Download 13B R-Ocean Pollution Reading

Oceanography 10, T. James Noyes, El Camino College
13B-1
Ocean Pollution
What is Pollution?
My opinion is that we can either
use the ocean as a waste dump
or for recreation and food.
Either one is fine by me,
but using it for both is gross.
There are several definitions of pollution. For our purposes,
ocean pollution is any substance or “energy” that humans put
in the ocean which causes harm to living things. There are
two key aspects of this definition. First, humans have to
cause the pollution, and, second, the pollution has to do harm to living organisms. Dead seaweed
on the beach may be ugly, but it is not pollution, because humans did not put it there and, in
general, it does not harm anything. Pollution is not necessarily a “substance” like oil. For
example, human ships and navy SONAR can be very loud, and disrupt ocean animals’ ability to
communicate or navigate, or even deafen them. Thus, oceanographers sometimes talk about
“sound pollution” in the ocean. Also notice that polluting “substances” are not necessarily
unnatural (e.g., man-made). Mercury and oil are naturally occurring substances; we humans
release them into the ocean in unnaturally large amounts which can harm the environment.
Pollution, Concentration, and the Ocean
In general, pollution is more dangerous when there is
more if it, when it is more concentrated, because the
pollution is more likely to encounter something (e.g., a
body organ or tissue) where it can do harm. We are
surrounded by a large number of different pollutants all
the time in our daily lives (e.g., mercury, radioactive
substances), but the concentrations are so low that our
body is easily able to repair the damage or compensate. In
a sense, there is a “natural level” of pollution that we are
built to tolerate. Moreover, just about anything can be a
pollutant in high enough concentrations 1. (In other words,
you definitely can have too much of a good thing.) For
example, taking 2500 mg or more of calcium each day
makes it harder for your body to absorb other nutrients and
can damage your kidneys. Taking too much
acetaminophen (a pain reliever found in Tylenol and many Pollution on the Beach.
other products) is the leading cause of acute liver failure in Environmental Protection Agency.
the United States. Determining how much of a pollutant is harmful is difficult, because it can
take time for a pollutant to do its damage (it may happen a little bit at a time). Therefore, we
usually set safety levels that are very far away from the levels that we know can cause harm.
Just how far away they should be, though, is not always clear. For example, one of the first
environmental acts of the George W. Bush Administration was to allow more arsenic in drinking
water. It costs money to remove arsenic down to the current safety levels, and the administration
1
Too much vitamin A: blindness, liver damage, Too much vitamin B6: nerve damage;
Too much vitamin C: diarrhea & kidney stones; Too much vitamin D: kidney failure; etc.
Even drinking too much water (overhydration) can produce problems and even kill you:
look up water intoxication and hyponatremia for more information.
Oceanography 10, T. James Noyes, El Camino College
13B-2
argued that the “safety margin” was too large (that a “reasonably” safe amount was actually
much higher), so the money could be better spent on other things (education, health care, tax
cuts, the military, and so on).
Pollution dangers can often be minimized if the pollution can be spread out, reducing the
pollutant’s concentration. This actually makes the ocean a great place to dump our wastes,
because there are many mechanisms in the ocean which help break down and spread out
pollutants naturally. Recall that water is the “universal solvent;” it naturally dissolves 2 things
(pulls pollutants’ atoms or molecules away from one another). Waves and currents stir and mix
the ocean water, helping to move pollutants away from the place where they were dumped. In
doing so, they spread pollutants out, and thus reduce their concentration. Another reason that the
ocean is a great place for our wastes is that it is really big. This means that there are lots of water
molecules available to dissolve (pull apart and bond with) pollutant molecules and pollutants can
spread over a larger area (they can get farther apart from one another), reducing their
concentration. By spreading pollutants over a wide area, we say that ocean
water “dilutes” the pollution, weakens it, in much the same way that you
Is dilution
might add water (or ice, which melts into water) to an alcoholic beverage to
the solution to
“weaken” the drink.
ocean pollution?
O
O
O
O
O
O
O
P
O
O
O
P
O
O
O
O
O
O
O
O
O
P
O
P
O
O
O
O
O
O
O
O
O
O
P
O
O
P
O
O
O
O
O
O
O
O
P
O
O
O
O
O
P
O
O
O
O
After being dissolved:
O
Before:
O
The atoms or molecules of pollutants are strongly bonded together at first, but a group
of water molecules is even more electrically attractive than the neighboring pollutant
atoms/molecules. The water molecules pull the pollutant atoms/molecules away from
one another (i.e., they are less concentrated if they “spread out”).
1 tsp of salt
1 cup of water
Adding more
salt makes the
salt more
concentrated.
2
2 tsp of salt
1 cup of water
2 tsp of salt
2 cups of water
Adding more
water allows
the salt to
spread out,
reducing its
concentration.
This is crucial, because if the pollutants cannot be separated, then their concentration will remain high.
Oceanography 10, T. James Noyes, El Camino College
13B-3
The ocean’s size is absolutely essential: no matter how well water dissolves pollutants or how
strong waves and currents are, they can only do so much to reduce the concentration of
pollutants. For example, suppose that you dumped a bunch dye in a swimming pool and had
everyone swim in the same direction along the edge to create a “whirlpool.” The current would
help disperse the dye, and but at certain point the dye would spread as much as it could; no
amount of stirring and mixing could dilute it any further.
