Environmental Engineering Reference
In-Depth Information
chemicals which resist photo-chemical, biological and chemical degradation.
Many of the leachants are toxic to lora and fauna.
The North Paciic gyre, also known as the Great Paciic Garbage Patch, is twice the
size of Texas and swirls in the Paciic Ocean between the coast of California and
Hawaii, USA. An estimated 11 million tonnes of loating plastic covers an area of
nearly 13 million square kilometers in the Paciic Ocean. Plastic trash that is either
directly thrown away or washed by heavy rains and rivers into the North Paciic
Ocean, is swept up in the swirling vortex into this gyre. Very few living organisms
are seen on the sea loor beneath the South Paciic gyre, levels which are about three
or four times lower than those outside the gyre. Approximately 80% of this plastic
pollution originates from the land, and the rest is produced from recreational boats,
commercial operations, maritime industries, and the military.
Many hazardous chemicals including gasoline, motor oil, anti-freeze from cars,
pesticides and fertilisers from agricultural operations, manure from stockyards
and animal processing plants, and human waste from septic systems and sewage
treatment plants are also found as waste in the sea. Compounds found in this waste
can include: dichlorodiphenyl trichloroethane (DDT) and DDE pesticides, PCB (found
in automobile luids and lame retardants), and dioxins (found in herbicides and as
a by-product of waste incinerators) and many others, which are termed POP. Many
of these pollutants are carcinogens, and are harmful to animals and humans when
ingested. Studies have shown that these ocean-borne plastic particles contain POP
levels up to a million times higher than levels in the surrounding sea water, probably
because they absorb the POP. So gyres are also called toxic soup.
Plastic is hydrophobic petroleum-based product, which attracts other similar chemicals
to its surface, thereby becoming a vehicle to transport toxins.
Small marine creatures consume these small fragments, mistaking them for
phytoplankton and then die because of bio-accumulation. Toxic compounds build
up in an organism at a faster rate than they are broken down, which has impacts on
the food chain. Ultimately, these harmful substances end up in the food of humans.
Sea animals such as sea turtles and birds also consume larger bits of plastic mistaking
them for food. These cannot pass through the digestive systems choking them. Also as
they have no nutritional value, the animal slowly starves to death. When the animal
dies and its body decomposes, the plastic is released back into the environment and
it will continue to cause harm to the environment.
