oil spill
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An oil spill is the release of a liquid
petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic, and their odors are usuall ...
into the environment, especially the
marine ecosystem Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in Saline water, waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70 ...
, due to human activity, and is a form of
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
. The term is usually given to marine oil spills, where oil is released into the ocean or
coastal waters The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
, but spills may also occur on land. Oil spills may be due to releases of
crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
from tankers, offshore platforms,
drilling rig A drilling rig is an integrated system that drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill wate ...
s and wells, as well as spills of refined petroleum products (such as
gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most Spark-ignition engine, spark-ignited internal combustion engines (also known as petrol engines). It consists ...
, diesel) and their by-products, heavier fuels used by large ships such as
bunker fuel Fuel oil is any of various fractional distillation, fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residue (chemistry), residues (the heavier fractions). Fuel oils inclu ...
, or the spill of any oily refuse or
waste oil Waste oil is defined as any petroleum-based or synthetic oil that, through contamination, has become unsuitable for its original purpose due to the presence of impurities or loss of original properties. Differentiating between "waste oil" and "use ...
. Oil spills penetrate into the structure of the
plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
of birds and the
fur
fur
of mammals, reducing its insulating ability, and making them more vulnerable to temperature fluctuations and much less
buoyant Buoyancy (), or upthrust, is an upward force In physics, a force is an influence that can change the motion of an Physical object, object. A force can cause an object with mass to change its velocity (e.g. moving from a Newton's first ...

buoyant
in the water. Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), and the types of shorelines and beaches involved. Spills may take weeks, months or even years to clean up. Oil spills can have disastrous consequences for society; economically, environmentally, and socially. As a result, oil spill accidents have initiated intense media attention and political uproar, bringing many together in a political struggle concerning government response to oil spills and what actions can best prevent them from happening.


Largest oil spills

Crude oil and refined fuel spills from tanker ship accidents have damaged vulnerable
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

ecosystem
s in
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Central Alaskan Yup'ik language, Yup'ik: ''Alaskaq''; tli, Anáaski) is a U.S. state, state located in the Western United States on the northwest extremity o ...

Alaska
, the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

Gulf of Mexico
, the Galapagos Islands,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

France
, the
Sundarbans Sundarbans (pronounced ) is a mangrove area in Ganges Delta, the delta formed by the confluence of the Padma River, Padma, Brahmaputra River, Brahmaputra and Meghna Rivers in the Bay of Bengal. It spans the area from the Baleswar River in Bang ...

Sundarbans
,
Ogoniland The Ogonis are a people in the Rivers South East senatorial district of Rivers State, in the Niger Delta region of southern Nigeria. They number just over 2 million and live in a homeland which they also refer to as Ogoniland. They share common o ...
, and many other places. The quantity of oil spilled during accidents has ranged from a few hundred tons to several hundred thousand tons (e.g., ''Deepwater Horizon'' Oil Spill, ''
Atlantic Empress SS ''Atlantic Empress'' was a Greek oil tanker that in 1979 collided with the oil tanker ''Aegean Captain'' in the Caribbean, and eventually sank, having created the fifth Oil spill#Largest oil spills, largest oil spill on record and the larges ...
'', ''
Amoco Cadiz ''Amoco Cadiz'' was a VLCC (very large crude carrier) owned by Amoco, Amoco Transport Corp and transporting crude oil for Royal Dutch Shell, Shell Oil. Operating under the Liberian flag of convenience, she ran aground on 16 March 1978 on Portsal ...
''), but volume is a limited measure of damage or impact. Smaller spills have already proven to have a great impact on ecosystems, such as the
''Exxon Valdez'' oil spill
''Exxon Valdez'' oil spill
because of the remoteness of the site or the difficulty of an emergency environmental response. Oil spills in the Niger Delta are among the worst on the planet. Between 1970 and 2000, there were over 7,000 spills. Between 1956 and 2006, up to 1.5 million tons of oil were spilled in the
Niger Delta The Niger Delta is the River delta, delta of the Niger River sitting directly on the Gulf of Guinea on the Atlantic Ocean in Nigeria. It is located within nine coastal southern Nigerian states, which include: all six states from the South South ...
. Oil spills at sea are generally much more damaging than those on land, since they can spread for hundreds of nautical miles in a thin oil slick which can cover beaches with a thin coating of oil. These can kill seabirds, mammals, shellfish and other organisms they coat. Oil spills on land are more readily containable if a makeshift earth dam can be rapidly
bulldozed A bulldozer or dozer (also called a crawler) is a large, motorized machine A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, movement to perform an action. The term is commonly applied ...
around the spill site before most of the oil escapes, and land animals can avoid the oil more easily.


