Transcript Water Pollution

CHAPTER
3
Earth’s Environmental Systems
The Gulf of Mexico’s
Dead Zone
• Nutrient-rich runoff causes plankton blooms and
hypoxia—low oxygen levels—in the Gulf of Mexico.
• Hypoxia kills or displaces marine organisms, causing a
decline in the fisheries and the fishing industry.
• U.S. government and farmers debate the need to cut
down on fertilizer use.
Talk About It Do you think the distance between the source of
the nitrogen and phosphorus and the dead zones themselves
makes it difficult to manage this problem? Why or why not?
Lesson 3.2 Systems in Environmental Science
Positive feedback loops can help
erosion turn a fertile field to desert in
just a few years.
Dust storm, Stratford
Texas, 1930s
Lesson 3.2 Systems in Environmental Science
Interacting Systems
• Inputs into Earth’s interconnected systems include energy,
information, and matter.
• Feedback loops regulate systems.
Negative feedback loop
• Negative feedback
loops: Result in
stabilization
of a system
• Positive feedback
loops: Result in a
system moving
to an extreme
Did You Know? Predator-prey cycles are negative feedback loops.
If prey populations rise, predator populations can rise in response,
causing prey populations to fall. Then predator populations may
decline, allowing prey populations to rise again, and so on.
Lesson 3.2 Systems in Environmental Science
Spheres of Function
• Earth can be divided into spheres that are defined
according to their location and function.
Lesson 3.3 Earth’s Spheres
The movement of Earth’s plates has
formed the deepest ocean trenches
and the highest mountains.
Lesson 3.3 Earth’s Spheres
The Geosphere
• Rocks and minerals on and below Earth’s surface:
• Crust: Thin, cool, rocky outer
“skin”
• Mantle: Very hot and mostly solid
• Core: Outer core is molten metal,
inner core is solid metal
Rock formation, Ouray National Wildlife Refuge, Utah
Lesson 3.3 Earth’s Spheres
Plate Tectonics
• Crust and mantle are divided
into:
• Lithosphere: Crust and
uppermost mantle; divided into
tectonic plates
• Asthenosphere: Soft middle
mantle; heated by outer core
• Lower mantle: Solid rock
• Convection currents in the
asthenosphere move tectonic
plates.
• Collisions and separations of
the plates result in landforms.
Volcano lava
Lesson 3.3 Earth’s Spheres
Tectonic Plates
• There are three major types of plate boundary:
• Divergent
• Transform
• Convergent
Lesson 3.3 Earth’s Spheres
Divergent and Transform Plate
Boundaries
• Divergent boundaries:
Rising magma pushes
plates apart.
Divergent plate boundary
• Transform boundaries:
Plates slip and grind
alongside one another.
Transform plate boundary
Lesson 3.3 Earth’s Spheres
Convergent Plate Boundaries
• Plates collide, causing one of two things to happen:
• Subduction: One plate slides beneath another.
• Mountain-building: Both plates are uplifted.
Lesson 3.3 Earth’s Spheres
The Biosphere and Atmosphere
• Biosphere: The part of Earth in which living and
nonliving things interact
• Atmosphere: Contains the gases that organisms
need, such as oxygen; keeps Earth warm enough
to support life
Earth’s atmosphere, seen from space
Lesson 3.3 Earth’s Spheres
The Hydrosphere
• Consists of Earth’s water
Greenlaw Brook, Limestone, Maine
• Most of Earth’s water
(97.5%) is salt water.
• Only 0.5% of Earth’s
water is unfrozen fresh
water usable for drinking
or irrigation.
• Earth’s available fresh
water includes surface
water and ground water.
Did You Know? If it is depleted, groundwater
can take hundreds or even thousands of years
to recharge completely.
Lesson 3.4 Biogeochemical Cycles
A carbon atom in your body today may have
been part of a blade of grass last year, or a
dinosaur bone millions of years ago.
Fossilized bones in a
Colorado dig.
Lesson 3.3 Earth’s Spheres
The Water Cycle
Lesson 3.4 Biogeochemical Cycles
Nutrient Cycling
• Matter cycles through the
environment.
• Matter can be transformed, but
cannot be created or destroyed.
• Nutrients, matter that organisms
require for life process, circulate
throughout the environment in
biogeochemical cycles.
Did You Know? Organisms require several
dozen nutrients, such as nitrogen, phosphorus,
and carbon, to survive.
Lesson 3.4 Biogeochemical Cycles
The Carbon Cycle
Lesson 3.4 Biogeochemical Cycles
The Phosphorus Cycle
Lesson 3.4 Biogeochemical Cycles
The Nitrogen Cycle
Lesson 14.2 Uses of Fresh Water
One third of all the people on Earth
are affected by water shortages.
Next time you
take a drink,
think about
where that
water might
have been
before.
Next time rain drops fall on you, think
about where that water might have been
just a few days ago.
Water is a powerful force on Earth’s surface
Water is critical to life…how long can you
survive without it?
It is a precious
resource we often take
for granted
It is sacred to some : The Maya believed natural wells, such
as the Xkeken cenote in Mexico's Yucatán, led to the
Why Does Ice Float?
Why is the ocean cool even when its 100
degrees out?
How Can Water Make It All The Way To
The Top Of Trees
Water Is Unique
•Can’t live without
•Takes long time to
change temperature
•Stays liquid over large
range of temps.
