LECTURE NOTES: ENVIRONMENTAL BIOLOGY (ENVS 105)
SNYDER, L.
Ozone Depletion, Global Warming, Water Pollution
Ozone (O3) Depletion
 Protects us from Ultraviolet (UV) light exposure from sun
 O3 formed in stratosphere
o Oxygen (O2) formed in troposphere rises up in the atmosphere to the
stratosphere where UV light breaks down O2
o O2 Reforms as O3
Ozone destruction by CFC’s & Other Chemicals (halocarbons, methyl bromide,
carbon tetrachloride, etc.)
1. Ozone depleting chemicals (ODC’s) spewed into atmosphere from industry
(factories), homes, farms, etc.
2. ODC’s rise up into atmosphere where they are broken down by sunlight
EX: CFCL3 → CFCl2 + Cl (Chlorine (Cl) atoms are freed)
3. These breakdown products bond with ozone & destroy ozone.
EX: CFC’s Cl atom breaks up ozone (Cl + O3→Cl+ O + O2)
4. Chlorine (or bromine, etc.) atom not used up in reaction:
 One Chlorine atom can break up 100,000 O3 molecules
As CFC’s & other Ozone Depleting Chemicals increase in the atmosphere, ozone in
the stratosphere decreases
But, ozone depletion has leveled off in last ~ decade. Why?
Ozone Hole (Thinning Ozone Layer)
 Greatest at South Pole (Antarctica)
 From Aug–Dec (Southern spring-summer)
 In warm months, Solar radiation increases & breaks up CFC’s
 Results in decreased Phytoplankton productivity (photosynthesis) from Aug-Dec
UV Radiation hitting Earth Increases as Ozone Decreases
 Results in increased skin cancer rates
 Malignant Melanoma (what to look for in moles, freckles, lesions, etc.)
o A (Asymmetry)
o B (Border)
o C (color)& Growth
 In the past thirty years, skin cancer has tripled in women under age 40.
 Melanoma is the second most common cancer in women aged 25-29.
 Melanoma, the deadliest form of skin cancer, is rising faster than that of any other
cancer. There are now nearly 8,000 melanoma deaths every year.
 While melanoma is uncommon in African-Americans, Latinos, and Asians, it is
most deadly for these populations.
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More than 90 percent of all skin cancers are caused by sun exposure, yet fewer
than 33% of adults, adolescents, & children routinely use sun protection.
A person's risk for skin cancer doubles if he or she has had five or more sunburns.
Effects of Ozone Depletion
Increased exposure to UV rays:
 Cataracts (wear UV protective sunglasses)
 Skin cancers:
 1% decrease in O3 causes 5-8% increase in skin cancer
 Australia (close to Antarctic ozone hole): 4% decrease O3 has resulted in a 20%
increase in cancer
o Sunscreen, hat, protective clothing, etc., avoid sun (10 – 4 pm)
 Increase in DNA mutations results in other types of cancers
 Photosynthesis decreases (phytoplankton, algae, & plants decrease in
productivity)
Stratospheric Ozone Replenishment
 1987 Montreal Protocol: Global phaseout of CFCs by 2000 (53 nations)
o US ban 1993
o Developing nations (2010)
 Methyl Bromide (pesticide) phaseout by 2005!
o Many nations (U.S.A included) ask for exemptions
 CFC’s take 50-100 yrs. to leave atmosphere
o 2100 to reach “safe” O3 levels
Global Warming:
 Earth’s climate fluctuates slowly (geologic time)
 Warming since last ice age (18,000 yr ago)
 Since industrial revolution rate of increase has accelerated
 Result of enhanced greenhouse effect
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Trapping of heat by atmospheric gases
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Necessary for life on Earth
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Without it, Earth’s Avg. temp ~ 0°F (-18°C)
Greenhouse Gases: Carbon dioxide & Nitrogen oxides (fossil fuel burning, wood
burning), methane (cows, landfills), CFC’s (coolants, propellants)
 Absorb & trap escaping heat
Industrial Revolution:
 Unnatural levels of CO2 added to atmosphere by burning fossil fuels
 CO2 = #1 greenhouse gas
 We generate CO2 faster than Ocean & plants can absorb it
 Global Temp. has increased 5°C (9°F) since last ice age
 Greenhouse gases responsible for ~ 50% of increase
 10 warmest yrs on record all occurred since 1990

1998 hottest yr.
Some Effects of Global Warming
 Increased Air pollution (increased ozone in troposphere)
o Ozone created in troposphere is unnatural (created by burning fossil fuels)
o More ozone is created during warm weather periods
 Species migration (shift) toward poles (Extinction of species that can’t migrate)
 Increases storms, more intense storms (some areas, coasts, etc.)