Human impact

An oil spill represents an immediate negative effects on human health, including respiratory and reproductive problems as well as liver, and immune system damage. Oil spills causing future oil supply to decline also effects the everyday life of humans such as the potential closure of beaches, parks, fisheries and fire hazards. The
Kuwaiti oil fires The Kuwaiti oil fires were caused by the Iraqi Armed Forces, Iraqi military setting fire to a reported 605 to 732 oil wells along with an unspecified number of oil filled low-lying areas, such as oil lakes and fire trenches, as part of a scorched ...
produced
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...

air pollution
that caused respiratory distress. The ''Deepwater Horizon'' explosion killed eleven oil rig workers. The fire resulting from the Lac-Mégantic derailment killed 47 and destroyed half of the town's centre. Spilled oil can also contaminate drinking water supplies. For example, in 2013 two different oil spills contaminated water supplies for 300,000 in
Miri ) , subdivision_type = Country , subdivision_name = , subdivision_type1 = States and federal territories of Malaysia, State , subdivision_name1 = , subdivision_type2 ...
,
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Malaysia
; 80,000 people in Coca, Ecuador. In 2000, springs were contaminated by an oil spill in Clark County, Kentucky. Contamination can have an economic impact on tourism and marine resource extraction industries. For example, the ''Deepwater Horizon'' oil spill impacted beach tourism and fishing along the Gulf Coast, and the responsible parties were required to compensate economic victims.


Environmental effects

The threat posed to birds, fish, shellfish and crustaceans from spilled oil was known in England in the 1920s, largely through observations made in
Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...

Yorkshire
. The subject was also explored in a scientific paper produced by the
National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...
in the US in 1974 which considered impacts to fish, crustaceans and molluscs. The paper was limited to 100 copies and was described as a draft document, not to be cited. In general, spilled oil can affect animals and plants in two ways: dirесt from the oil and from the response or cleanup process. There is no clear relationship between the amount of oil in the aquatic environment and the likely impact on biodiversity. A smaller spill at the wrong time/wrong season and in a sensitive environment may prove much more harmful than a larger spill at another time of the year in another or even the same environment. Oil penetrates into the structure of the plumage of birds and the fur of mammals, reducing their insulating ability, and making them more vulnerable to temperature fluctuations and much less buoyant in the water. Animals who rely on scent to find their babies or mothers cannot do so due to the strong scent of the oil. This causes a baby to be rejected and abandoned, leaving the babies to starve and eventually die. Oil can impair a bird's ability to fly, preventing it from foraging or escaping from predators. As they preen, birds may ingest the oil coating their feathers, irritating the
digestive tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organ Organ may refer to: Biology * Org ...
, altering
liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

liver
function, and causing
kidney The kidneys are two reddish-brown bean-shaped organ (anatomy), organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal ...

kidney
damage. Together with their diminished foraging capacity, this can rapidly result in
dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of Metabolism, metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental tempe ...

dehydration
and
metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

metabolic
imbalance. Some birds exposed to petroleum also experience changes in their hormonal balance, including changes in their luteinizing protein. The majority of birds affected by oil spills die from complications without human intervention. Some studies have suggested that less than one percent of oil-soaked birds survive, even after cleaning, although the survival rate can also exceed ninety percent, as in the case of the ''MV Treasure'' oil spill. Oil spills and oil dumping events have been impacting sea birds since at least the 1920s and was understood to be a global problem in the 1930s. Heavily furred exposed to oil spills are affected in similar ways. Oil coats the fur of
sea otters The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern Pacific Ocean, North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the Mustelidae, weasel f ...

sea otters
and seals, reducing its insulating effect, and leading to fluctuations in
body temperature Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
and
hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
. Oil can also blind an animal, leaving it defenseless. The ingestion of oil causes dehydration and impairs the digestive process. Animals can be poisoned, and may die from oil entering the lungs or liver. In addition, oil spills can also harm air quality. The chemicals in crude oil are mostly hydrocarbons that contains toxic chemicals such as
benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar Ring (chemistry), ring with one hydrogen atom ...

benzene
s,
toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water (molecule), water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a met ...

