Transcript Chapter 14 - Water Pollution

Chapter 14
Water Pollution
Water Pollution
The contamination of streams, rivers, lakes, oceans, or
groundwater with substances produced through human
activities and that negatively affect organisms.
Point sources- distinct locations that pump waste into a
waterway.
Nonpoint sources- diffuse areas such as an entire farming
region that pollutes a waterway.
Types of pollutants:
Organic – human and animal wastes
Inorganic – not from living things
Nonchemical pollutants
Human Wastewater
Water produced by human activities such as human
sewage from toilets and gray water from bathing and
washing clothes or dishes.
Three reasons scientists are concerned about
human wastewater:
1.
Oxygen-demanding wastes like bacteria that put a
large demand for oxygen in the water
2.
Nutrients that are released from wastewater
decomposition can make the water more fertile
causing eutrophication
3.
Wastewater can carry a wide variety of diseasecausing organisms.
Biochemical Oxygen Demand (BOD)
BOD- the amount of oxygen a quantity of water uses over a
period of time at a specific temperature.
Lower BOD values indicate the water is less polluted and
higher BOD values indicate it is more polluted by
wastewater.
Organic pollution increases BOD due to action of
decomposers.
High BOD for decomposers  lower O2 levels for other
organisms, which can cause dead zones
Example of a dead zone: Gulf of Mexico at the mouth of the
Mississippi River
Eutrophication
Eutrophication is an abundance of fertility in a body of
water.
Cultural eutrophication is caused by an increase in
nutrients, such as fertilizers, especially N and P.
In natural systems, N & P are limiting factors – adding
them causes an algal bloom.
Eutrophication can cause a rapid growth of algae which
eventually dies, causing the microbes to increase
the BOD.
Common Diseases from Human
Wastewater
1/6th of the World’s population does not have access
to safe drinking water
Cholera*
Typhoid fever
Stomach flu
Diarrhea
Cholera
Hepatitis*
* Major water-borne diseases world-wide
Testing for pathogens
• Cannot look for all possible pathogens –
instead test for an indicator species
• Fecal coliform bacteria (E. coli is one
type) which live in human and animal
intestines
• Detecting the presence of these
organisms shows that organic waste is
in the water
Treatments for Human and Animal
Wastewater
Septic (meaning ‘with bacteria’) systems- a large container
that receives wastewater from the house.
Bacteria break down the organic material.
Advantage: relies on natural processes – no electricity needed
Disadvantage: tank must be pumped out every 5-10 years
Treatments for Human and Animal
Wastewater
Sewage Treatment Plants- centralized plants in areas with
large populations that receive wastewater via a network of
underground pipes.
Primary treatment – solid waste settles and dries to sludge
which is treated and sent to landfill, burned, or converted
to fertilizer
Secondary treatment – use bacteria to breakdown organic
matter to CO2 and inorganic nutrients. Aeration is used to
encourage aerobic bacterial growth (less odor).
Remaining water is released to local waterway.
Treatments for Human and Animal
Wastewater
Manure lagoons- large, human-made ponds line with rubber
to prevent the manure from leaking into the groundwater.
After the manure is broken down by bacteria, it is spread
onto fields as fertilizers.
Additional contaminants
Substance
Lead
Arsenic
Mercury
Acids
Pesticides
Pharmaceuticals
Hormones
Natural
sources
Anthropogenic
sources
Effects
Removal
Oil Pollution
Ways to Remediate Oil Pollution
Containment using booms to keep the floating oil from
spreading.
Chemicals that help break up the oil, making it disperse
before it hits the shoreline.
Bacteria that are genetically engineered to consume oil
No really good plans for:
Underwater plumes
Shoreline oil removal
Other Water Pollutants
Solid waste pollution (garbage) – most goes to
landfills, some goes in ocean
Sediment pollution (sand, silt and clay) – some
naturally occurring but much now is anthropogenic
Thermal pollution – usually an increase in temp. Can
cause thermal shock – warm H2O can hold much
less O2. Factories must use cooling towers before
putting water back in natural system.
Noise pollution – sonar and other noise can interfere
with whale communication.
Water Laws
Clean Water Act- (1972) supports the “protection and
propagation of fish, shellfish, and wildlife and
recreation in and on the water”.
Issued water quality standards that defined acceptable
limits of various pollutants in U.S. waterways.
Does NOT include groundwater
Water Laws
Safe Drinking Water Act- (1974, 1986, 1996) sets the
national standards for safe drinking water.
It is responsible for establishing maximum
contaminant levels (MCL) for 77 different elements
or substances in both surface water and
groundwater.
Latest data some good news
• In 2004, in the U.S. bodies of water that
support their ‘designated uses’
(aesthetics, recreation, protection of
fish, source of drinking water)
• 56% of all streams
• 35% of lakes & ponds
• 70% of bays & estuaries