Ocean
acidification is occurs as the pH of the ocean ecosystem decreases. The primary
cause of the acidification is deposition of carbon dioxide from the Earth’s
atmosphere. Atmospheric carbon dioxide deposition is one of the most preventable
causes of ocean acidification due to the fact that it is almost entirely caused
by humans. Acidic ocean waters are detrimental to the marine ecosystem. The
acidic waters break down calcium carbonate in the ocean waters that primarily
exists in corals and shells of marine animals. The breakdown of calcium
carbonate will kill these animals, destroying the marine food web from the base
up. Prevention of ocean acidification through atmospheric carbon dioxide is
absolutely critical in order to keep the oceans of the world in the pristine
condition they exist in today.
Since direct absorption of carbon
dioxide is the primary cause of ocean acidification, reducing the amount of CO2
in the atmosphere would have the greatest effect of reduction of it. A
large-scale solution is the use of CO2 scrubbers, towers that absorb
CO2 from the air. Air with CO2 enters a first tower that
contains gaseous solvents, usually ammonia, and is cooled. The ammonia absorbs
the CO2 from the air, thereby isolating it. The remaining air is now
cleaner and returned to the atmosphere. The cooled CO2 is moved to
another tower or another chamber and is heated. The CO2 and ammonia
separate and the CO2 is drawn out and pumped into storage
containers. The ammonia is recycled back to the first tower to be used again. This
process is relatively new and is still being trialed and tested, but it has
great potential. Currently, it costs $150 to remove one ton of CO2
using carbon scrubbing, which would add 4-9 cents/kilowatt to an individual’s
energy bill. In time, this cost is sure to come down as technology improves.
The towers would be placed on factories or power plants, where much of the CO2
is produced. The CO2 that has been removed from the air can be used
for useful purposes. The gas can be pumped underground into almost depleted oil
reserves. The CO2 helps dislodge the oil so that all of it can be
extracted from the ground. Carbon scrubbing can remove 80-90% of released CO2
from the atmosphere.
A second solution is the addition of
calcium carbonate to coastal waters. This solution more directly solves ocean
acidification. Calcium carbonate is the mineral that marine organisms such as
coral, crabs, and shellfish use to make their exoskeletons. Ocean acidification
inhibits their ability to use calcium carbonate to do so. By adding extra
calcium carbonate to the water, it can offset the increased CO2 and
balance marine ecosystems. The extra calcium carbonate absorbs the CO2
so that organisms can use the natural amounts for exoskeleton growth. This
solution would be most effective in coastal regions where ocean acidification
is highest and where the added calcium carbonate could be most effective. The
addition of this mineral may be a concern for environmentalists and tourists
visiting the area. They may not be too keen on adding more to the ocean.
There are a number
of causes of ocean acidification. The primary cause is the direct absorption of
Carbon Dioxide (CO2) into ocean water. CO2 emissions are
mostly manmade. Fossil fuel consumption added 5637.9 teragrams of CO2
to the atmosphere in 2006.Although steel, iron, and cement industries add hundreds of teragrams
per year, burning fossil fuels is the number one cause. When CO2 is
in the air, water can absorb it. Through chemical processes, carbonic acid is
formed which increases the acidity of the ocean. With fossil fuel usage
increasing every year, the acidification will only get worse.
Acid
rain is a secondary cause of ocean acidification. Burning fossil fuels,
farming, and raising livestock create sulfur dioxide, ammonia, and nitrogen oxide.
These gases rise into the atmosphere and then return to Earth in precipitation,
forming nitric and sulfuric acid. This is called acid rain. The rain falls on
land and in the ocean. Acid rain mainly affects coastal water areas, where
tourism is centered and people live. Acid rain that falls on land can work its
way into other bodies of water, such as rivers and streams, and flow into the
ocean.
Deforestation
is another secondary cause of ocean acidification that is linked to CO2
production. Trees and other plants use CO2 in photosynthesis to live
and produce oxygen.The removal of
CO2 by agriculture and forestry is called carbon sequestration.
Deforestation decreases the amount of trees that can remove CO2,
thereby increasing CO2 content. A single acre of trees can remove 4
tons of CO2 from the atmosphere per year. This may not seem like a
lot, but a large, undisturbed forest with thousands of acres can have a
noticeable effect.
-Occurs when the oxygen concentration in the
water falls below 2mg/L, the necessary level to sustain most animal life
Eutrophication
-The addition of excessive amounts of nitrates
and phosphates, which when added to a marine environment causes accelerated
stimulated plant and algae growth and depletes the normal amount of oxygen
necessary for marine life
-Creates algae blooms which can be deadly to the
surrounding plant and animal life
-Largest eutrophic zones are located around
industrialized areas with tons of water pollution each year
Causes of Eutrophication
-Point Sources
oAny single identifiable source of pollution from
which pollutants are released such as a sewage pipe from an industrial factory
-Nonpoint Sources
oGenerally caused by runoff from rain and seepage
oFertilizers in a high water table zone
Problems Caused
-decrease in the population of species in hypoxic
areas
-destruction of coral reef ecosystems
-leads to dead zones where no life can be sustained
-damages the economic coastal fishing industry
-lowers the reproductive hormones in male and
female fish in hypoxic environments
Ways to Solve
-addition of aluminum sulfate in the water to
decrease levels of phosphates
-decreasing the amount of point and nonpoint
sources of pollution in coastal industrial areas
