Transcript Cell Division and Mitosis - Randolph

Human Impact on the Biosphere
Chapter 50
Pollutants
are substances with which ecosystems have no prior
evolutionary experience and therefore cannot deal with them
Carbon oxides
CO, CO2
Sulfur oxides
SO2, SO3
Nitrogen oxides
NO, NO2, N2O
Volatile organic
compounds
CH4, CFC’s,
Photochemical oxidants
Ozone, H2O2
Suspended particles
Dust, soot, lead, pesticides
Each day 700,000 metric tons of pollutants are dumped into the
atmosphere in the US alone
SMOG
cooler air
cool air
Thermal Inversions are when weather conditions trap a layer
of cool, dense air under a layer of warm air. Thermal
inversions can trap pollutants close to the ground
cooler air
Normal air
circulation pattern
cool air
warm air
cool air
Air pollutants trapped
under a thermal
inversion layer
warm inversion air
cool air
cooler air
cool air
SMOG
Industrial smog - is gray air found in industrial cities
that burn fossil fuel (usually in cities that are cold and wet)
Photochemical smog - is brown air found in large cities
in warm climates, the key culprit is nitric oxide.
Acid Rain
Burning coal & metal smelting
produces sulfur dioxides
Burning fossil fuels, vehicles
and fertilizers result in nitrogen
oxides
Tiny particles of these oxides
can fall to the earth in 2 forms:
- Dry acid deposition
- Acid Rain
Average acidities of precipitation in the United States in 1998
Major coal-burning power and industrial plants
>5.3
5.0-5.1
4.7-4.8
4.4-4.5
5.2–5.3
4.9–5.0
4.6–4.7
4.3–4.47
5.1–5.2
4.8–4.9
4.5–4.6
>4.3
Ultrafine particles reach alveoli in lungs and contribute to
respiratory disorders. High concentrations can cause lung cancer.
Ultrafine particles
Fine particles
Large particles
metallurgical dust, fumes
photochemical smog
tobacco smoke
carbon black
combustion
sea salt
oil smoke
paint pigments
cement dust
fly ash
insecticide dust
coal dust
milled flour
pollen
0.001
0.01
2.5
10.0
Average particle diameter (µm)
100
Greening Sudbury
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
CNN 1997
Ozone Thinning Why is the loss of the Ozone Scary?
Ozone protect us from UV radiation!
Ozone in the lower stratosphere absorbs most of
the UV radiation from the sun.
- the thinning of the ozone layer has produced
a seasonal ozone “hole” over Antartica
- in response, skin cancer has increased,
cataracts may increase, and phytoplankton
may be affected
Chlorofluorocarbons (CFC) seem to be the cause
- one chlorine atom can convert 10,000 ozone
molecules to oxygen.
Ozone Thinning Top 1979,
Middle 1991
Bottom 1996.
ice clouds
Lowest ozone
values are in magenta and purple.
Ozone Thinning
Antarctica
CFC’s
Refrigerators and air conditioning solvents
Plastic foams
CFC’s in Air
Light rays
O3
Free Cl
O2 + ClO
Each Cl can convert 10,000 O3 to O2
Ozone Destruction animation…
Where to put Solid Wastes? Where to produce food?
In NATURAL ecosystems, one organism’s waste serves as resources
for others.
Paper products and non-returnable bottles and cans are perhaps our
biggest problem.
- each week 500,000 trees end up as Sunday newspapers in US
- if every reader recycled just 1 out of 10 papers, we could save
25 million trees a year
- recycling paper could reduce air born pollutants released by
paper manufacturing by 95% and requires 30 to 50% less energy
than making new paper
We face a challenge to move from a “throw-away” society to one of
conservation and re-use. Land fills leak and threaten groundwater.
What if we burn wastes instead? - greater amount of air pollution
Where to put Solid Wastes? Where to produce food?
Converting Marginal Lands
for Agriculture
- Almost 21% of land is used
for Agriculture; another 28%
is available but may not be
worth the cost
- the green revolution has
increased crop yields but uses
many times more energy and
mineral resources
- a growing human population
is moving into marginal lands
to meet our increasing needs
cultivated
tropical
forest
arid lands
11%
grazed
10%
forests,
arid lands
8%
14%
6%
51%
ice, snow, deserts,
mountains
At one time tropical forest cloaked regions that
were collectively 2X the size of Europe and
home of 50-90% of all land dwelling species.
In  4 decades humans have destroyed more
than half of the forests and most of the
species.
Each year another 34 million acres is logged
over = to leveling 34 city blocks every minute.
Deforestation - the removal of all trees from large tracts
of land for logging agriculture and grazing.
In Shifting cultivation (slash-and-burn agriculture) trees are cut, the land
used for a few growing seasons and then abandoned as fertility plummets.
Deforestation
Forest are watersheds; they control erosion, flooding, & sediment
buildup in rivers and lakes.
Deforestation can
- reduce fertility
- change rainfall patterns
- increase temperatures
- increase carbon dioxide (CO2)
Clearing large tracts of tropical forest may have global
repercussions, such as altering:
- rates of evaporation
- rates of transpiration
- runoff of nutrients and rainfall
- photosynthetic activity rates.
