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Pollution
Chapter 20
 Water pollution: any change in water quality that can cause
harm to living organisms or make the water unfit for human
use (drinking, agriculture)
 Chemicals, heat, bacteria, etc
 Air pollution: presence of chemicals in the atmosphere in
high concentrations enough to harm organisms, ecosystems,
or human-made materials, or to alter climate
 From natural and human sources
Types of Pollution
 Point source pollution
 Discharge pollutants into specific locations through drain pipes,
ditches, or sewer lines
 Factories, mines, oil spills
 Easy to identify and monitor
 Non-point source pollution
 Broad and diffuse areas from which pollutants enter water or air
 Runoff from cropland, feedlots, streets, lawns, golf courses
 Difficult to identify and control
Sources of Water Pollution
 Agricultural Activities
 Leading cause of water pollution
 Sediment, fertilizer, pesticides, bacteria
 Industrial Activities
 Release organic and inorganic compounds
 Energy Sources
 Coal ash, fracking
 Mining
 Erosion and runoff of toxic chemicals
 Human Sources
 Garbage--Plastic polymers release chemicals into water
 Nurdles!
 Human wastewater (Sewage and gray water)
 Runoff from roadways and parking lots (gasoline and oil)
Water Pollution Legislation
 Clean Water Act 1972
 Eliminate the release of high amounts of toxic chemicals into surface water
 Finance wastewater management
 Safe Drinking Water Act 1974
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Ensures safe drinking water for the public
EPA sets standards for drinking water quality
Applies to public water systems…not private wells
Bottled water regulated by the FDA under the Food, Drug and Cosmetic
Act
 Groundwater contamination is addressed with…
 Resource Conservation and Recovery Act (Solid and Hazardous
Waste disposal)
 Superfund (CERCLA) Act (contaminated sites)
List of Water Pollutants
 Fill in the table of common water pollutants with their source,
specific examples, environmental impacts (effects), and potential
solutions (ways to decrease)
 Infection agents (pathogens)—give specific species/disease
 Oxygen-demanding wastes
 Inorganic chemicals
 Organic chemicals
 Plant nutrients
 Sediments
 Heavy metals
 Thermal
Pollution in Lakes and Rivers
 Streams have natural cleansing cycle…if not overloaded with a specific
contaminant
 Developed countries
 Laws enacted to protect from point source pollution and sewage
 Limited drinking water contamination
 Developing countries
 Serious and growing problem due to less infrastructure and regulation, especially
with sewage
 Lakes less effective at diluting pollutants, layers in lake that don’t mix
regularly
 Eutrophication- natural nutrient enrichment
 Cultural eutrophication- human activities increase the input of plant
nutrients (nitrates and phosphates)
 Reduced productivity and increased algal growth
Groundwater Pollution
 Common pollutants include:
 Fertilizer (nitrates), pesticides,
gasoline, oil, and other solvents
 Serious threat to human health,
contaminants fill in porous rock
layers in aquifers
 Difficult and costly to
remove/cleanup pollutants
 Can’t cleanse itself very quickly;
dilute or disperse contaminants
 Cold temps, low bacteria and low
dissolved oxygen
 Prevention only way to deal with
this pollution effectively!
 Over 1 billion people lack
access to clean drinking water
 Developed countries have
drinking water standards (Safe
Drinking Water Act)
 Water treated before made
available to public
 Recycling wastewater (CA and
TX)—expensive!
 Developing countries can use
simple technology to purify
water
 Sunlight, Lifestraws, and
powders
Ocean Pollution
 Coastlines most polluted (where everyone lives)
 Untreated sewage, garbage, agricultural runoff
 Increased nitrates and phosphates cause toxic algal blooms (red tides),
which harm marine organisms and humans
 Oil Spills—also runoff from roads and parking lots
 Creates oxygen depleted zones (dead zones)
 Hypoxic (low oxygen), results in high bacteria levels
 Garbage litters ocean (mostly plastic)
 Atlantic and Pacific Garbage Patches
 Best prevention is to reduce flow of pollution into ocean
Water Quality Testing
 Fecal Coliforms
 This nasty stuff is a certain bacteria that propagate in the digestive tracts of humans and
animals. They coexist with other bacteria so they are often used as indicators of possible
pathogenic contamination. There are many ways fecal coliform can enter a waterway
such as animal waste, untreated sewage, combined sewage overflow, and septic tanks.
 Dissolved Oxygen
 This test is the most important of the nine water quality tests to measure water's ability
to support plants and animals. There are many different factors that affect the amount of
dissolved oxygen in water, the main one being temperature. As temperature rises, less
gas will dissolve.
 Turbidity
 Turbidity measures water clarity, which allows sunlight to penetrate to a greater depth.
The main sources of turbidity are erosion, living organisms, and those from human
endeavors
 pH
 The pH of water is important to aquatic life. If the PH falls below 4 or above 9
everything is dead.
 Total Solids
 Total solids measures both dissolved and suspended solids. There are six major types of
total solids; silt, clay, soil runoff, plankton, industrial waste, and sewage
 Temperature
 Temperature is a very important part of a river's ecology. There are many
natural and human factors that can affect a river's temperature. Human
factors include industry, development, and dams. If the difference is greater
than 2 degrees Celsius, then there is thermal pollution. To find flow rate you
use a buoyant object, we used an orange, and float it down the river
 Nitrates
 Nitrogen is necessary for plant and animal life. Water is tested for nitrates to
monitor and control eutrophication , which causes more plant growth and
decay
 Phosphates
 Phosphates is a nutrient needed in growth. The phosphate ion is found in
shells, bones, and in animal teeth. By removing phosphorous from sewage
the amount of phosphate ions in the water will be lowered.
 Biological oxygen demand
 BOD is a measure of oxygen removed from an aquatic environment by
aerobic microorganisms. It measures levels of organic pollution in lakes and
streams
 Alkalinity
 Alkalinity is a measure of the capacity of water to neutralize acids (see pH
description). Without this acid-neutralizing capacity, any acid added to a
stream would cause an immediate change in the pH. Measuring alkalinity is
important in determining a stream's ability to neutralize acidic pollution
from rainfall or wastewater. It's one of the best measures of the sensitivity of
the stream to acid inputs.
 Carbon Dioxide
 When the oxygen concentration in waters containing organic matter is
reduced, the carbon dioxide concentration rises. The rise in carbon dioxide
makes it more difficult for fish to use the limited amount of oxygen present.
To take on fresh oxygen, fish must first discharge the carbon dioxide in their
blood streams and this is a much slower process when there are high
concentration of carbon dioxide in the water itself.
 Chlorine
 Used as a disinfectant in drinking water; Chlorine causes environmental
harm at low levels. Chlorine is especially harmful to organisms living in
water and in soil..but only in high doses.
Sewage/Wastewater Treatment
 Septic tank: household sewage and wastewater is pumped into a
holding tank; grease/oil rise to the top, solids sink to be
decomposed by bacteria
 Some wastewater is leached out into drainfield to be decomposed by
soil and bacteria; pumped to remove material periodically
 Wastewater Treatment Facilities: raw sewage is treated in two
steps to remove particulates
 Primary: physical treatment/removal of solids
 Secondary: biological treatment/removal of solids
 Before discharge…the water is treated to remove any remaining
disease-carrying bacteria
 https://www.youtube.com/watch?v=whjEikBiOFo