•Expands when freezes
•Great at dissolving
things
•Commonly found as
solid, liquid and gas
According to the U.N., 1 billion people do
not have access to clean, reliable fresh water
How Much Water Do You Use
Average person
in U.S. uses
about 80
gallons a day
What can you learn from this chart?
Lesson 14.2 Uses of Fresh Water
How We Use Water
• Three main uses of fresh
water include:
• Agricultural
• Industrial
• Personal
Did You Know? The average
American uses 250 L of fresh water a
day for personal uses, such as
bathing and brushing teeth.
Lesson 14.2 Uses of Fresh Water
Using Surface Water
• Most freshwater used in the U.S. is surface water.
• Surface water is diverted by canals and dams.
• Drought and overuse have caused significant surface water depletion.
Did You Know? The Aral
Sea was once the fourth
largest body of fresh water.
Aral Sea, 1997
Aral Sea, 2009
Lesson 14.2 Uses of Fresh Water
Using Groundwater
• 68% of groundwater in the U.S. is used for
irrigation, most of which is very inefficient.
• Groundwater mining turns groundwater into a
nonrenewable resource because it is withdrawn
from the ground faster than it can be replaced.
• When groundwater is
depleted, the falling water
tables can cause cities to
sink, and undrinkable
saltwater to move into the
depleted aquifers.
Lesson 14.2 Uses of Fresh Water
Solutions to Freshwater Depletion
• Increase supply:
• Desalination: “Making”
fresh water by removing
salt from saltwater.
• Decrease demand:
• Agricultural: Dripirrigation, climateappropriate plants
• Industrial: Waterconserving processes,
recycling wastewater to
cool machinery.
• Personal: Xeriscaping,
water conservation
Desalination
Lesson 14.3 Water Pollution
3,800 children die every day
from diseases associated with
unsafe drinking water.
What is Water Pollution?
Water Pollution: is the
introduction of
chemical, physical, or
biological substances
that affects organisms
that depend upon it
•Many types of water
pollution
Lesson 14.3 Water Pollution
Types of Water Pollution
• Point-source pollution:
From a discrete location,
like a factory or sewer pipe
• Nonpoint-source
pollution: From many
places spread over a large
area, such as when
snowmelt runoff picks up
pollutants along its path
Point source oil pollution
Oil after a spill, Trinity Bay, Texas
Point Sources are
usually easily
identified
How can a farmer
in MT affect a
shrimp farmer in
Louisiana?
NON-Point
Lesson 14.3 Water Pollution
A-Nutrient Pollution
THE PROCESS OF
EUTROPHICATION
Nutrients
build up in
water.
Algae and
aquatic plant
growth
increases.
• Excess phosphorous and other
nutrients in the water is nutrient
pollution.
• Eutrophication occurs naturally.
• Nutrient pollution can cause cultural
eutrophication.
Organisms die.
Decomposition
requires
oxygen.
Dissolved
oxygen levels
decrease.
Lesson 14.3 Water Pollution
B- Toxic Chemical Pollution
• Occurs when harmful
chemicals are released into
waterways
• Can be organic or inorganic
• Harms ecosystems and
causes human health
problems
Lesson 14.3 Water Pollution
C- Sediment and Thermal Pollution
• Sediment pollution:
• Unusually large amounts of sediment that change an
aquatic environment
• Sediment pollution results from erosion.
• Can degrade water quality, cause photosynthesis rates to
decline, and disrupt food webs
• Thermal pollution:
• A heat source that raises the temperature of a waterway
• Heated water holds less oxygen.
Lesson 14.3 Water Pollution
D- Biological Pollution
• Biological pollution occurs when
pathogens enter a waterway.
• Biological pollution causes more
human health problems than any
other form of water pollution.
• Water treatment reduces
biological pollution.
Cholera bacteria
Did You Know? Giardiasis is
the most common form of
waterborne disease in the U.S.
Lesson 14.3 Water Pollution
E- Groundwater Pollution
• Sources of groundwater pollution
include natural sources, surface
pollutants leaching through soil, and
leaky underground structures.
• Chemicals break down more slowly
in groundwater than in surface water.
• Most efforts to reduce groundwater
pollution focus on prevention.
Did You Know? The EPA repairs and replaces leaky
underground gas storage tanks to reduce groundwater
pollution. Over the last 25 years, over 1.7 million tanks have
been repaired or replaced.
Acid drainage from a coal mine
Lesson 14.3 Water Pollution
F- Ocean Water Pollution
• Oil pollution in the ocean comes
from many widely spread small
sources. Natural seeps are the
largest single source.
• Ocean organisms bioaccumulate
mercury pollution.
A 2004 oil spill off the Alaskan coast
Did You Know? According to the U.S. Oil
Pollution Act of 1990, by 2015, all oil
tankers in U.S. waters must have double
hulls to help prevent against leaks.
• Nutrient pollution can cause red
tides.
Lesson 14.3 Water Pollution
Controlling Water Pollution
• Government regulation
decreases water pollution.
• The Clean Water Act
• Set water pollution
standards
• Required permits to release
point-source pollution
• Funded sewage treatment
plant construction
Lake Erie
Did You Know? The Great Lakes show that humans can
change their ways and clean up trouble spots. In the
1970s, Lake Erie was declared “dead” but is now home
to some flourishing species, especially the walleye.
Lesson 14.3 Water Pollution
Water Treatment
• Drinking water is treated to remove pollutants before
humans consume it.
• Wastewater is treated to remove pollutants before humanused water is released back to the environment.
Septic systems are the most popular method of
wastewater disposal in rural areas of the U.S.