An example of how efficient the ocean is at naturally cleaning up our pollution
In the 1954, the United States moved the native inhabitants off the Bikini 3
Islands, and carried out the first test of a hydrogen bomb 4 on the islands and
surplus navy ships. Eventually the radioactivity naturally decayed enough for
people to return to the islands. To this day, you should not eat fruits and
vegetables grown on the islands, because they absorb radioactive substances
from the soil. The islands biggest industry is sport fishing – and fishermen get
to eat what they catch. Fish are abundant in the neighboring ocean, in part
because few people wanted to fish there for many years. They also take
advantage of the reefs created by the destroyed ships. Water’s ability to
dissolve solids (separate their atoms/molecules) and the waves and currents
have spread out the radioactive pollutants, so that the levels are no worse in
the Bikini Islands than anywhere else. The radioactive materials on land were
not taken away or spread out, so they remain a problem.
Bikini Atoll, NASA.
The ocean not only dilutes pollutants, but it can also bring them back to us or concentrate them at
high levels. For example, waves and currents bring pollutants to new locations. In the 1980s,
medical waste (e.g., used needles) washed up along some east coast beaches. Some things in the
ocean do not spread out or end up coming back to us because of density differences. Sewer pipes
may dump (treated) water miles from shore, but sewage may also float to the surface – where we
and animals are more likely to encounter it – because of its low density (it is too “fresh”). Thick,
dense sewage sludge sinks quickly to the bottom of the ocean, where it sits and festers, unmixed
or spread out by waves and currents (which are strongest near the surface), waiting to poison an
animal that we might eat. I should also note that even though the ocean is big, it is not infinite.
At some point, it will reach its “holding capacity,” and will not be able to take any more 5, just as
at some point, the water in the seawater lab could not dissolve any more salt 6.
3
A historical side note: The swimsuit called the “bikini” was unveiled in France during the same week that the
bomb was exploded, and the designers named it after the event to gain more publicity. I guess that it was an equally
explosive event for the male libido.
4
A hydrogen bomb is much more destructive than the atomic bombs that were dropped on Hiroshima and Nagasaki
during World War II. In atomic bombs, highly-concentrated uranium atoms split (break apart and fly away from
one another). They run into and destabilize nearby uranium atoms and cause them to split. This happens again and
again in a runaway “nuclear chain reaction” in which the atoms fly apart at tremendous speeds. In hydrogen bombs,
an atomic bomb is used to generate temperatures and pressures high enough to cause hydrogen atoms to start fusing
together as they do inside the Sun. This releases a tremendous amount of energy, and is why the Sun keeps shining.
Thus, our most devastating modern nuclear weapons essentially create mini-Suns or stars on the surface of the Earth.
5
To my knowledge, there is not a good ocean example of this. However, the same arguments have been made for
polluting the atmosphere (e.g., it is big, has good mixing mechanisms), and therefore I suppose some people were
surprised when acid and mercury tainted rain began falling from the skies: the atmosphere had reached its “limit” for
holding on to them.
6
Remember: once water molecules are bonded with one atom, they cannot bond with (“dissolve”) other atoms.
Oceanography 10, T. James Noyes, El Camino College
13B-4
In addition, toxins often work their way up ocean food chains,
allowing them to harm us when we eat seafood (e.g., pregnant
women should limit their intake of seafood or risk giving their babies
mercury poisoning). Toxins in the ocean are accidentally absorbed
by small ocean organisms like plankton, lots of which are eaten by
larger animals. The more an animal eats, the more toxic it becomes.
(This is called bioaccumulation.) In addition, a predator gets an
Clam
entire lifetime of its prey’s accumulation of toxins in each gulp.
Since a predator eats a lot of its prey, it has a lot more toxins in its
body than its prey. Thus, animals at the top of the food chain have a
lot more toxins in them than those at the bottom. (This is called
biomagnification. By the way, where are you in the food chain, at the top or bottom?) Fatty
tissues are particularly effective at retaining many dangerous toxins, so you should avoid eating
them. (Put down that whale blubber sandwich!)
Chemical Cocktails All Around Us
More and more studies are showing that chemicals that are safe individually are dangerous when mixed.
(Some students are like this. Individually, they are fine, but if you let them sit next to one another, you’re
asking for trouble in the classroom.) For example, Tyrone Hayes of U.C. Berkeley has found that
individually fungicides and insecticides commonly used in the United States have no effect on frogs at
low concentrations (0.1 part in a billion). However, at these same low concentrations in combination, the
adult frogs are smaller and more susceptible to certain infections. There is evidence which suggests that
low-level pollution effects are already being seen in humans 7, particularly in rural farming communities
which use the chemicals on their crops (the chemicals are washed from their crops into their water
supply). More and more studies are being done on the effect of chemicals in combination. However, it is
much harder to make good regulations for chemicals in combination, because you have to perform a lot
more tests. For example, suppose you have only 3 chemicals to test, A, B, and C. In addition to 3 tests
(A, B, C individually), you have to also test all the combination too: AB, BC, AC, ABC, 7 tests total.
What if we add one more chemical, D? Then we have to perform 8 more tests (D, AD, BD, CD, ABD,
BCD, ACD, ABDC), twice as many even though we only added 1 new chemical! Now consider the
really scary fact: there are tens of thousands of chemicals that we have made and released into the
environment.
7
For example, lower male fertility.
Oceanography 10, T. James Noyes, El Camino College
13B-5
EXAMPLES OF OCEAN POLLUTION
In the next sections, we will
examine specific examples of
ocean pollutants.
By the 1960s, DDT reduced nesting
bald eagle population to 417.
They were finally taken off the
endangered species list in 2007.
DDT, PCBs, and Mercury
DDT, PCBs, and mercury are examples of chemicals that are among the
most common and dangerous ocean pollutants. DDT is a pesticide that
was commonly in use in the United States until the 1970s, by which time
its dangers had been realized. It washed off crops, down rivers, and into
DDT harmed
our local pelicans.
the oceans where it bioaccumulated (e.g., passed up the food chain). In
one famous example, the population of brown pelicans in southern California dropped rapidly
when high DDT concentrations in their food caused their eggs to break 8: mother birds were
sitting on and crushing their babies. The Montrose plant in Torrance (and others) dumped their
wastes into the local sewer system from the 1940s until the 1970s. DDT and other chemicals
entered the ocean south of Palos Verdes, and lots of them are still present in the local sediments.
