What is Water Pollution?
Chapter 20 APES 2007
Water Pollution defined:
A Physical, Chemical, or Biological Change in water quality that: Adversely affects living organisms Or Makes water unsuitable for desired uses
Natural vs. Unnatural Sources
There are natural sources.
We will focus on Human caused issues.
Two types of water pollution Sources:
Point Source Nonpoint Source
Point Source Pollution
Discharge from a specific location, YOU CAN point at it and say, look, pollution!
Examples of Point Source Pollution
Drain pipes Ditches Sewer outfalls Pros: Easy to monitor and regulate Possible to treat before entering the environment
Nonpoint Source Pollution
Sources are scattered or diffuse, having so specific location.
Examples of Nonpoint Source Pollution
Runoff from: farm fields Golf courses Gardens Construction sites Logging areas Roads, streets, parking lots Atmospheric deposition of contaminants! Contaminants carried by wind and rain!
HIGHLY EPISODIC: tough to regulate!
Types and Effects of Water Pollution
We will group these pollutants into two categories: Those that cause health problems Those that cause ecosystem disruption Let’s tackle each group separately. See chart page 450 for some ideas!
Those that cause health problems:
Infectious agents Organic chemicals Inorganic chemicals Radioactive materials
Infectious agents
Pathogenic organisms There are three types: Bacteria (test for coliform bacteria) Viruses Protists These are found in excrement.
Bad Stuff:
People suffer and die from horrible diseases that could be prevented by good sanitation practices.
Organic chemicals
Pesticides, plastics, detergents, oil Sources: Runoff from farms and households industrial and household chemicals not disposed of properly
Bad Stuff:
Birth defects Genetic disorders Cancer Chemicals persist, don’t break down Contaminate ground and surface water sources for human consumption
Inorganic chemicals
Acids, Caustics, Metals, salts These can be released naturally through weathering and erosion. Human activities can speed that up: Mining, processing, using, and discarding minerals.
Bad Stuff:
Metals Mental health issues, brain damage
Salts
Radioactive materials
Uranium, thorium, cesium, iodine, radon
Sources: Mining and processing of ores Power plants Weapons production Natural sources
Bad Stuff:
DNA and RNA gets modified….
Those that cause ecosystem disruption:
Sediment Plant nutrients Oxygen demanding wastes Thermal
Sediment
Soil and silt resulting from erosion
Land erodes. This just happens. This can be accelerated by activities of humans: vehicle use, road building, mining, foliage removal…
Bad Stuff:
These sediments: Fill lakes and reservoirs Obstruct shipping channels Clogs hydroelectric turbines Makes purifying of drinking water more costly Smother gravel beds where insects and fish lay eggs Sunlight is blocked: photosynthesis drops, oxygen levels decline Murky water is less attractive.
Plant nutrients
Nitrates & Phosphates (fertilizers and excretion) Ammonium (excretion)
Sources: Sewage, fertilizers, manure
Bad Stuff:
Define oligotrophic lakes and eutrophic lakes Cultural eutrophication: When biological productivity and ecosystem succession is caused by human activities. This causes algae bloom, fish die, bacteria take over, and the area dies.
Oxygen demanding wastes
Animal manure and plant residues
Sources: Sewage, agricultural runoff, paper mills, and food processing
Bad Stuff:
BOD: Biological Oxygen Demand DO: Dissolved Oxygen Several factors determine the BOD of an area: Volume Flow Temperature Aeration Oxygen sag:
Thermal
Heat energy changes the temperature of the water.
Power plants, industrial cooling
Bad Stuff:
Water quality drops Plants and animal balance changes As temp goes up, DO drops
What to do: Make artificial ponds to cool the water down before discharge.