 Increased drought (some areas)
 Increased incidence of pest-borne diseases (malaria)
 Loss of coastal land due to rising sea level
Global Warming Impacts
 Sea level rising (melting ice sheets & caps, glaciers, etc.)
 Loss of low-lying coastal land
o Many shallow islands would be submerged (Ex: Maldives)
 Alter strength of ocean currents (Gulf stream = ice age in N. Atlantic)
 Increased Tropical storms (greater number & intensity)
 Warmer ocean:
o Decrease in phytoplankton
o Extinction of species with limited temperature ranges (coral, polar bears)
Thermohaline Circulation (Global Ocean Conveyer Belt):
Some Cold water warms near Equator
Deep, cold, salty water moves under Warm Surface Currents
Global Conveyer Belt: Movement of Deep, Cold, Salty Water From Atlantic To Pacific
Dense, sinking water causes convection that helps drive Deep Circulation
Excess Freshwater entering N. Atlantic may stop Thermohaline circulation (Melting ice
& River inflow from ice sheets, glaciers, etc.)
Halt movement of Gulf Stream in Atlantic Ocean
Global Warming could cause N. Europe & America to Cool Significantly!
The Role of Industrialized Nations
 Industrialized nations currently use 60% of world's fossil fuels (USA 25%)
 U.S.A. (5% of world's population), 30% of world's global warming pollution (#1)
 U.S. imports more than we export ($55 million trade deficit)
 What if everyone used resources & polluted as much as us?
 Kyoto Protocol – world agreement to reduce greenhouse gases (U.S has not
signed)
Effect of World Population on Global Warming & Pollution
 As World Population Grows, Resource use & Pollution increase & global
warming increases
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On 14 May 2006: 6.52 Billion People on Earth
In 1850 (beginning of industrial Revolution) there were 1 billion people
What Can Be Done?
Global temp. estimated to increase 10.5 °F in next century as energy demands increase
We all share Earth’s resources & we ALL contribute to its degradation
Individual action
Recycle, Buy recycled & EnergyStar products
Conserve resources
Plant trees & gardens
Reduce Chemical use
Use Mass transit, carpool
Stop cutting down forests (rainforest)
Fuel alternatives, fuel-efficient autos, hybrid vehicles
Proper tire inflation
Don’t idle car
Educate others
Choose seafood wisely
Clean up after yourself!
“Never doubt that a small group of thoughtful, committed citizens can change the world.
Indeed, it's the only thing that ever has.”
– Margaret Mead
Water Pollution
 Point source: Clear origin or source
o Sewage outfall, oil tanker spills, industrial plant, utilities
 Non-point-source: Many diffuse sources
o Urban runoff, boats (harbors & marinas), invasive species, agriculture,
trash & debris, construction, air pollution
Solid Waste Pollution in Ocean
 Most discarded on land & carried to ocean via storm drains, rivers as urban runoff
 10% plastic
 Biodegrades SLOWLY (6-pk holder =400 yr)
 Americans produce 1,100 lbs plastic waste/person/yr.
 Cigarettes: thrown in streets, out of cars, etc. makeup HUGE percentage of
beach/coastal pollution (filters don’t biodegrade)
Plastic in Marine Environment:
 Floats
 Ingested by and entangles marine animals
 100,000 marine mammals die each yr.
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2 million seabirds
Sea Turtles: mistake plastic bags for their sea jelly (jellyfish) prey
Fishing line, cups, bags, straws….
Sewage Treatment & Outfalls
Primary Tr. - large solids, grease removed
Secondary Tr. – Good bacteria eats organic solids, chlorine kills bacteria,
chlorine removed (via chemicals)
22% of biosolids used by
farmers or compost centers
Many chemical toxins, heavy metals, pharmaceuticals not removed & enter ocean
Oceanic Oil Spills
Oil released in sea will eventually float to & rest in intertidal
Most oil in marine environment enters via urban runoff, dumping
Effects of spilled oil depends on type:
Light refined petroleum (diesel & gas) – mixes in H2O column, more toxic, but
evaporates quickly & doesn’t persist in environment
Crude – less toxic, but remains on water surface or shoreline much longer, sinks
Oil Tanker Spills
Small portion of total marine spills
Locally devastating, major cleanup
U.S. Oil Pollution Act 1990 (response to Exxon Valdez): all oil-carrying vessels must
have double-hull
Exxon still appealing $5 billion fine (17 yrs)
Oil Spills & Marine Life
Clogs gills of fish & benthic species
Damages digestivesystem
Mammals & birds (fur, feathers) lose
bouyancy & insulation
Oil Spill Cleanup
Scrubbing w/ high pressure, hot water increases damage
Leave it alone, rely on natural processes
Shovels, buckets, absorbent materials, booms
Bioremediation by oil digesting bacteria