As a result, we have a large ocean “superfund 9” site in the United States, right here along our
coastline. Government agencies and environmental groups try to warn fishermen and the public
not too catch, sell, or eat certain kinds of fish, particularly those that eat worms and other animals
that might have been living in toxic mud. They are also told to avoid eating fatty tissues, which
are more likely to have the toxins in them. Recent measurements by the Environmental
Protection Agency (2009) suggest that DDT and PCB levels have dropped by 90% in the
sediments since the last sampling five years before, much faster than the 1-2% per year that had
been measured previously. However, levels in ocean life have not gone down much at all. Where
much of the DDT has gone – and why – is still unclear. Since only a few samples were taken (to
keep down costs), perhaps they just happened to take samples in spots with low concentrations.
Palos
Verdes
Worst
Contamination
8
Controversially, DDT is still
used in some places to kill
malaria-causing mosquitoes.
Some people think pollutionrelated illnesses are worse than
widespread malaria, others
disagree.
DDT contaminated sediments in
southern California. Red, orange,
and yellow indicate higher levels of
DDT. Environmental Protection
Agency.
DDT is a “calcium inhibitor.” It weakens the calcium carbonate in the egg shells.
“Superfund” is the nickname for the law (CERCLA, 1980) that allows the Environmental Protection Agency
(EPA) to identify and assess places with chemicals that are dangerous to human health and the local environment.
The EPA has ranked how dangerous each place is, and prioritizes getting the most dangerous places cleaned up.
The fact that it is a Superfund site indicates that this area is one of the most polluted patches of the ocean
in the entire United States.
9
Oceanography 10, T. James Noyes, El Camino College
PCBs are a family of chemical compounds that are
difficult to break down. This made them valuable in
many products 10, particularly as insulators in electronics,
but it also makes them dangerous pollutants, because they
break down into their harmless components very slowly.
Unfortunately, PCBs potential for harming people was
not realized until decades after their widespread use and
the unrestricted dumping of products containing them.
Known health problems among humans include liver
damage and a painful and disfiguring skin disease.
Perhaps the most interesting aspect of PCBs in the ocean
is how widespread they are. Even though products were
dumped primarily in developed countries, PCBs are a
problem for many animals who live near the Poles, thus
showing how effective the ocean and atmosphere are at
spreading out pollutants. For example, bioaccumulation of
PCBs has caused female polar bears to develop male
genitals 11. Studies of people who live in the Arctic and eat
pilot whales have shown that PCBs appear to reduce the
effectiveness of vaccines against illnesses like tetanus.
13B-6
The (fatty) blubber of animals who live
near the Poles like this beluga whale are
good at bioaccumulating pollutants.
NOAA/Marine Mammal Commision.
My final example of a dangerous chemical in the ocean is
mercury. Like DDT and PCBs, mercury becomes
dangerous in the ocean via bioaccumulation: some bacteria use
mercury for a process like chemosynthesis, and then are eaten
by zooplankton or release the mercury into the water where it
can be absorbed by phytoplankton (and other organisms).
However, unlike DDT and PCBs, mercury is not a man-made
substance, so we do not harm the environment by making
mercury, but by releasing mercury in unnaturally large
quantities into the environment. Mercury is used in several
industries, and often released into the atmosphere via
smokestacks that are burning coal. The mercury is then
washed out of the atmosphere when it rains, where it gets into
soil and the ocean. Mercury can cause neurological disorders:
A few of the many possible effects include blindness, brain
damage, and birth defects. Some people are unable to control
their own bodies: they might shake uncontrollably or become
paralyzed. An example of what the disorder might do to
someone is the “Mad Hatter” from Alice in Wonderland whose
character is based on real-life hatters 12 who tended to become a
little “crazy” from mercury-poisoning back in Victorian
England.
10
According to a Food and Drug
Administration study (FDA),
human flesh is unfit for
consumption, because the
concentration of pollutants
is too high (bad news for
cannibals). Like other top
predators, we get a large dose
of pollutants in the foods we eat.
If you eat shark, then the mercury
in its tissues may allow it to bite you
back. NOAA, DOC.
Other products include rubbers and paints. PCBs also have been used as a flame-retardant in oils.
There must be some pretty confused bears up the Arctic.
12
Hatters making felt hats worked too closely with mercury. We just didn’t know any better back then.
11
Oceanography 10, T. James Noyes, El Camino College
13B-7
A Fishy Ruling
In the early 2000s, California’s attorney general, Bill Lockyer, tried to enforce Proposition 65,
which required manufacturers to post warnings about mercury on cans of tuna. As you might
imagine, manufacturers resisted, and in May 2006 a judge agreed with the manufacturers that
since mercury occurs naturally in the ocean and federal and state governments post guidelines,
consumers are adequately protected. (The judge’s ruling makes perfect sense, right? You visit
the FDA and EPA websites all the time to stay up-to-date about these issues, I’m sure, and will
not mind if naturally-occurring mercury in the manufacturer’s product harms your child.) The
attorney general’s office claimed that the ruling will hurt poor women (and their children) who
do not have easy access to the internet or good health care.
Eating Fish and Other Seafood:
Some Recommendations
Eating fish is an important part
of a healthy diet. Most fish have
omega-3 fatty acids (good for
your heart) and are low in
saturated fats, making them
an excellent source of protein.