Why are we destroying our forests?
Increase demand for lumber, fuel and other forest
products as well as for cropland and grazing land
When vegetation cover gets stripped away, the
exposed soil becomes vulnerable to leaching of
nutrients and erosion
In logged area, annual precipitation declines and rain
swiftly drains from the exposed nutrient poor soil.
-desert like conditions might prevail
Desertification is the conversion of grasslands and
croplands to desert-like conditions
Desertification, also applies when agricultural productivity
drops by 10% or more.
At least 200,000 sq. kilometers are being converted annually
- overgrazing of livestock on marginal lands is the main cause of
large scale desertification
- prolong droughts accelerate the process
A Global Water Crisis
Most of the earth’s water is too salty for human consumption or for
agriculture.
Desalination (removal of salt from sea water) processes are
available and can be used when absolutely necessary.
However, desalinization is not cost effective in most locales and it
uses valuable fuel reserves to provide the energy for the
desalination equipment, also produces mounds of salt.
Consequences of heavy irrigation - large scale agriculture account for nearly 2/3 of the human population’s
use of fresh water (“piped in water” - high in mineral salts)
- salt buildup (salinization) of the soil and waterlogging can results
- withdrawl of underground water causes water tables to drop
A Global Water Crisis
Water Pollution - amplifies the problem of water scarcity
Causes ?
- radioactive materials
- human wastes
- insecticides
- herbicides
- chemicals
- heat
The Coming Water Wars
Water, not oil, may become the most important fluid of the 21st
century. National, regional and global policies for water usage
and water rights have yet to be developed.
In the past decade, 33 nations have engaged in conflicts over
reductions in water flow, pollution, and silt buildup
By restricting water flow, countries upstream may attempt to
influence political behavior in countries downstream.
By building dams and irrigation systems at the headwaters of the
Tigris and Euphrates rivers, Turkey could stop the water flow in
Syria and Iraq for as long as eight months “to regulate their
political behavior”.
Fossil Fuels are limited resources, extraction costs are
increasing and atmospheric levels of carbon, nitrogen and
sulfur oxides are also increasing.
A Question of Energy Inputs
Increases in human population and extravagant life-styles
has increased energy consumption.
Extraction and use of abundant reserves of oil shale and coal are
not “environmentally attractive” - environmental cost
Valdez tanker ~11 million gallons of oil spilled near the
Alaskan coastline
Coal burning is primary source of air pollution contributing
to acid rain and greenhouse effect.
Extensive strip mining of coal reduces the land available for
agriculture, grazing, and wildlife; restoration difficult
Developed Countries
Nuclear
power 5%
Developing Countries
Hydropower, geothermal,
solar 7%
Hydropower, geothermal,
solar 6%
Biomass
3%
Nuclear
power 1%
Natural
gas
25%
Biomass
35%
Natural gas
7%
Coal
25%
Oil
37%
Coal
25%
Oil
26%
A Question of Energy Inputs
Nuclear Energy
- with nuclear energy, the net energy produced is low and
the cost is high compared with coal-burning plants
- meltdowns may release large amounts of radioactivity to
the environment
- nuclear waste is so radioactive that it must be isolated for
10,000 years.
April 26, 1986 — Chernobyl in Ukraine
Nuclear fuel burned for 10 days right through a
6-foot thick steel and gravel barrier
Distribution of radioactive fallout within 2
weeks of the meltdown - Reached Europe
Made crops & live stock unfit for consumption
April 27
May 2
April 30
May 6
After soviet union's breakup, some underpaid
workers of a Russian nuclear power plant have
been selling fuel elements on the black market.
The buyers?
Developing nations that want to produce
nuclear weapons - possibly deliver them to the
hand of terrorist organization
Alternative Energy Sources
(1) Solar-Hydrogen Energy
Solar-hydrogen energy is an attractive technology b/c it
depends on a renewable energy source … The SUN!
Photovoltaric cells produce an electric current that splits
water into oxygen and hydrogen gas (H2) which can be used
directly as fuel or to produce electricity
In 1995 - these cells generated almost 4 million
kwatt hours of net electricity in the US
Alternative Energy Sources
(2) Wind Energy
- where wind travels faster than 7.5 meters per sec, wind
turbines are cost-effective producers of energy
- b/c winds do not blow on a regular schedule, wind
turbines cannot be the exclusive source of energy
Alternative Energy Sources
(3) Fusion Power
- temperatures like those on the sun cause atomic nuclei to
fuse and release energy
-fusion power on earth is possible but many obstacles make
the technology a distant possibility
-Researchers confine a heated gas of two isotopes of
hydrogen in magnetic fields, then bombard it with lasers.
The fuel (hydrogen) implodes and energy is released.
“ If we make the transition to an energyefficient solar-hydrogen age, we can say
good-bye to smog, oil spills, acid rain,
and nuclear energy, and perhaps to global
warming. The reason is simple. As
Hydrogen burns in air, it reacts with
oxygen gas to produce water vapor – not
a bad thing to have coming out of
tailpipes, chimneys, and smokestacks.”
-G. Tyler Miller, Jr. (Environmental Scientist)