HPU NCS2200 Earth Science For elementary education majors summer 2014 online class air pollution lecture part2

1. Atmosphere – Pollution Part 2

2. Regional Outdoor Air Pollution from Acid
Deposition
Acid deposition
Wet deposition Dry deposition
Wind
Transformation to
sulfuric acid (H2SO4)
and nitric acid (HNO3)
Nitric oxide (NO)
Acid fog
Ocean
Sulfur dioxide (SO2)
and NO
Windborne ammonia gas
and particles of cultivated soil
partially neutralize acids and
form dry sulfate and nitrate salts
Dry acid
deposition
(sulfur dioxide
gas and particles
of sulfate and
nitrate salts)
Farm
Lakes in
deep soil
high in limestone
are buffered
Lakes in shallow
soil low in
limestone
become
acidic
Wet acid deposition
(droplets of H2SO4 and
HNO3 dissolved in rain
and snow)
Fig. 17.9, p. 428

3. Acid Deposition in the US
Fig. 17.10, p. 428

4. Acid Deposition and Aquatic Systems
 Fish declines
 Undesirable
species
 Aluminum
toxicity
 Acid shock
Water
boatman
Whirligig
Yellow perch
Lake trout
Brown trout
Salamander
(embryonic)
Mayfly
Smallmouth
bass
Mussel
6.5 6.0 5.5 5.0 4.5 4.0 3.5
pH
Fig. 17.13, p. 430

5. Acid Deposition, Plants, and Soil
 Nutrient
leaching
 Heavy metal
release
 Weakens trees
Emissions
Effects of Weather
Acid
deposition
Dry
weather
Low
precipitation
Increased
evapotranspiration
Increased
transpiration
Lake
Groundwater
SO2 NOX
H2O2 O3
PANs Others
Increased
susceptibility
to frost,
pests, fungi,
mosses,
and disease
Dead leaves
or needles
Reduced
photosynthesis
and growth
Tree deathDamage
to tree
crown
Water
deficit
Nutrient
deficiency
Bark damage
Direct damage
to leaves
and needles
Leaching of
soil nutrients
Acids
and soil
nutrients
Damage to
fine roots Disturbance
of water
uptake
Disturbance
of nutrient
uptake
Soil acidification
Kills certain
essential soil
microorganisms
Release of toxic metal ions
Nitrate
Sulfate
Magnesium
Aluminum
Calcium
Potassium
Acids
Fig. 17.14, p. 432
See Connections p. 431

6. Acid Deposition and Humans
 Respiratory diseases
 Toxic metal leaching
 Decreased visibility
 Damage to structures, especially
containing limestone
 Decreased productivity and
profitability of fisheries, forests, and
farms

7. OZONE DEPLETION IN THE
STRATOSPHERE
• Less ozone in the stratosphere allows for more
harmful UV radiation to reach the earth’s
surface.
– The ozone layer keeps about 95% of the sun’s
harmful UV radiation from reaching the earth’s
surface.
– Chlorofluorocarbon (CFCs) have lowered the average
concentrations of ozone in the stratosphere.
– In 1988 CFCs were no longer manufactured.

8. OZONE DEPLETION IN THE
STRATOSPHERE
• Ozone thinning: caused by CFCs and other
ozone depleting chemicals (ODCs).
– Increased UV radiation reaching the earth’s
surface from ozone depletion in the stratosphere
is harmful to human health, crops, forests,
animals, and materials such as plastic and paints.

9. OZONE DEPLETION IN THE
STRATOSPHERE
• Since 1976, in Antarctica, ozone levels have markedly
decreased during October and November.

10. OZONE DEPLETION IN THE
STRATOSPHERE
• During four
months of each
year up to half of
the ozone in the
stratosphere over
Antarctica and a
smaller amount
over the Artic is
depleted.
Figure 20-19

11. Ozone Depleting Chemicals
• Chlorofluorocarbons (CFC)
• Halons
• Methyl Bromide
• Carbon tetrachloride
• Methyl chloroform
• Hydrogen chloride
• Sources of CFC’s
– aerosol propellants, cleaning solvents,
refrigerants and foam plastic blowing agents.

12. Fig. 20-18, p. 486
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and
leaving CFCl2.
Sun
Repeated
many times
The chlorine atom
and the oxygen atom
join to form a chlorine
monoxide molecule (ClO).
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Cl + O Cl + O2
UV radiation
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom off
it and leaving an oxygen
molecule (O2).
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
Cl

13. Effects of Ozone Depletion
• Human Health
– Worse sunburn
– More eye cataracts
– More skin cancers
– Immune system suppression
• Food and Forests
– Reduced yields for some crops
– Reduced seafood supplies due to reduced phytoplankton
– Decreased forest productivity for UV sensitive tree species
• Wildlife
– Increased eye cataracts in some species (dogs/cats)
– Decreased population of aquatic species sensitive to UV radiation
– Reduced population of surface phytoplankton
– Disrupted aquatic food webs from reduced phytoplankton
• Air pollution and materials
– Increased acid depostiion
– Increased photochemcial smog
– Degradation of outdoor paints and plastics
• Global Climate change
• Accelerated warming because of decreased ocean uptake of CO2 by phytoplakton
• CFC acting as greenhouse gas.

14. Fig. 20-22, p. 489
This long-wavelength
(low-energy) form of UV
radiation causes aging of the
skin, tanning, and sometimes
sunburn. It penetrates
deeply and may contribute to
skin cancer.
This shorter-wavelength (high-energy) form
of UV radiation causes sunburn, premature
aging, and wrinkling. It is largely responsible
for basal and squamous cell carcinomas
and plays a role in malignant melanoma.
Epidermis
Squamous Cell
Carcinoma
Basal Cell
Carcinoma
Melanoma
Sweat
gland
Dermis
Squamous
cells
Thin layer of
dead cells
Basal layer
Melanocyte
cells
Blood
vessels
Ultraviolet
B
Ultraviolet
A
Hair
Basalcell

15. Solutions
• Montreal Protocol
– landmark international agreement designed to protect the
stratospheric ozone layer.
– originally signed in 1987 ;substantially amended in 1990
and 1992.
– production and consumption of chlorofluorocarbons
(CFCs), halons, carbon tetrachloride, and methyl
chloroform--are to be phased out by 2000 (2005 for
methyl chloroform).
• CFC Substitutes
– HCFC’s, acidic or alkaline solutions for circuit boards
– Eliminate use of foam plastic containers
– Capture and recycle