However, to reduce the risk of
Eating organisms lower
mercury-related diseases (e.g.,
on the food chain is
safer (less bioaccumudamage to hearing, hand-eye
lation, fewer toxins).
coordination, learning ability and
more) in their children, pregnant
women should probably avoid eating fish. Young children should have no more than 1/3 of a
(solidly-packed) can of tuna per week, and women who may become pregnant should not eat
more than 1 (solidly-packed) can per week. (You want to keep the levels in your body down if
are thinking about having children anytime in the near future, say within the next couple of
years. About 10% of women of childbearing age have mercury levels above those considered
safe by the EPA.) Examples of seafood which typically have low levels of mercury include
salmon, shrimp, clams, tilapia, crab, and scallops. (Eat up to 12 oz. a week. Fish sticks and fish
sandwiches are made from low-mercury fish.) The FDA recommends avoiding large, predatory
fish like shark, swordfish, tilefish, and king mackerel. Albacore light tuna typically contains
more mercury than light tuna.
When the Superfund Law is Not Superfun
According to the Superfund law, the EPA can force polluters to clean up their mess, but in some
cases – like Palos Verdes – there is so much pollution that the original polluters cannot afford to
clean it up: If the government tried to make them do so, then the polluters would immediately go
out of the business, and the pollution would not get cleaned up. Thus, the government (i.e., our
tax dollars) has to the clean up most of the mess one way or the other, and polluters – if they are
still in business – have to contribute a “reasonable” amount.
Oceanography 10, T. James Noyes, El Camino College
13B-8
Plastics
Plastics have been called a man-made “miracle” substance.
Just think of all the items around you that are made out of
plastic: pens, pencils, computer keyboards, combs, binders,
car dashboards, cups, straws, action figures, and much, much
more. Plastics are great because they can easily be molded
into a wide variety of forms and are strong, durable, lightweight, and cheap to manufacture. Thus, you can make
nearly anything out of them, the object will last, it will be
easy to carry, and everyone can afford to buy what you
make. These advantages are precisely what make plastics a
NOAA
dangerous ocean pollutant. (Some people consider plastic to Plastic pollution. Plastic bag on coral.
be the worst ocean pollutant.) Since they are lightweight,
plastics have a low density and thus float at the surface of the ocean Small plastic particles are
making up a larger and larger
where most ocean life is found. Plastics are strong and durable, so
part of our beach sediments.
they do not break down easily or become soft. Many animals like
Perhaps this is the solution to
seals, sea turtles, and sea gulls are strangled by or choke on plastics, our beach erosion problems?
presumably mistaking them for the transparent jellies that they
About 1 in 6 plastic water
normally eat. Their dead bodies contain stomachs full of plastic
bottles are recycled. In the
products. When the dead bodies decompose, the plastic is released
next 10 years, people will
back into the environment to kill again. Plastics do slowly break
throw away enough plastic
water bottles to cover the
down over time, especially when exposed to sunlight, and become
entire coast of California 6small particles. However, plastics have a tendency to absorb toxic
inches deep and 20-feet wide.
ocean pollutants including DDT and PCBs, so these tiny plastic
particles may cause even more harm to ocean life through bioaccumulation than large plastic
products do by choking animals. Tiny plastic particles are eaten by animals filter feeding
plankton from the ocean: the more the animals eat, the more toxins build up in their bodies – and
in the bodies of predators who eat them. Plastic also takes up space in animals’ stomachs, so it
interferes with their ability to take in and digest their food. Since plastic products are cheap to
make, lots are made, lots are bought, and people don’t worry about throwing them away, since it
is cheap to buy more. Thus, a lot of plastics end up getting washed down storm drains and into
the ocean, and organisms are more likely to encounter and eat them.
Almost every bit of plastic that we have made still exists 13. Where has all
the used plastic gone? A great deal of the plastic litters the land or ended
up in landfills, but a large amount has also congregated in the center of
the ocean gyres 14, pushed and held there by the prevailing surface winds
and ocean currents. People who sail through these waters see plastics
floating on the surface as far as the eye can see in every direction. In
these places, the amount of plastic is 6 times heavier than the amount of
plankton. In the North Pacific Ocean, plastic debris covers an area twice
the size of Texas.
13
A very small amount has been incinerated.
Most ocean pollution is found near the coasts, because most pollution is
washed off the land, including plastics. That being said, plastics are becoming
a major exception to the rule that most pollution is found near the coasts.
14
National Oceanic
and Atmospheric
Administration (NOAA),
Dept. of Commerce
Oceanography 10, T. James Noyes, El Camino College
13B-9
Marine Debris from
Tern Island. Ocean
winds and currents cause
a lot of our discarded
wastes to collect in the
middle of the ocean
where they pollute the
beaches of small islands
far from the continents.
USFWS Hawaiian
Islands, NWR.
Many ocean animals are
strangled by fishing nets
that are thrown away.
This is called “ghost
fishing.”
Oil
When people are asked to think of an example of ocean
pollution, often the first thing that they think of is an oil
spill. Ironically, some scientists consider oil to be one of
the least harmful ocean pollutants, because oil is a
hydrocarbon 15: it is a “fossil” fuel, and thus was originally
a carbohydrate in a living organism. In other words, oil is
a natural substance that is biodegradable (for example, it
is the source of energy for some chemosynthetic bacteria).
Humans have only caused the amount of oil in the ocean
Tar on our local beaches. Petroleum
to nearly double its natural level, mainly because of oil
naturally leaks out of the bottom of the
leaking from our cars and other machines that is washed
ocean long our coast.
into the ocean (not oil spills). Oil, natural gas, tar, and
other petroleum products naturally leak from the bottom of the
The amount of oil washed
ocean in many places – including southern California – and support
off the land and into the
chemosynthetic communities of organisms. (See topic 10B, Deepocean each year is equal
Sea Life, for more information.) Most of the oil in the ocean (over
to about 17 Exxon Valdez
(a large tanker) oil spills.