toluene
, poly-aromatic hydrocarbon and oxygenated
polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. P ...
s. These chemicals can introduce adverse health effects when being inhaled into human body. In addition, these chemicals can be oxidized by oxidants in the atmosphere to form fine particulate matter after they evaporate into the atmosphere. These particulates can penetrate lungs and carry toxic chemicals into the human body. Burning surface oil can also be a source for pollution such as soot particles. During the cleanup and recovery process, it will also generate air pollutants such as nitric oxides and ozone from ships. Lastly, bubble bursting can also be a generation pathway for particulate matter during an oil spill. During the
Deepwater Horizon oil spill The ''Deepwater Horizon'' oil spill (also referred to as the "BP oil spill") was an industrial disaster that began on 20 April 2010 off of the coast of the United States in the Gulf of Mexico on the BP-operated Macondo Prospect, considered ...
, significant air quality issues were found on the Gulf Coast, which is the downwind of DWH oil spill. Air quality monitoring data showed that criteria pollutants had exceeded the health-based standard in the coastal regions.


Sources and rate of occurrence

Oil spills can be caused by human error, natural disasters, technical failures or deliberate releases. It is estimated that 30-50% of all oil spills are directly or indirectly caused by human error, with approximately 20-40% of oil spills being attributed to equipment failure or malfunction. Causes of oil spills are further distinguished between deliberate releases, such as operational discharges or acts of war and accidental releases. Accidental oil spills are in the focus of the literature, although some of the largest oil spills ever recorded, the
Gulf War Oil Spill The Gulf War oil spill, or the Persian Gulf oil spill, was one of the Oil spills#Largest oil spills, largest oil spills in history, resulting from the Gulf War in 1991. In January 1991, Iraqi forces allegedly began dumping oil into the Persian Gulf ...
(sea based) and
Kuwaiti Oil Fires The Kuwaiti oil fires were caused by the Iraqi Armed Forces, Iraqi military setting fire to a reported 605 to 732 oil wells along with an unspecified number of oil filled low-lying areas, such as oil lakes and fire trenches, as part of a scorched ...
(land based) were deliberate acts of war. The academic study of sources and causes of oil spills identifies vulnerable points in oil transportation infrastructure and calculates the likelihood of oil spills happening. This can then guide prevention efforts and regulation policies


Natural seeps

Around 40-50% of all oil released into the oceans stems from natural seeps from seafloor rocks. This corresponds to approximately 600,000 tons annually on a global level. While natural seeps are the single largest source of oil spills, they are considered less problematic because ecosystems have adapted to such regular releases. For instance, on sites of natural oil seeps, ocean bacteria have evolved to digest oil molecules.


Oil tankers and vessels

Vessels can be the source of oil spills either through operational releases of oil or in the case of
oil tanker An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...
accidents. Operational discharges from vessels are estimated to account for 21% of oil releases from vessels. They occur as a consequence of failure to comply with regulations or arbitrary discharges of waste oil and water containing such oil residues. Such operational discharges are regulated through the MARPOL convention. Operational releases are frequent, but small in the amount of oil spilled per release, and are often not in the focus of attention regarding oil spills. There has been a steady decrease of operational discharges of oil, with an additional decrease of around 50% since the 1990s. Accidental oil tank vessel spills account for approximately 8-13% of all oil spilled into the oceans. The main causes of oil tank vessel spills are collision (29%), grounding (22%), mishandling (14%) and sinking (12%), among others. Oil tanker spills are considered a major ecological threat due to the large amount of oil spilled per accident and the fact that major sea traffic routes are close to Large Marine Ecosystems. Around 90% of the world's oil transportation is through oil tankers, and the absolute amount of seaborne oil trade is steadily increasing. However, there has been a reduction of the number of spills from oil tankers and of the amount of oil released per oil tanker spill. In 1992,
MARPOL The International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978, or "MARPOL 73/78" is one of the most important international marine international environmental law, environmental conventions. ...
was amended and made it mandatory for large tankers (5,000 dwt and more) to be fitted with
double hull A double hull is a ship Hull (watercraft), hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull ...
s. This is considered to be a major reason for the reduction of oil tanker spills, alongside other innovations such as
GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
, sectioning of vessels and
sea lane A sea lane, sea road or shipping lane is a regularly used navigable route for large water vessels (ships) on wide waterways such as oceans and large lakes, and is preferably safe, direct and economic. During the Age of Sail, they were determined b ...
s in narrow straits.


