Transcript Environmental Science: Air & Water Quality Issues

Environmental Science
Air & Water Quality Issues
Your name
University of Maine
Dept. of…
Environmental Science

Interdisciplinary


Traditional science, politics, social
organization, economics, ethics, …
Pollution and Policy



Addressing environmental problems and
concerns is not an easy task
Perceptions and opinions vary
Scientific knowledge and government policy
do not always agree
Air Quality

Global Warming



Ozone Depletion


Greenhouse Effect
1 oC average temperature rise last century
Protective layer allows our existence
Primary Air Pollutants

Affects us directly
Warming/Cooling is a Natural Process
(Pleistocene Epoch: last 4 million years)

~ 100,000 years: Earth’s climate cycle



80-85,000 years: “Ice Age”
15-20,000 years: warming period
We are currently about 18,000 years into
Earth’s latest warming period
Global Warming
Greenhouse Gases




Carbon Dioxide, CO2
Chlorofluorocarbons (CFCs), CCl3F
Methane, CH4
Nitrous Oxide, NOx


N2 + O2  2NO (nitrogen oxide)
2NO + O2  2NO2 (nitrogen dioxide)
Carbon Dioxide, CO2



Most abundant of the greenhouse gases
Contribution to global warming: 55%
Produced naturally


Respiration
Volcanic activity
Volcanic Activity
Carbon Dioxide continued…



Most abundant of the greenhouse gases
Contribution to global warming: 55%
Produced naturally



Respiration
Volcanic activity
Produced unnaturally

Waste product of combustion

Gasoline, coal, oil, natural gas, biomass, …
Factories
Automobiles
Steady Increase in CO2 Concentration
CO2 Sink


Plants and trees
absorb CO2, but…
Massive deforestation
makes the problem
worse

South American Rain
Forests, …
Chlorofluorocarbons (CFCs)


Contribution to global warming: 24%
Entirely the result of human activity




Refrigerant gases
Cleaning solvents
Propellants in aerosol containers
15,000 times more efficient at trapping
heat than carbon dioxide
CFCs, continued…




Many international efforts since 1987
aimed at reducing CFCs
In 1996, the U.S. stopped producing CFCs
CFC concentrations in the atmosphere
have stabilized and are expected to decline
Many developing nations still produce CFCs
Methane, CH4


Contribution to global warming: 15%
Biological Sources

Several kinds of bacteria
Abundant in wetlands and rice fields
 Stomachs of ruminant animals such as cattle

Methane, CH4

1 billion cows worldwide

A single cow can produce more than 14 cubic
feet of methane each day
Nitrous Oxide, NOx


Contribution to global warming: 6%
Primary sources


Fossil fuels
Fertilizers
Result
Ozone, O3


Good ozone vs. bad ozone
Ozone layer (good ozone)




Stratosphere 8-15 miles up
Absorbs 99% of damaging UV radiation
O3 + UV light  O2 + O
O2 + O  O3
The Atmosphere
Ozone Depletion



Reduction in ozone layer first observed in
the 1970s
CFCs are the main culprit
Chlorine radicals strongly react with O3



Cl + O3  ClO + O2
And if that’s not bad enough…
ClO + O  Cl + O2
Bad News about Ozone



CFCs destroy ozone and remove atomic
oxygen as well (O3 can’t recombine)
It can take 10-20 years for CFC molecules
to reach the stratosphere!
CFC molecules can react and destroy
ozone molecules for up to 120 years

Ozone depletion will worsen well into this
century before any improvements are seen
Primary Air Pollutants

Carbon monoxide, CO



Incomplete burning of fossil fuels
Single largest source: the automobile
100 ppm can cause dizziness and headaches
Primary Air Pollutants, continued

Particulates


Very small pieces of solid material
Particles can accumulate in the lungs
Repeated exposure > serious health effects
 Carcinogenic materials

Primary Air Pollutants, continued

Nitrous oxide, NOx


Primary source: automobile engine
NOx reacts with UV light to form smog




N2 + O2  2NO
2NO + O2  2NO2
NO2 + UV light  NO + O
O2 + O  O3
Smog

Two destructive components of smog

Ozone (bad ozone)
Mutagen
 Destroys chlorophyll in plants
 Injures lung tissue


Peroxyacetyl nitrates

Eye irritants
Smog, continued


Smog is a serious
problem in many
large cities
Especially those cities
ringed by mountains
So why does any of this matter to you?
Because we are not immune
The northeast is this nation’s tailpipe
Ground-level Ozone
Ozone isn’t the only pollutant
flowing through the northeast
Water Quality Issues

Acid Rain




Air pollutants react with moisture in atmosphere
Sulfur dioxide and nitrogen dioxide
SO2 + H2O + ½O2  H2SO4 (Sulfuric acid)
2NO2 + H2O  HNO2 + HNO3 (Nitric acid)
Acid-base pH scale



pH 7.0 ~ neutral
pH 5.6 ~ acid rain (25 times more acidic than pure water)
pH 3.0 ~ highly acid
Lakes become acidic



Healthy lakes have a pH
over 6.0
At a pH of 5.5, many
desirable species of fish
have been eliminated
Birth defects common
Trees and vegetation decline
Limestone deteriorates
You Can’t Hide From Acid Rain

The northeast is highly prone to severe
acid rain


pH 3.0 to 4.0 not uncommon
pH 2.3 worst recorded (1000 times more
acidic than pure water)
Other Water Quality Issues

Oil Spills
The End
Thank you