60%) has leaked naturally from the ocean bottom.
Of course, oil spills do cause tremendous harm to ocean
life 16. Lots of algae, animals, and plants quickly die after
being coated with oil. Oil ruins the insulating feathers and
fur of marine birds and mammals, so they become too cold
Oil is an example of a natural
substance that humans introduce
into the environment in
unnaturally high concentrations.
15
Carbohydrates have 1 water molecule per carbon atom. The oxygen atoms are removed to make it into a
hydrocarbon. You can see how the word “hydro-carbon” is the word “carbo-hydrate” reversed.
16
In 1969, the death and destruction produced by the “blowout” of an oil platform near Santa Barbara helped inspire
many of the first environmental organizations in the United States. The public reaction led to President Nixon
signing the bill that founded the Environmental Protection Agency (EPA). For more information, see the link in the
website section of the course website.
Oceanography 10, T. James Noyes, El Camino College
13B-10
Exxon Valdez (1989).
and die. Some animals are poisoned by ingesting the oil.
Notice the “booms”
The toxic compounds mixed in with the oil often hit
(long, white lines):
they are used to try
plankton the worst, killing both the plankton at base of the
to keep the oil from
food chain and the eggs and larvae of large animals: an
spreading. NOAA.
entire generation can be lost. However, most populations
begin to rebound within a few years, and within 10-20
years the environment will have pretty much recovered.
The major exception is beaches; toxic oil remains among
the sediments for many more years to come. Unlike the
open ocean, waves and currents have great difficulty
spreading out the pollution within the sediments of the
beach (and thus making it less harmful). Humans have
just as much difficulty cleaning up beaches after oil spills
as nature does. Our best cleaning tools – scalding-hot
water from high pressure hoses and harsh chemical
cleaners – are very effective at cleaning the sediments, but
they also kill the surviving algae and animals, essentially
sterilizing the beach. In some cases, beaches that were not
cleaned by humans have recovered faster than beaches that were cleaned! So, it is very
important to keep oil spills from reaching the shoreline; doing so can save a vast amount
of time and money on clean up efforts and reduce the time for the environment to heal.
Deep Horizon Oil Spill (“BP Oil Spill”, 2010). Pictures from the US Coast Guard (left) and NASA (right).
Oil Pollution. National Oceanic and Atmospheric Administration, Department of Commerce.
Oceanography 10, T. James Noyes, El Camino College
To keep oil from reaching land, we use
Booms protecting islands. US Navy
“booms” and “skimmers.” Booms are
long, thin, floating barriers. Since oil
floats, booms can block oil. However,
waves can push oil over booms, and harsh
winds and waves can sink them. We also
“skim” oil off the surface: Typically, oil is
collected using booms and then rotating
plastic drums or discs are inserted into the
oil. The oil sticks to the specially-designed
or treated plastic and is brought onboard,
scrapped off, and the drums or discs are
reinserted to skim more oil. If weather conditions are
right, the oil is simply lit on fire to burn it away.
“Dispersants” can be added to the water to break up
the oil, much as you use soap to get oils and grease off
your dishes. This allows the oil to spread out into
smaller toxic pieces that will do less damage to ocean
life, and also allows the oil to sink deeper, away from
the surface where most ocean life lives. However,
these dispersants are also toxic to ocean life, and for
this reason they are not introduced down deep where
there are few waves and currents to spread them out,
because they are more likely to stay concentrated and
make the bottom sediments toxic. Controversially, the
company BP added dispersants deep in the ocean to try
to reduce the damage being caused by oil rising up
from the ocean floor from the Deepwater Horizon oil
spill (2010). The company argued that adding
dispersants would keep concentrated oil from reaching
the surface, and thus reduce damage to the life at the
surface at the ocean. Their critics pointed out that it
would also mean less oil at the
surface for cameras to record,
Adding Dispersants.
US Air Force.
and that the oil and dispersants
would remain down deep and
cause damage for a much longer
period of time than if they
reached the surface – but the
damage would happen where
few could see or record it.
13B-11
Skimming.
US Coast
Guard
Oceanography 10, T. James Noyes, El Camino College
13B-12
A fast response to an oil spill will greatly reduce its harmfulness and make it much cheaper to
clean up. The “lightest” parts of oil evaporate away within a few days at most, leaving behind
“mousse:” a thick mixture of oil, air, water, and anything in the ocean water. Skimming,
burning, and dispersants are much less effective on mousse. This is why oil companies are
suppose to have emergency plans and clean-up equipment nearby before they start drilling.
Oil Mousse. Courtesy of Leslie Gordon, USGS.
Pelicans covered in oil. Deepwater Horizon (BP) oil spill.
Courtesy of the International Bird Rescue Research Center.
CC Attrib. 2.0 Generic.
Bioremediation
One interesting method of cleaning up oil spills and other forms of pollution is bioremediation.
Bioremediation is using living organisms to clean up pollution. For example, geneticallyengineered plants are being developed do soak up mercury from soil and lakes, keeping it from
getting washed into the ocean. The plants can then be harvested and properly disposed of. In the
case of oil, chemosynthetic bacteria that live off of oil can be introduced in the area of the oil
spill. In principle, they will multiply quickly, decompose (“break down”) the oil, and then die
off or go dormant when their task is done. Research on beaches in Scotland (it is near the North
Sea where there are lots of oil rigs) have shown that beaches recover from a second oil spill
faster than the first, presumably because of dormant bacteria that originally came to the beach
after the first spill. When sand from a beach that had recovered from an oil spill was
transplanted to a beach which had never endured an oil spill, researchers showed that it helped
“vaccinate” the pristine beach against a future oil spill.
