Transcript Environmental Studies

Lecture 11
Lecture 10
Air & Noise Pollution
The Atmosphere
- thin, gaseous envelope of air around Earth
- we live at the bottom of this sea of air
The atmosphere is divided into the:
Troposphere
-
atmosphere’s inner layer
contains most of Earth’s air
N2 ( 78% ), O2 ( 21% ), CO2 ( 0.04% )
weather occurs here
temperature drops with an increase in altitude
Stratosphere
- layer above troposphere
- temperature rises with altitude
- our global sunscreen
Stratosphere cont’d
- contains O3 “good ozone”
- ozone layer prevents 99% of harmful ultraviolet
radiation from reaching Earth’s surface
Ozone in the Troposphere
(Pollutant)
Trace amounts of O3 that form in the troposphere
as a component of urban smog cause damage to:
•
•
•
plants
materials, e.g., rubber
respiratory systems of humans & other
animals
What is Air Pollution?
- one or more chemicals in high enough
concentrations in the air to:
1)
harm organisms or materials
2)
alter climate
- these chemicals are called air pollutants.
Sources of Air Pollution
1. Natural events
(e.g., volcanic eruptions, dust storms)
2. Human activities
(e.g., emissions from cars and smoke stacks)
Major Air Pollutants
1. Carbon Dioxide ( CO2)
• linked to global warming
2. Sulfur Dioxide (SO2)
• Linked to global warming, acid deposition
3. Nitrogen Oxides
• Linked to global warming
Major Classes of Air Pollutants cont’d
4. Volatile Organic Compounds
- e.g., methane, propane, benzene,
chlorofluorocarbons (CFCs)
• found in paints and protective coatings
• have long-term health risks including:
 compromised immune system in infants
 respiratory disorders
Major Classes of Air Pollutants cont’d
5. Suspended Particles
- e.g., solid particles (dust, asbestos, soot)
- e.g., liquid droplets (pesticides, sulfuric acid)
- linked to respiratory disorders
Types of Air Pollutants
Primary Pollutant
- chemical, that occurs in a harmful
concentration, added directly to the air by
natural events or human activities
e.g. sulphur dioxide, carbon monoxide, carbon
dioxide
Types of Air Pollutants cont’d
Secondary Pollutant
- harmful chemical formed in atmosphere when
a primary air pollutant reacts with the
normal air components or with other air
pollutants
e.g. ozone, sulphur trioxide
Urban Air Pollution
Smog
- originally a combination of smoke & fog
- now describes other mixtures in the atmosphere
Urban Air Pollution cont’d
Industrial Smog
- consists mainly of a mixture of sulfur
dioxide, suspended droplets of sulfuric acid
and a variety of suspended solid particles
- found in cities that burn large amounts of
coal and heavy oil which contain sulfur
impurities
SMOG IN CHINA
Effects of Climate & Topography on Air Pollution
• Areas with high average annual precipitation,
help cleanse the air of pollutants.
• Winds help sweep pollutants away and bring in
fresh air.
• Hills & mountains reduce the flow of air in
valleys below and allow pollutant levels to build
up at ground level.
Effects of Climate & Topography on Air Pollution cont’d
• Buildings in cities slow wind speed & reduce
dilution and removal of pollutants.
• The process of hot air rising and cold air sinking
causing continual mixing of air, helps keep
pollutants from reaching dangerous levels near
the ground.
Temperature Inversion
- also called thermal inversion
- a layer of warm air settles over a layer of cooler
air that lies near the ground.
- the warm air holds down the cool air and prevents
pollutants from rising and scattering allowing
them to build up to harmful levels
THERMAL INVERSION
Smoke rising in Lochcarron, Scotland is stopped by an overlying layer of
warmer air – thermal inversion
Acid Deposition
- the falling of acids and acid-forming compounds
from the atmosphere to the earth’s surface
- commonly known as acid rain
Acid Rain
- refers only to wet deposition of droplets of acids
and acid-forming compounds
- natural precipitation is slightly acidic (pH 5.05.6)
- acid rain can have a pH of 4.3 or 3 (as acidic as
vinegar)
Harmful Effects of Acid Deposition
- contributes to human respiratory diseases
- damages foliage and weaken trees
- contaminate fish
- damages statues, buildings, metals, & car
finishes
- releases aluminium ions which damage tree roots
Greenhouse Effect
- natural effect that traps heat in the troposphere
- some of the heat flowing back toward space from
Earth’s surface is absorbed, by H2O vapour, CO2,
O3 and other gases, then radiated back toward
Earth’s surface
Greenhouse Gases
- gases in the troposphere that cause the
greenhouse effect
- include:
carbon dioxide
chlorofluorocarbons (CFCs)
ozone
methane
water vapour
nitrous oxide
Greenhouse Gases cont‘d
- the 2 predominant greenhouse gases are:
- water vapour
- carbon dioxide
- if the atmospheric concentrations of these gases
increase, the average temperature of the
troposphere will gradually rise
Global Warming
- warming of atmosphere due to increases in the
concentrations of one or more greenhouse gases
primarily as a result of human activities, mainly:
burning of fossil fuels
use of CFCs
agriculture
deforestation
Global Warming cont’d
In recent decades certain greenhouse gases have
increased in concentration:
carbon dioxide
methane
nitrous oxide
CFCs
CO2 contributes to ~ 55% of global warming.
Global Warming cont’d
Possible Impacts of Global Warming
on Caribbean States
- disastrous for ecosystems e.g. coral reefs (coral
bleaching)
- alter climatic conditions faster than some species
could adapt
- shift food-growing areas
- rise in sea levels due to melting of icecaps and
glaciers may flood coastal settlements
Meltwater from Ice Sheet in Greenland flowing into ocean
http://www.sciencedaily.com/releases/2009/06/090612092741.htm
Possible Impacts of Global Warming on
Caribbean States cont’d
- more frequent and fierce hurricanes
- disastrous for economic and social systems
Ozone Layer
- layer of gaseous ozone that protects life on Earth
by filtering out harmful ultraviolet radiation
from the sun
- being depleted by CFCs, halons and other
chemicals
CFCs
- Chlorofluorocarbons
- used in air conditioners, refrigerators, aerosol
spray cans, cleaners for electronic parts,
hospital sterilants, fumigants, plastic foam
- ozone eaters
Impact of Ozone Depletion
- increased cases of cancer & cataracts
- suppression of human immune system
- lowers crop yield
- degradation of materials
- reduction in phytoplankton
Noise Pollution
- any unwanted, disturbing or harmful sound that
impairs or interferes with hearing, causes stress,
hampers concentration and work efficiency or
causes accidents
Impact of Noise Pollution
- permanent hearing loss
- hypertension
- insomnia
- irritability
- migraine headaches
- muscle tension
- gastric (stress) ulcers
- psychological disorders (eg, increased aggression)
Solutions to Air & Noise Pollution
- enforce air & noise pollution laws
- use emission control devices
- ban or limit smoking to well-ventilated areas
- tax each unit of pollution produced
- use office machines in well-ventilated areas
- shift to less polluting energy sources
- increase intake of outdoor air
- car exhaust inspections