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major pollutants and their sources
nutrients, dediments, pathogens, oil, persistent cources, plastic sources, radiotive isotopes, thermal , aliean species, noise!
sources: forestry, erosion, construction, dredging
effects: increases in turbidity, smothers reefs, clogs fish
sources: runoff, agriculture, forestry, sewage, industry (not as big)
effects: eutrophications, phase-shift, dead zones, algae blooms
sources: sewage, livestock
effects: disease
persistent toxins
sources: DDT, PCBS, Industry, landfills, agro
effects: toxic, food webs, bioaccumulation
sources: Fishing nets, garbage from cargo and cruise ships, beach litter, industry, landfills.
effects: Can entrap marine life or be ingested. May persist for 400 years! NOT EASILY BROKEN DOWN
radioactive isotopes
CAUSES: Illegal dumping, medical waste, military accidents, nuclear weapons testing.
EFFECTS: Carcinogenic and persistent for thousands of years.
CAUSES: power plants
EFFECTS: Alters coastal ecosystems.
CAUSES: Shipping, navy sonar testing.
EFFECTS: arguably disrupts marine life (whales who use sonar)
alien species (ballast water)
CAUSES: Ballast water of ships, canals, aquaculture.
EFFECTS: Out compete native species; reduce marine biodiversity, new diseases.
land-based sources*
Land-based sources account for 77% of marine pollution and are the most difficult to control.

33% airborne emissions from land (cars, industry, incineration)
44% run-off in rivers and streams
point/non-point sources*
A point source has a clearly identifiable origin (e.g. the discharge from a specific factory) and is easier to identify and regulate.
Non-point sources come from wide areas (e.g. pesticide run-off from an agricultural area, storm drains in a residential area) and are more difficult to identify and regulate.
Torrey Canyon Spill (1967)
The first really big oil spill to mobilize international prevention efforts was the Torrey Canyon in 1967 off the coast of Cornwall (120,000 tonnes spilled).
Exxon Valdez spill (1989)
led to the US Oil Pollution Prevention Act of 1990. A key provision of this law is to require all tankers operating in US waters to have double hulls by 2015; and all single hull tankers older than 23 years to be phased out by 2005. [See Box 11.1 in textbook]
Prestige spill (2002)
(coast of Spain 2002) led the IMO to adopt an accelerated phase-out schedule for single-hull tankers, requiring ships constructed before 1984 to be replaced by 2010.
double-hull tankers*
controversy over double-hulls as some shipping companies may maintain double hulls less because of cost

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