Oceanography 10, T. James Noyes, El Camino College
13B-13
Sewage and Storm Drains,
Beach Closures and Harmful Blooms
In the movie Find Nemo, the characters repeat
the line “All drains lead to the ocean” again
and again. They are right, but there are two
different systems which carry our water to the
ocean: the sewer system and the storm drain
system. The sewer system includes the pipes
that are connected to the drains in your home:
the kitchen sink, the bathroom sink, the toilet,
National Oceanic and Atmospheric Administration,
the bathtub, the shower, the washing machine,
Department of Commerce
etc. The used water from these drains goes to
a sewage treatment plant where materials are
When it rains, extra water goes down drains
separated out according to their density,
that are connected to the sewage system, and
“broken down” using chemicals and bacteria,
if the rainfall is heavy, water can start to back
and sterilized (e.g., using chlorine) to kill any
up in the sewage treatment plant. Sometimes
remaining bacteria (which might cause illness).
the plant has to release untreated water into
The resulting solid materials are rich in
the ocean to avoid getting flooded!
nutrients and often sold as compost, and some
treated water is used by golf courses, parks, and others. (Most people do not like the idea of
using treated water in their gardens or homes, but I am told that it is actually quite safe.) The rest
of the treated water and disinfected material is released into the ocean, typically miles from shore
via long, underwater sewer pipes.
The Clean Water Act
In the past, sewage did not have to be treated so extensively, so many coastal waters
and estuaries near cities and industrial plants were heavily polluted. Since the Clean
Water Act of 1972, sewage treatment plants have been required to improve the
quality of the water that they release to a much higher standard, and sewage sludge –
nearly untreated solid materials rich in chemicals – is no longer being dumped along
the coasts of the United States. (Most cities in the developing world discharge
untreated sewage directly into rivers and the ocean.)
Agriculture
In addition to untreated sewage and storm drains, farming can also add large amount of
nutrients to the ocean. Farmers put lots of artificial fertilizers on their crops, helping them
grow more food per acre. However, large amounts of these nutrients are washed off the
fields and into rivers which carry them to the ocean. In addition, big-business agriculture
involving “industrial” production of livestock (e.g., cattle, pigs, chickens) generates vast
amounts of manure, which often gets washed into nearby lakes and streams when it rains.
From Sweet Tea to Sweet Sea
Sewage treatment does not remove all chemicals from wastewater. For example, sucralose, the
artificial sweetener in Splenda, goes through your body without being altered and is excreted. It
then goes through wastewater treatments plants and is also not affected by the treatment process.
Oceanography 10, T. James Noyes, El Camino College
13B-14
You can see storm drains everywhere along the sides of our streets. Since rain water cannot soak
into the ground 17 anymore (because we have paved over so much of the land of our cities), the
job of storm drains is to get rain water off our streets as quickly as possible so that that water
does not make driving dangerous or flood our homes and businesses. The rain water also picks
up animal feces 18 and other materials (e.g., yard wastes like dead leaves and grass, oil drippings
from cars, arsenic left behind by car tires, various heavy metals, fertilizers and pesticides from
landscaped areas) which are washed directly into the ocean. In the past, these materials were
typically “filtered” out of the runoff by forests and wetlands. Bacteria on the fecal material 19 can
cause beachgoers to get sick (liver, breathing, and stomach problems; ear and eye infections;
hepatitis; paralysis). The ocean helps the bacteria get into our bodies through our eyes, ears,
mouth, etc.: the water offers support to the bacteria so that they can drift to us.
Most of the ocean’s nutrients are not added
by humans. They enter the ocean naturally.
Storm Drains by the side of the road lead directly into the ocean.
85% of beach closures occur because
of unacceptably high levels of fecal
bacteria in the water. According to
the EPA, if a beach has the maximum
acceptable amount of bacteria (for the
beach to stay open), about 2% of
swimmers (1 in 50) will get sick.
Local officials must wait a day or two for the results of water tests. During this
time, beachgoers may be exposed to harmful bacteria and substances. Moreover,
the surf zone is extremely turbulent, so by the time the test results are in, waves
and currents may have moved significant amounts of pollutants to other beaches.
17
Soaking into the ground is not necessarily a good thing anymore, because the water can pickup chemicals that can
poison our water supply. In addition, groundwater in aquifers can move from the land into the ocean, so it is another
route by which chemicals can enter the ocean.
18
The animal feces come from both pets and wild animals.
19
Note that it is bacteria from land animals that typically make human swimmers sick.
Most ocean bacteria are not well adapted to invade that bodies of land mammals like humans.
Oceanography 10, T. James Noyes, El Camino College
13B-15
Coastal Development
It is estimated that about 1,500 new homes are built along the coastline of the United States each
day. Right now, more than 50% of our population lives in coastal counties 20 (that cover 17% of
the land in the lower 48 states), so that does not even count the population of the counties that are
just a little bit inland like San Bernadino and Riverside. Coastal populations are increasing fast:
they are expected to grow by over 30% between 2000 and 2020. As we pave over more land and
more people generate more wastes than before, we can only expect more ocean pollution
problems in the future.
20
This is true throughout the world. You can tell that most people in the United States live close to the coast from
the presidential election results in 2000 and 2004. In 2000, both Bush and Gore got about 48% of the vote, with
Gore getting about ½ million more actual votes (as opposed to votes in the electoral college). In 2004, Bush got
51% of the vote, and Kerry got 48% of the vote. Thus, in both races about half of the people voted for the
Republican candidate and half voted for the Democratic candidates. If you look at the electoral maps, though, you
will see that most of the country looks pretty red (Republican), except for the west coast, New England, and the
states bordering the Great Lakes. Thus, even though “red” covers more than twice the area covered by “blue,” its
population is not any larger; well over half our population has to be living near the coast.