Offshore oil platforms

Accidental spills from
oil platform An oil platform (or oil rig, offshore platform, oil production platform, and similar terms) is a large structure with facilities to extract and process petroleum and natural gas that lie in rock formations beneath the seabed. Many oil platfor ...
s nowadays account for approximately 3% of oil spills in the oceans. Prominent offshore oil platform spills typically occurred as a result of a blowout. They can go on for months until relief wells have been drilled, resulting in enormous amounts of oil leaked. Notable examples of such oil spills are Deepwater Horizon and Ixtoc I. While technologies for drilling in deep water have significantly improved in the past 30–40 years, oil companies move to drilling sites in more and more difficult places. This ambiguous development results in no clear trend regarding the frequency of offshore oil platform spills.


Pipelines

Pipelines as sources of oil spills are estimated to contribute 1% of oil pollution to the oceans. Reasons for this are underreporting, and many oil pipeline leaks occur on land with only fractions of that oil reaching the oceans. Overall, however, there has been a substantial increase of pipeline oil spills in the past four decades. Prominent examples include oil spills of pipelines in the Niger Delta. Pipeline oil spills can be caused by trawling of fishing boats, natural disasters, pipe corrosion, construction defects and deliberate sabotage or attacks, as with the Caño Limón-Coveñas pipeline in Colombia.


Other sources

Recreational boats can spill oil into the ocean because of operational or human error and unpreparedness. The amounts are however small, and such oil spills are hard to track due to underreporting. Oil can reach the oceans as oil and fuel from land-based sources. It is estimated that runoff oil and oil from rivers are responsible for 11% of oil pollution to the oceans. Such pollution can also be oil on roads from land vehicles, which is then flushed into the oceans during rainstorms. Purely land-based oil spills are different from maritime oil spills in that oil on land does not spread as quickly as in water, and effects thus remain local.


Cleanup and recovery

Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), and the types of shorelines and beaches involved. Physical cleanups of oil spills are also very expensive. Until the 1960s, the best method for remediation consisted of putting
straw Straw is an agricultural byproduct consisting of the dry wikt:stalk, stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has ...
on the spill and retrieving the oil-soaked straw manually. Chemical remediation is the norm as of the early 21st Century, using compounds that can herd and thicken oil for physical recover, disperse oil in the water, or facilitate burning the oil off. The future of oil cleanup technology is likely the use of microorganisms such as Fusobacteriota (formerly Fusobacteria), species demonstrate potential for future oil spill cleanup because of their ability to colonize and degrade oil slicks on the sea surface. There are three kinds of oil-consuming bacteria. Sulfate-reducing bacteria (SRB) and acid-producing bacteria are
anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...
, while general aerobic bacteria (GAB) are
aerobic Aerobic means "requiring Earth's atmosphere, air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Cellular respiration#Aerobic ...
. These bacteria occur naturally and will act to remove oil from an ecosystem, and their biomass will tend to replace other populations in the food chain. The chemicals from the oil which dissolve in water, and hence are available to bacteria, are those in the water associated fraction of the oil. Methods for cleaning up include: *
Bioremediation Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi, and plants), living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluent ...
: use of
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s or biological agents to break down or remove oil; such as '' Alcanivorax'' bacteria or '' Methylocella silvestris''. * Bioremediation Accelerator: a binder molecule that moves hydrocarbons out of water and into gels, when combined with nutrients, encourages natural bioremediation. Oleophilic, hydrophobic chemical, containing no bacteria, which chemically and physically bonds to both soluble and insoluble hydrocarbons. The accelerator acts as a herding agent in water and on the surface, floating molecules such as phenol and BTEX to the surface of the water, forming gel-like agglomerations. Undetectable levels of hydrocarbons can be obtained in produced water and manageable water columns. By overspraying sheen with bioremediation accelerator, sheen is eliminated within minutes. Whether applied on land or on water, the nutrient-rich emulsion creates a bloom of local, indigenous, pre-existing, hydrocarbon-consuming bacteria. Those specific bacteria break down the hydrocarbons into water and carbon dioxide, with EPA tests showing 98% of alkanes biodegraded in 28 days; and aromatics being biodegraded 200 times faster than in nature they also sometimes use the hydrofireboom to clean the oil up by taking it away from most of the oil and burning it. * Controlled
burning Combustion, or burning, is a high-temperature exothermic redox chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances ...
can effectively reduce the amount of oil in water, if done properly. But it can only be done in low
wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating ...
, and can cause
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...

