Marine pollution is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide.Marine pollution is a growing problem in today’s world. Our ocean is being flooded with two main types of pollution: chemicals and trash. Chemical contamination, or nutrient pollution, is concerning for health, environmental, and economic reasons. This type of pollution occurs when human activities, notably the use of fertilizer on farms, lead to the runoff of chemicals into waterways that ultimately flow into the ocean. The increased concentration of chemicals, such as nitrogen and phosphorus, in the coastal ocean promotes the growth of algal blooms, which can be toxic to wildlife and harmful to humans. The negative effects on health and the environment caused by algal blooms hurt local fishing and tourism industries.Marine trash encompasses all manufactured products—most of them plastic—that end up in the ocean. Littering, storm winds, and poor waste management all contribute to the accumulation of this debris, 80 percent of which comes from sources on land. Common types of marine debris include various plastic items like shopping bags and beverage bottles, along with cigarette butts, bottle caps, food wrappers, and fishing gear. Plastic waste is particularly problematic as a pollutant because it is so long-lasting. Plastic items can take hundreds of years to decompose. This trash poses dangers to both humans and animals. Fish become tangled and injured in the debris, and some animals mistake items like plastic bags for food and eat them. Small organisms feed on tiny bits of broken-down plastic, called microplastic, and absorb the chemicals from the plastic into their tissues. Microplastics are less than five millimeters (0.2 inches) in diameter and have been detected in a range of marine species, including plankton and whales. When small organisms that consume microplastics are eaten by larger animals, the toxic chemicals then become part of their tissues. In this way, the microplastic pollution migrates up the food chain, eventually becoming part of the food that humans eat. Solutions for marine pollution include prevention and cleanup. Disposable and single-use plastic is abundantly used in today’s society, from shopping bags to shipping packaging to plastic bottles. Changing society’s approach to plastic use will be a long and economically challenging process. Cleanup, in contrast, may be impossible for some items. Many types of debris (including some plastics) do not float, so they are lost deep in the ocean. Plastics that do float tend to collect in large “patches” in ocean gyres. The Pacific Garbage Patch is one example of such a collection, with plastics and microplastics floating on and below the surface of swirling ocean currents between California and Hawaii in an area of about

1. Chapter 11
The Coastal Ocean
Essentials of Oceanography
7th Edition

2. Coastal waters
Relatively shallow areas that adjoin
continents
Heavily used for commerce, recreation,
fisheries, and waste disposal
Experience dramatic changes in salinity and
temperature

3. Salinity and temperature in the
coastal ocean
Figure 11-1

4. Estuaries
Estuaries are partially enclosed coastal bodies of
water
Examples of estuaries include:
River mouths
Bays
Inlets
Gulfs
Sounds
Formed by a rise in sea level after the last Ice Age

5. Classifying estuaries by origin
Coastal plain
Fjord
Bar-built
Tectonic
Figure 11-3

6. Examples of estuaries
Figure 11-4
Fjord estuary (Norway) Tectonic estuary
(San Francisco, CA)

7. Classifying estuaries by water
mixing
Vertically mixed
Slightly stratified
Highly stratified
Salt wedge
Figure 11-5

8. Coastal wetlands
Coastal wetlands are saturated areas that
border coastal environments
Brackish water conditions
Two most important types of coastal
wetlands:
1. Salt marshes (mid-latitudes)
2. Mangrove swamps (low latitudes)

9. Coastal wetlands: Salt marshes
and mangrove swamps
Figure 11-8

10. The value of coastal wetlands
Coastal wetlands are highly productive
areas that serve as fish nurseries for many
important species
Effectively filter polluted runoff from land
Problem: are viewed as worthless land, so
are often replaced with developments
(roads, housing, shopping, etc.)

11. Lagoons
Lagoons are shallow
coastal bodies of
water separated from
the ocean by a
narrow strip of land
such as a barrier
island
Figure 11-9

12. Mediterranean circulation
The Mediterranean
Sea experiences high
rates of evaporation
Causes inflow of
water at the surface
and outflow of high
salinity water below
Figure 11-11b

13. Pollution in coastal waters
Coastal waters are highly affected by
pollution because they are:
Heavily used
Close to sources of pollution
Shallow-water bodies
Not as well circulated as the open ocean

14. Marine pollution: A definition
The introduction by man, directly or indirectly, of
substances or energy into the marine environment,
including estuaries, which results or is likely to
result in such deleterious effects as harm to living
resources and marine life, hazards to human
health, hindrance to marine activities, including
fishing and other legitimate uses of the sea,
impairment of quality for use of sea water and
reduction of amenities. (World Health Organization)

15. Main types of marine pollution
Petroleum (oil)
Sewage sludge
DDT and PCBs
Mercury
Non-point-source pollution

16. Marine pollution: Petroleum
Oil spills can be
caused by:
Tanker accidents
Intentional
dumping
Drilling/pumping
operations
Figure 11-12

17. Marine pollution: Petroleum
Petroleum is biodegradable
Many pollution experts
consider oil to be among
the least damaging ocean
pollutants
Data from the 1989 Exxon
Valdez oil spill shows the
recovery of key organisms
Figure 11-13

18. Marine pollution: Petroleum
Various
processes act
to break up
and degrade
oil in the
marine
environment
Figure 11-18

19. Marine pollution: Petroleum
When oil washes up
at a beach, it can
negatively affect the
marine environment
Oil can coat marine
organisms and
render their
insulating fur or
feathers useless
Oil on the beach from the
Exxon Valdez oil spill, Alaska

20. Marine pollution: Sewage sludge
Sewage sludge is the
semisolid material
that remains after
sewage treatment
Much sewage sludge
was dumped offshore
until laws restricted
sewage dumping
Figure 11-21

21. Marine pollution: DDT
DDT was a widely used pesticide that
became concentrated in marine fish
DDT caused brown pelicans and ospreys to
produce thin egg shells
Worldwide, DDT has been banned from
agricultural use but is still used in limited
quantities for public health purposes

22. Marine pollution: PCBs
PCBs are industrial chemicals used as liquid
coolants and insulation in industrial
equipment such as power transformers
PCBs enter the marine environment through
leaks and from discarded equipment
PCBs can accumulate in animal tissues and
affect reproduction

23. Marine pollution: Mercury and
Minamata disease
Mercury has many industrial uses but is
extremely toxic
A chemical plant released large quantities
of mercury into Minamata Bay, Japan
Residents who ate highly contaminated fish
suffered neurological disease and birth
disorders (Minamata disease)

24. Marine pollution: Non-point-
source pollution
Non-point-source
pollution comes from
material washed down
storm drains as
“poison runoff”
Includes fertilizers,
pesticides, road oil,
and trash
Figure 11-26

25. Current law regulating ocean
dumping
The only
substance
that is illegal
to dump
anywhere in
the ocean is
plastic
Figure 11-27

26. Plastic in the marine
environment
Plastic:
Does not biodegrade
Floats
Has high strength
Is ingested by and
entangles marine
animals
Figure 11-28

27. End of Chapter 11
Essentials of Oceanography
7th Edition