Oceanography 10, T. James Noyes, El Camino College
13B-16
Harmful Blooms
Offhand, you might expect that causing blooms is a good thing: more nutrients leads to the
growth of more phytoplankton which means there is more food for animals and ultimately for us.
However, as we have dumped more and more nutrients into the ocean, we have found that they
can also encourage the growth of harmful microorganisms. Some can attack fish and other
organisms directly, causing wounds (e.g., Pfisteria piscicida), or inhibit feeding and/or breathing
(produce lots of mucus, get stuck in gills, e.g., species of Chaetoceros), but many harm other
organisms and the environment “by accident.”
“Red tides” are a classic example. Red tides are a bloom of red-colored
phytoplankton 21 (typically dinoflagellates); there are so many
phytoplankton in the water that they make the water look red (or brown
or yellowish). Some red tide algae – but not all! – produce chemicals 22
that are toxic to vertebrates like birds, mammals, and humans. Filter
feeders (or suspension feeders) like clams and other shellfish strain the
algae out of the water during a bloom. They eat lots of algae, and the
more they eat, the more toxic they become. (This is called
“bioaccumulation” or “biomagnification.”) If we or other vertebrates eat
the shellfish, we can become sick. Illnesses caused by toxins
being passed up the food chain in this way include ciguatera fish
poisoning (CFP), diarrhetic shellfish poisoning (DSP), and
paralytic shellfish poisoning (PSP). In general, though, it is safe
to swim in red tides, because you will not swallow nearly enough
water to become poisoned 23. However, the algae do leak toxins
into the water, and these cause some people to develop rashes.
As long as you get out of the water when you notice the rash and
wash it off, you should be fine. Breaking waves can catapult
these toxins into the air, and some of these toxins cause
respiratory (breathing) problems for people who live near the
coast.
Clam
Red Tide, La Jolla California.
Courtesy of P. Diaz
(Public Domain)
21
Red tides have nothing to do with the tides or the Moon.
The classic example is domoic acid. Domoic acid mimics a molecule in our brains that is needed for neurons to
fire. It essentially makes our neurons fire continuously, causing spasms, hallucinations, etc.
23
In fact, I expect that the salt water would be worse for your body than the amount of toxin that you swallow.
22
Oceanography 10, T. James Noyes, El Camino College
13B-17
In general, eating fish is safe so long as it was fighting and kicking when you caught it.
Just be safe, eat the fillets, not the organs or entrails. The most dangerous organisms to
eat are filter feeders like clams, mussels, oysters and so on, because they are more likely
to build up lots of toxins in their systems. It should be safe to eat them in restaurants,
because the United States has good regulations and does a good job of inspecting
seafood. Restaurants will import shellfish if the local ones may be poisonous.
Another example of a harmful algae bloom is a “dead zone 24.” At the end of the bloom (once the
phytoplankton have used up all the nutrients), the water will be filled with a lot of dead
phytoplankton. This encourages the growth of bacteria who decompose (“breakdown”) the
bodies. In doing so, the bacteria use up the oxygen in the water. Animals that do not swim away
(either because they cannot swim or because they cannot survive in the open ocean), die because
they cannot breathe.
One of the best known examples of a “dead zone” is the one that occurs at the end of the
Mississippi River. The Mississippi drains practically the entire middle of the United States,
including a vast amount of farmland. The fertilizers (nutrients) that the farmers put on their land
help them grow more food per acre, but a lot are washed off their land and into rivers which
carry them into the ocean. The resulting “dead zone” harms the livelihoods of the fishermen.
Harmful algae blooms cost the United States an estimated $100 million dollars each year in lost
fisheries and tourism revenues 25.
End of the Mississippi River, NASA
National Oceanic and Atmospheric Administration,
Department of Commerce
24
Scientists use the word “eutrophication” to describe this phenomena, and the word “anoxic” (“no oxygen”) to
describe the lack of oxygen in the water.
25
The Port of Los Angeles contained many “dead zones” in the 1950s. The Clean Water Act limited the amount of
pollution that could be dumped in the harbor, and since the mid-1980s there have not been any more dead zones.
Oceanography 10, T. James Noyes, El Camino College
13B-18
More About Dead Zones
“Dead zones” are most common near developed countries whose industries and cities (raising huge
number of animals like cattle for food, intensive farming, dumping sewage) add large amount of nutrients
to the ocean (e.g., the amount of nitrogen in the ocean increased by about 80% from 1860 to 1990).
Examples of places with “dead zones” include the Black Sea, the end of the Mississippi River,
Chesapeake Bay, and the coast of Oregon.
Low oxygen conditions are usually worst on the bottom. Dead, decaying material sinks to the bottom,
and the bacteria remove oxygen from the water as they decompose the dead bodies. In addition, in
shallow coastal waters, the abundant phytoplankton near the surface block sunlight from reaching the
bottom where macroalgae (seaweeds) live. The macroalgae die; instead of adding oxygen to the water
near the bottom, their decomposing bodies help use up the remaining oxygen. If the density difference
between the bottom water and surface is too high, waves and tidal currents will have difficulty bringing
oxygen-rich surface water down to the bottom. Thus, global warming may be making “dead zones”
worse: it keeps the warm surface water from mixing with cooler, deeper water. In addition, warm water
cannot “hold” as much oxygen as cold water 26, so more oxygen is given to the atmosphere and less mixes
downwards. This may be one of the reasons that “dead zones” are becoming larger and more common,
and that oxygen levels below the surface are dropping in the Pacific Ocean.
