRIENTS ON
AQUATIC ECOSYSTEMS
• Nitrogen and Phosphorus
cause aquatic plants to
proliferate, beyond the norm
in the ecosystem, leading to
eutrophication of the water
body
• Eutrophication – The nutrient
enrichment of aquatic
ecosystems
EFFECTS OF INORGANIC NUTRIENTS ON
AQUATIC ECOSYSTEMS (CONT.)
• Eutrophication leads to algal blooms (pea soup), leading to
• Destruction of the aesthetics of lakes and rendering them
unusable for sports and recreation activities
• Give the water a bad taste and odor – a problem for
drinking water
• Reduce dissolved oxygen (DO) in the water, reducing fish
populations
CONTROL OF EUTROPHICATION
• Output Controls
• Upgrading wastewater treatment plants to the tertiary
level.
• Well-built detention basins on feedlots
• Avoid dumping of treated sewage in lakes susceptible
to eutrophication.
• Apply treated wastewater to golf courses,
landscaping, etc.
CONTROL OF EUTROPHICATION (CONT.)
• Input Controls
• Phosphate-free detergents
• Educating citizens/agricultural workers to use less fertilizers
• Erosion control practices
• Site selection – Don’t put hog farms in floodplains
• Planting vegetative barriers between fields and waterways
to trap pollutants
THERMAL POLLUTION
• Defined as an increase in the temperature of water that
adversely affects organisms living in it
• Sources: Industrial Cooling, especially in the generation of
electricity
• Water withdrawn from streams for cooling is heated in the
process. This heated water is discharged into a lake or
stream, creating a thermal plume – a heated body of water
EFFECTS OF THERMAL POLLUTION
• Reduces Dissolved Oxygen (DO) in the
water, causing fish to die.
• Interference with Reproduction – many
fish are instinctively “tuned” to certain
thermal signals that trigger next building,
spawning, and migration.
EFFECTS OF THERMAL POLLUTION (CONT.)
• Increased vulnerability to disease among fish populations
• Direct mortality – some fish simply cannot live in the warmer
temperature.
• Undesirable changes in algal populations
CONTROLLING THERMAL POLLUTION
• Cooling towers – Transfer
heat from the water to the
atmosphere, allowing the
water to cool back down
before it is released back
into the water body
DISEASE-PRODUCING ORGANISMS
• Water contaminated with microorganisms is responsible for
more cases of human illness worldwide than any other
environmental factor.
• Diseases include cholera, typhoid fever, dysentery, polio, and
hepatitis
• Pfiesteria outbreaks – massive fish kills; outbreaks occur in
warm, brackish, when schools of fish are present
CONTROLS TO PROTECT WATER SUPPLIES
• Sewage treatment
• Purification of drinking water
• Safe Drinking Water Act (1974)
• We test for coliform bacteria, which is mostly harmless. High
coliforms is an indicator of levels of potentially harmful
bacteria and viruses.
• If water has more than 2 coliform bacteria per 100 ml, it is
considered unsafe to drink.
TOXIC ORGANIC COMPOUNDS
• Organic compounds are made of primarily carbon and
hydrogen
• Examples include DDT, PCBs, and plasticizers such as BPA
• These toxic compounds were discharged directly to streams
for many years. Some have been injected deep into
underground wells
TOXIC ORGANIC COMPOUNDS (CONT.)
• Groundwater contamination – groundwater serves as
drinking water for 95% of rural households and for 35 of the
largest cities in the U.S
• CERCLA was passed to address the need to clean up
contaminated sites across the country
• RCRA was passed to address hazardous waste as well as nonhazardous waste
EROSION CONTROL
GROUND WATER CONTAMINATION
HEAVY METALS
• Highly toxic elements such as lead and mercury.
• Sources
• Abandoned Mines, mine tailings
• Air emissions from coal-fired power plants
• Metal processing plants
• These are not broken down – persist in the environment and in our bodies
• Poisons
• Upper-level organisms, including people, have high mercury
concentrations in cell tissues.
MERCURY IN FISH