- ID
- 545344
- Banca
- CESGRANRIO
- Órgão
- PETROQUÍMICA SUAPE
- Ano
- 2011
- Provas
- Disciplina
- Inglês
- Assuntos
Cleaning up a spill
Written by Laura Hill
Water and oil don’t mix. We see this every day;
just try washing olive oil off your hands without soap
or washing your face in the morning with only water. It
just doesn’t work!
When an oil spill occurs in the ocean, like the
catastrophe in the Gulf of Mexico, what do scientists
do to clean up the toxic mess? There are a number of
options for an oil spill cleanup and most efforts use a
combination of many techniques. The fact that oil and
water don’t mix is a blessing and a curse. If oil mixed
with water, it would be difficult to divide the two.
Crude oil is less dense than water; it spreads out
to make a very thin layer (about one millimetre thick)
that floats on top of the water. This is good because
we can tell what is water and what is oil. It is also bad,
because it means the oil can spread really quickly
and cover a very large area, which becomes difficult
to manage. Combined with wind, ocean currents and
waves, oil spill cleanup starts to get really tricky.
Chemical dispersants can be used to break
up big oil slicks into small oil droplets. They work
like soaps by emulsifying the hydrophobic (waterrepelling)
oil in the water. These small droplets can
degrade in the ecosystem quicker than the big oil
slick. But unfortunately, this means that marine life
of all sizes ingest these toxic, broken-down particles
and chemicals.
If the oil is thick enough, it could be set fire, a
process called “in situ burning”. Because the oil is
highly flammable and floats on top of the water, it
is very easy to set it alight. It’s not environmentallyfriendly
though; the combustion of oil releases thick
smoke that contains greenhouse gases and other
dangerous air pollutants.
Some techniques can contain and recapture
spilled oil without changing its chemical composition.
Booms float on top of the water and act as barriers to
the movement of oil. Once the oil is controlled, it can
be gathered using sorbents. “Sorbent” is a fancy word
for sponge. These sponges absorb the oil and allow it
to be collected by siphoning it off the water.
However, weather and sea conditions can prevent
and obstruct the use of booms, sorbents and in situ
burning. Imagine trying to perform these operations
on the open sea with wind, waves and water currents
moving the oil (and your boat!) around on the water.
What about the plants and animals? It’s easy to
forget about the organisms in the sea that are under
water. Out of sight, out of mind! There is not much we
can do to help them. But when oil reaches the shore it
impacts sensitive coastal environments including the
many fish, bird, amphibian, reptilian, and crustaceanspecies that live there. We have easy access to these
areas and there are some things we can do to clean
up. For the plants, it is often a matter of setting them
on fire, or leaving them to degrade the oil naturally.
Sometimes, we can spray the oil with nutrients
(phosphorus and nitrogen) that can encourage the
growth of specialized microorganisms. For species
that can tolerate our soaps, manpower is needed to
wash every affected animal. Yet, if the animal has
tried to lick itself clean, it can die from ingesting the
toxic oil.
Unfortunately, there can be many negative
economic and social impacts, in addition to the
environmental impacts of oil spills and, as you’ve just
read, the clean up techniques are far from perfect.
Prevention is the very best cleanup technique we
have.
http://www.curiocity.ca/everyday-science/environme...
-cleaning-up-a-spill.html, retrieved on Dec 10, 2010