Zooplankton (e.g., copepods) cannot eat all the new phytoplankton; there are simply too many. Moreover, phytoplankton can reproduce much faster than zooplankton, so while the zooplankton population
grows too, zooplankton cannot keep the phytoplankton from becoming dangerously overpopulated.
Brief, strong winds are becoming more common along the coast of Oregon. They produce brief, strong
upwelling events followed by brief, massive blooms of phytoplankton. Since zooplankton cannot eat
them all, many dead bodies sink deep into the ocean. Bacteria “bloom” as they decompose the bodies and
in doing so use up all the oxygen in the deep waters, killing many of the animals who live there.
Many species of “jellies” can tolerate low-oxygen water,
so they can grow more abundant in “dead zone” and
displace fish or other organisms in the food chain. Some
biologists call these jellies “dead end species,” because
many fish and other predators that we like to eat cannot
live off the jellies.
One major example of the restoration of a “dead zone”
demonstrates that it is best not to let the “dead zone”
become large and widespread in the first place. With the
collapse of communism (c. 1989), many eastern European
economies collapsed as well, so fewer nutrients entered the Black Sea, and its dead zone became smaller.
The recovery of ocean bottom has been very slow: the animals (e.g., fish) that once lived there did not
simply “bounce back” when conditions became better. The new dominant species, jellies (an invasive
species is one of the worst – see the next section), eat plankton – the fishes’ food – and the fishes’ eggs
and larvae, keeping fish populations from growing quickly or at all. Scientists call this a “regime shift”
from a population of organisms that we like to eat to a population of organisms that we do not like to eat.
Unfortunately, the new, jelly-dominated “regime” is quite stable: things are not going to change back to
the way they were without a major disturbance.
26
Warm (fast-moving) water molecules form weaker bonds, so warm water cannot hold onto as many oxygen
molecules as cold water can.
Oceanography 10, T. James Noyes, El Camino College
Invasive Species 27
If you think about it, there are 3 things that can
happen when a foreign species is introduced into
a new environment:
13B-19
Invasive species are not really an example
of pollution, but are an example of how
human actions and negligence can harm
an ocean environment.
• It will die out: it is quickly eaten (it is an exotic “snack” for the locals), cannot find food
(nothing looks appetizing), have no one to reproduce with (nobody’s here but us guys), etc.
• It will be able to survive and become a new member of the environment.
• It will be “better” than the native species (e.g., at finding food, won’t have any predators)
Almost all introduced species will die out, but a few will fall into the last category; its
advantages will allow it to “take over” the environment where it was introduced, and the native
species begin to die out. Invasive species can arrive in a new place on their own, but nowadays
humans are carrying more and more with them as we quickly and easily travel the globe.
Sometimes we even introduce new species intentionally, thinking that we will make a place
better. So many foreign species have been introduced to San Francisco Bay, intentionally and
unintentionally, that it almost entirely contains foreign species; we don’t even know what it was
originally (“naturally”) like.
There are many examples of aquatic invasive species, but I will only discuss three. Toxic
dinoflagellates (a kind of phytoplankton, some of which cause red tides) have been transported
from estuary to estuary, presumably by ballast water (see below), and have poisoned the food
chain in their new homes via bioaccumulation. Probably the most famous example of an aquatic
invasive species is zebra mussels, a kind of mollusk (clam-like animal) that grows on hard
surfaces like rocks. The zebra mussel was introduced to the Great Lakes from Europe in the
1980s, and spread quickly since it has no natural predators. It has killed native species by
growing over them, taking the space where they want to live, or eating lots of plankton, causing
native species to starve. In addition, they grow everywhere, clogging all kinds of pipes (e.g.,
storm drains, sewer pipes, power plant inflow and outflow pipes). The United States spends over
$100 million per year scrapping them off, a breathtaking amount – and waste – of money.
Zebra mussels. Single mussel (left, USGS) and growing over every surface (right, NOAA).
27
Invasive species are also known as “alien” or “exotic” species.
Oceanography 10, T. James Noyes, El Camino College
13B-20
In southern California we have our own invader: caulerpa taxifolia, a fast-growing tropical
seaweed that has caused havoc in the Mediterranean Sea already. Caulerpa taxifolia pushes
aside native algae, and local animals do not eat it, so it just spreads and spreads. It is a popular
decoration in aquariums, and it is thought that it was introduced along our coast when someone
dumped their aquarium in the ocean. Caulerpa taxifolia was found in San Diego and Orange
County in 2000, but fortunately, our (expensive) efforts to get it under control appear to be
succeeding, thus preserving the food supply for native species.
Caulerpa Taxifolia. Public Domain.
Marine invasive species are most commonly
carried from place to place in the ballast
water of cargo ships. Ballast water is water
Ballast Water
that is pumped into a ship from the ocean
when a ship is not fully loaded. The water weighs the ship down so that it does not tilt when one
end or side of the ship is unload, it does not rock back and forth too much, it is at the right height
to be unloaded by cranes on land, and its propeller and rudder are at the right depth for
maneuvering. The problem is that the ballast water may contain lots of plankton, and if they
survive the trip, they may be pumped out into a foreign estuary, and “take over.” Scientists have
worked on a number of systems to kill animals in ballast water (the main concern with this
“solution” is that the poison will get released out into estuaries with the ballast water, and poison
native animals and our food supply). A simple solution is to require ships to dump their ballast
water in the middle of the ocean and take on new ballast water out there as well. Unfortunately,
this costs time and money (fuel to get the huge cargo ship going and to bring it to a stop), so
most ship owners are unwilling to do it. Local communities like our own have no right to make
them do so, because only the
federal government can make rules
about interstate and international
commerce. In 2004, the George W.
Bush administration finally
abandoned its use of voluntary
guidelines (only about 30% of
ships were complying) and
instituted mandatory regulations
with fines ranging up to $27,000.