air pollution
. *
Dispersant A dispersant or a dispersing agent is a substance, typically a surfactant, that is added to a suspension (chemistry), suspension of solid or liquid particles in a liquid (such as a colloid or emulsion) to improve the separation of the particles an ...
s can be used to dissipate oil slicks. A dispersant is either a non-surface active
polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules called macromolecules, composed of many Repeat unit, repeating subunits. Due to t ...
or a surface-active substance added to a suspension, usually a
colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others ext ...
, to improve the separation of particles and to prevent
settling Settling is the process by which particulates move towards the bottom of a liquid and form a sediment. Particles that experience a force, either due to gravity or due to Centrifuge, centrifugal motion will tend to move in a uniform manner in the ...
or clumping. They may rapidly disperse large amounts of certain oil types from the
sea surface The sea, connected as the world ocean or simply the ocean, is the body of water, body of saline water, salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote List of seas, second-order sections of ...
by transferring it into the
water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
. They will cause the oil slick to break up and form water-soluble
micelle A micelle () or micella () (plural micelles or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloid, colloidal suspension (also known as associat ...
s that are rapidly diluted. The oil is then effectively spread throughout a larger volume of water than the surface from where the oil was dispersed. They can also delay the formation of persistent
oil-in-water emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...
s. However, laboratory experiments showed that dispersants increased toxic hydrocarbon levels in fish by a factor of up to 100 and may kill fish eggs. Dispersed oil droplets infiltrate into deeper water and can lethally contaminate
coral Corals are marine invertebrates within the class (biology), class Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important C ...
. Research indicates that some dispersants are toxic to corals. A 2012 study found that Corexit dispersant had increased the toxicity of oil by up to 52 times. In 2019, the U.S. National Academies released a report analyzing the advantages and disadvantages of several response methods and tools. * Watch and wait: in some cases, natural attenuation of oil may be most appropriate, due to the invasive nature of facilitated methods of remediation, particularly in ecologically sensitive areas such as wetlands. *
Dredging Dredging is the Digging, excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constru ...
: for oils dispersed with detergents and other oils denser than water. * Skimming: Requires calm waters at all times during the process. Vessels used for skimming clean up are called Gulp Oil Skimmers. * Solidifying: Solidifiers are composed of tiny, floating,
dry ice Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and Sublimation (phase transition), sublimates directly from the solid state to the ga ...
pellets, and
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly intermolecular force, repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend t ...
polymers A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules called macromolecules, composed of many Repeat unit, repeating subunits. Due to t ...
that both
adsorb Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a Surface science, surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorpti ...
and absorb. They clean up oil spills by changing the physical state of spilled oil from liquid to a solid, semi-solid or a rubber-like material that floats on water. Solidifiers are
insoluble In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, st ...
in water, therefore the removal of the solidified oil is easy and the oil will not leach out. Solidifiers have been proven to be relatively non-toxic to aquatic and wildlife and have been proven to suppress harmful vapors commonly associated with hydrocarbons such as
benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar Ring (chemistry), ring with one hydrogen atom ...

benzene
,
xylene In organic chemistry, xylene or xylol (; IUPAC name: dimethylbenzene) are any of three organic compounds with the formula . They are derived from the substitution of two hydrogen atoms with methyl groups in a benzene ring; which hydrogens are sub ...
and
naphtha Naphtha ( or ) is a flammable liquid hydrocarbon mixture. Mixtures labelled ''naphtha'' have been produced from natural gas condensates, petroleum distillates, and the distillation of coal tar and peat. In different industries and regions ''n ...
. The reaction time for solidification of oil is controlled by the surface area or size of the polymer or dry pellets as well as the viscosity and thickness of the oil layer. Some solidifier product manufacturers claim the solidified oil can be thawed and used if frozen with dry ice or disposed of in landfills, recycled as an additive in asphalt or rubber products, or burned as a low ash fuel. A solidifier called C.I.Agent (manufactured by C.I.Agent Solutions of
Louisville, Kentucky Louisville ( , , ) is the List of cities in Kentucky, largest city in the Kentucky, Commonwealth of Kentucky and the list of United States cities by population, 28th most-populous city in the United States. Louisville is the historical coun ...
) is being used by BP in granular form, as well as in Marine and Sheen Booms at Dauphin Island and Fort Morgan, Alabama, to aid in the
Deepwater Horizon oil spill The ''Deepwater Horizon'' oil spill (also referred to as the "BP oil spill") was an industrial disaster that began on 20 April 2010 off of the coast of the United States in the Gulf of Mexico on the BP-operated Macondo Prospect, considered ...
cleanup. * Vacuum and
centrifuge A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by rotation around a fixed axis, spinning the fluid at high speed within a container, thereby separating fluids of different densiti ...
: oil can be sucked up along with the water, and then a centrifuge can be used to separate the oil from the water – allowing a tanker to be filled with near pure oil. Usually, the water is returned to the sea, making the process more efficient, but allowing small amounts of oil to go back as well. This issue has hampered the use of centrifuges due to a United States regulation limiting the amount of oil in water returned to the sea. * Beach Raking: coagulated oil that is left on the beach can be picked up by machinery. Equipment used includes: * Booms: large floating barriers that round up oil and lift the oil off the water * Skimmers: skim the oil * Sorbents: large absorbents that absorb oil and adsorb small droplets * Chemical and biological agents: helps to break down the oil * Vacuums: remove oil from beaches and water surface *
Shovel A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Most shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are usually made of ...
s and other road equipment: typically used to clean up oil on beaches


