Chapter 21 Water Pollution
21.1
Intro
Not a new problem
In 19th century England, France, US, and Germany dumped garbage to waterways.
Rivers all over the world became contaminated causing cholera, typhoid, and dysentery to
become common.
90,000 killed from typhoid in 1885 Chicago
Many also killed from Cholera in 1892 in Hamburg Germany
Thanks to Robert Koch, people began to realize contaminated water was a serious issue.
Practice of dumping into water ways was banned from US and European countries.
Barges were used to dump water farther out to sea, but it didn’t work because it is still a
problem.
Garbage dumped in ocean doesn’t disappear, but it drifts back to shore.
Sewage
Sewage: Water that contains organic wastes from humans and industry.
Comes from toilets, sinks, dishwashers, washing machines, and industrial equipment
In US it is usually treated before it is dumped.
In US country dumps about 8.9 trillion L of sewage into the ocean each year; some isn’t treated
before it is dumped.
A lot of waste is from factories that contain toxic chemicals and metals.
Sewer System: interconnected pipes underground used in urban areas
Modern Sewer Systems are connected to Sewage Treatment Plants.
Sewage treatment plant: facility that processes raw sewage before sewage is returned to
surface water systems.
The Sewage Treatment Plant
Sludge: Solid Materials
1st: Bar Screen- Raw Sewage passes through screens that filter out plastics, fabrics, and metallic
objects
2nd: Grit Chamber- Lets Grit settle to preserve machinery pumps.
3rd: Settling Tank- allows sludge to settle to separate from water
4th: Clorination- Used to sanitize and deodorize the treated water, this water then leads to the
surface water
Sludge from the Settling Tank drains to a Sludge Digester to promote decay that leads into a
sludge drying bed.
The dried sludge are used as fertilizers or they are disposed in landfills.
This process filters out most but not all pollutants
Many countries don’t have effective Sewage treatments
Pathogens
Pathogens: Parasites, bacteria, and viruses that cause diseases in living things.
Most enter water systems through sewage or animal waste.
Pathogens carried by water result in more human illness and death than any other
environmental factor
Typhoid and Cholera are examples of bacterial diseases spread by water
Schistosomiasis is a disease caused by microscopic worms. They enter through skin for people
that walk in that contaminated water. Worms attack liver, urinary bladder, and intestines.
Malaria is a disease caused by a protozoan. Usually transmitted through humans by bite of
mosquito. Not transmitted by contact with water, but water is breeding ground of bugs that
transmit disease. More than 800 million are infected and 1 million die.
Protozoan: microscopic, animal like protists.
Types of Water Pollution
Sewage is the 2nd largest source of pollution
Largest is runoff from farming because Pesticides, Fertilizers and plant/animal wastes end up in
water.
Pathogens, Nutrients, and Sediments are most common pollutants
Toxic is also dangerous, and Plastic is a major pollutant
Acids and Radioactivity are also pollutants
These pollutants affect aquatic ecosystems and are a threat to human health.
21.2
Toxic Chemicals: Elements and Compounds that are directly harmful to living things. Either
organic or inorganic. Inorganic are compounds that lack carbon. Organic contain carbon and
are derived from organisms.
Inorganic Chemicals
Include acids, salts, heavy metals, and plant nutrients.
Heavy metal: a metallic element with a high mass number.
Some examples are mercury lead, cadmium, nickel, and chromium.
Plant Nutrients: molecules that do not contain carbon yet are needed for plant grow.
Phosphates and nitrates are important.
Acids and heavy metals enter groundwater and surface water from seepage, runoff, and direct
discharge.
Heavy metals are poisonous and if they are ingested they can cause liver, brain, and kidney
damage, coma, or death.
Mercury poisoning occurred 1950s in Minamata.
The first sign was of poisoning was strange animal behavior and the doctors discovered that the
reasons for the act was mercury poisoning. The mercury came from plastics factory that
discharged mercury wastes into waters of Minamata Bay. It contaminated the fish which the
people ate. 8000 people suffered paralysis and brain damage.
Organic Chemicals
Can be pollutants and are usually made from living things
Gas, Oil, Plastics, Pesticides, Fertilizers, Solvents, and Wood Preservatives.
Runoff contains lots of Organic Chemicals
Crude Oil is one of the most common and dangerous organic pollutant. Usually enters water
because of oil spills.
Oil Spills= ORGANIC, TOXIC, AND MESSY
1989 Exxon Valdez Oil Spill: 42,000 tons of crude oil gushed into the water polluting over 3000
miles of coastline. Ecosystem fell apart.
Eutrophication
Some household detergents contain phosphates.
Too many nutrients can cause environmental problems
Eutrophication: the process in which lakes and ponds are changed by excess plant nutrients
Nutrients get in water and then there is an Algae Bloom. It uses up all CO2 and then they can’t
live without CO2 so they die out. The Decomposers eat it, and in order for them to do that they
use up all the oxygen making a pond lifeless.
More than 65% of lakes have been affected by Eutrophication
Chesapeake Bay Eutrophication: Rivers carried farm fertilizers into the Bay and many organism
had a sharp decline.
Chemical Pollutants
Factories/Industry produces organic and inorganic such as Minamata
Farms produce Pesticides, Fertilizers, and Manure
House’s/Residence produce human waste and salts
Mining produce radiation and heavy metals
Construction
21.3
Nuclear Power plants produce large amounts of Radioactive water and wastes.
Radioactivity
Tiny amounts of radiation are released into air and water near a nuclear power plant.
The wastes produced by Nuclear Power plants are dangerous, difficult to handle and dispose of.
Disposal of Radioactive Wastes
Liquid wastes are placed in steel storage containers. They are buried and sometimes they break
down allowing waste to leak into soil.
1973: 1 million L of radioactive waste leaked into soil from Hanford Nuclear weapons site, and it
eventually made its way to the Columbia River. 2100 people were exposed to dangerous
radiation.
Thermal Pollution
Factories give off large amounts of heat that can pollute water
Thermal Pollution: A large increase in water temperature due to human activity.
When hot water is mixed with cool water and is put back to sources
Occurs in place located near power plants or industrial sites
Water cooling systems are used to reduce heat
How Thermal Pollution affects ecosystems?
As water temp increases so does a fishes body temperature, and increased body temperature
increases metabolism.
Also it decreases the amount of dissolved oxygen the water can hold
Increased water temperature is destructive to fish eggs and young fish.
21.4
First act was Rivers and Harbors act of 1899
Many laws have failed because the laws are not strong enough and normally they are not
obeyed or enforced.
Before 1948 individual states were responsible for enforcing laws governing water pollution.
If a factory was charged with violating a law and fined the factory might threaten to move to a
state where laws are less strict. Many places do it to avoid fines and get laws suspended.
1972 Clean Water Act: Attempt to set quality standards for all 50 states. However it is not a set of
laws for enforcement.
Some have improved and some places still have issues
PATHOGENS
Cholera: Bacteria
Malaria: Protozoan
Dysentery: Bacteria/Protozoan
Shistosomiasis: Worm