Environmental Engineering Reference
In-Depth Information
position of organic matter present in the reservoirs (especially if vegetation is not
removed before flooding); however, construction and decommissioning of hydro-
electricity plants results in CO
2
emissions.
An oil spill is a release of a liquid petroleum hydrocarbon into the environment
due to human activity. The term often refers to marine oil spills, where oil is re-
leased into the ocean or coastal waters. Oil spills include releases of crude oil from
tankers, offshore platforms, drilling rigs and wells, as well as spills of refined pet-
roleum products (such as gasoline, diesel) and their by-products, heavier fuels used
by large ships such as bunker fuel, or the spill of any oily refuse or waste oil. About
half of the 30 billion barrels of oil consumed annually are transported by sea, where
spills occur frequently. Oil pollution is a highly visible form of marine pollution
and, therefore, has resulted in great public outcry and in resulting corrective meas-
ures. Average annual spillage from natural seeps and transportation is 9 million
barrels, of which 1.8 million barrels are leaked in US waters.
The recent accident in deepwater exploration in the Gulf of Mexico highlighted
the seriousness of the problem of oil spills. The Macondo well, was being drilled
off the Louisiana coast by BP (British Petroleum) PLC using Transocean Ltd.'s
Deepwater Horizon semisubmersible floating drilling rig. High pressure methane
gas escaped, ignited and exploded engulfing the drilling rig and sank it, starting
an oil spill of disastrous proportions. The spill amounted to 2.3 million barrels, ac-
cording to BP estimates.
It was not the first of its kind in the Gulf of Mexico, and its environmental
consequences were not more serious because much of the marine life in the area
had been depleted over the centuries by pollution originating from the Mississippi
River. The Ixtoc wildcat well blew out in mid-1979 while being drilled by Petro-
leos Mexicanos, resulting in what is now known as the second-largest spill in his-
tory. The Ixtoc blowout discharged an estimated 3.3 million barrels of oil into the
Gulf until it was capped, nearly 10 months later, on March 23, 1980.
Table 8.2
lists
major oil spill disasters.
Table 8.2 Major oil spill disasters
