LECTURE NOTES:
OCEANOGRAPHY (MARSC 100),
SNYDER, L.
CH. 18: Environmental Concerns
Marine Pollution
 Introduction into the ocean, by humans, substances or energy (heat, radiation) that
change water quality or affects:
o Physical, chemical, or biological environment
Main types of marine pollution
 Petroleum (oil)
 Sewage
 Synthetic Organic Chemicals (DDT, PCB)
 Heavy Metals (Mercury)
 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
Petroleum (oil) pollution
 Many sources including:
 Shipping (1.9 MMT/yr.) - much is incidental leakage
 Tanker accident (0.2 MMT/yr.) – NOT the largest source
o
Exxon Valdez is only 46th largest tanker spill in world history
o
22X volume of Exxon Valdez dumped in drains each YEAR!
 Drilling/pumping/refining operations (0.3)
 Urban Runoff carrying auto waste oil from streets, etc. (0.3)
 Intentional dumping
 Washes up on beaches
 Floats on sea surface
 Heavy components sink to seafloor
 Coat marine organisms (insulating fur or feathers useless), kill larvae, clog feeding
structures, block sun for photosynthesis
 Oil is Biodegradable (benthic & pelagic organisms – bacteria)
 Some can be cleaned up:
 Containment booms, skimmer ships, bottom scrapers, absorbent sheets
 Some old forms of cleanup too damaging: High pressure hot-water &
detergents
Heavy Metals
 Mercury & Lead (Industry, lead gas runoff)
 Copper & Tin (antifouling boat paint)
 Extremely toxic, Long-residence time
 Accumulates in living tissues
 Pregnant women MUST avoid Carnivore fish species (Tuna, swordfish, shark)

Minamata Disease
o Japan: Chemical plant released Mercury into watershed
o Contaminated fish
o Caused severe Neurological & birth disorders for babies born to Mom’s who
ate fish
Synthetic Organic Chemicals
 Rachel Carson’s book, Silent Spring (1962):
 Misuse of pesticides brought to public attention
 Chlorinated hydrocarbons (DDT, PCB): accumulate in higher trophic levels
(especially top carnivores)
 Biological Amplification
Synthetic Organic Chemicals
 DDT: Widely used pesticide
o Brown pelicans, ospreys, bald eagle, peregrine falcon produce thin egg
shells
o Endocrine disrupter (affects hormones of fish, etc. – males take on female
characteristics)
o Banned worldwide, still used in developing countries (malaria)
 PCB: Cool & insulate electrical devices, strengthen wood & concrete
o ↓ Reproductive fertility, weakens immune systems
o Dolphin, pinnepeds (nearshore populations (6,900 ppm)
o EPA: 5ppm (human), 50ppm (animal)
Fertilizers & Eutrophication
 Nutrients (animal waste) & Fertilizer enter ocean as runoff
 Sewage effluent, farms, ranches, homes, golf courses
 ↑ Growth of marine autotrophs
 Eutrophication:
 ↑ Nutrients = ↑ algae & plankton growth = ↑ bacteria (use oxygen to decompose
algae) = ↓ oxygen = ↓ animals (fish kills & dead zones)
 Gulf of Mexico’s Anoxic (Low Oxygen) Dead Zone”
o “1999 “Dead zone” = 20,000 km2 (7,700 mi2)
o Cause: Fertilizer flowing into Gulf from farms in Mississippi River Basin
Solid Waste Pollution
 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.
 2 million seabirds
 Sea Turtles: mistake plastic bags for their sea jelly (jellyfish) prey
 Fishing line, cups, bags, straws….
Growth Hot Spots (Coastal pollution & degradation increases in heavily populated areas)
 >½ of us live in coastal areas
 127 million by 2010
 Northeast USA coast 35% of U.S. population
 Pacific USA coast 26%
 Results in Habitat Destruction, sewage effluent, urban runoff pollution
Marine Reserves:
 The answer to habitat desturuction & overfishing, bad mariculture?
 Estuaries, Mangroves, coral reefs
 Many proposed, but Not implemented yet
 Supposed to include No fishing zones
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.
 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

Trapping of heat by atmospheric gases

Necessary for life on Earth

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)
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
 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