Prevention

* Secondary containment – methods to prevent releases of oil or hydrocarbons into the environment. * Oil Spill Prevention Control and Countermeasures (SPCC) program by the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
. * Double-hulling – build
double hull A double hull is a ship Hull (watercraft), hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull ...
s into vessels, which reduces the risk and severity of a spill in case of a collision or grounding. Existing single-hull vessels can also be rebuilt to have a double hull. * Thick-hulled railroad transport tanks. Spill response procedures should include elements such as; * A listing of appropriate protective clothing, safety equipment, and cleanup materials required for spill cleanup (gloves, respirators, etc.) and an explanation of their proper use; * Appropriate evacuation zones and procedures; * Availability of fire suppression equipment; * Disposal containers for spill cleanup materials; and * The first aid procedures that might be required.


Environmental Sensitivity Index (ESI) mapping

Environmental Sensitivity Indexes (ESI) are tools used to create Environmental Sensitivity Maps (ESM). ESM's are pre-planning tools used to identify sensitive areas and resources prior to an oil spill event in order to set priorities for protection and plan clean-up strategies. It is to date the most commonly used mapping tool for sensitive area plotting. The ESI has three components: A shoreline type ranking system, a biological resources section, and a human-use resource category.NOAA (2002). Environmental Sensitivity Index Guidelines, version 3.0. NOAA Technical Memorandum NOS OR&R 11. Seattle: Hazardous Response and Assessment Division, National Oceanic and Atmospheric Administration, 129p.


History and development

ESI is the most frequently used sensitivity mapping tool yet. It was first applied in 1979 in response to an oil-spill near Texas in the Gulf of Mexico. To this time, ESI maps were prepared merely days in advance of one's arrival to an oil spill location. ESMs used to be atlases, maps consisting of thousands of pages that could solely work with spills in the oceans. In the past 3 decades, this product has been transformed into a versatile online tool. This conversion allows sensitivity indexing to become more adaptable and in 1995 by the US National Oceanic and Atmospheric Administration (NOAA) worked on the tool allowing ESI to extended maps to lakes, rivers, and estuary shoreline types. ESI maps have since become integral to  collecting, synthesizing, and producing data which have previously never been accessible in digital formats. Especially in the United States, the tool has made impressive advancements in developing tidal bay protection strategies, collecting seasonal information and generally in the modelling of sensitive areas. Together with Geographic Information System Mapping (GIS), ESI integrates their techniques to successfully geographically reference the three different types of resources.


Usage and application

The ESI depicts environmental stability, coastal resilience to maritime related catastrophes, and the configurations of a stress-response relationship between all things maritime. Created for ecological-related decision making, ESMs can accurately identify sensitive areas and habitats, clean-up responses, response measures and monitoring strategies for oil-spills. The maps allow experts from varying fields to come together and work efficiently during fast-paced response operations. The process of making an ESI atlas involves GIS technology. The steps involve, first zoning the area that is to be mapped, and secondly, a meeting with local and regional experts on the area and its resources.IPIECA, IMO, OGP. (2012). ''Sensitivity mapping for oil spill response'' (OGP Report Number 477). Following, all the shoreline types, biological, and human use resources need to be identified and their locations pinpointed. Once all this information is gathered, it then becomes digitized. In its digital format, classifications are set in place, tables are produced and local experts refine the product before it gets released. ESI's current most common use is within contingency planning. After the maps are calculated and produced, the most sensitive areas get picked out and authenticated. These areas then go through a scrutinization process throughout which methods of protection and resource assessments are obtained. This in-depth research is then put back into the ESMs to develop their accuracy and allowing for tactical information to be stored in them as well. The finished maps are then used for drills and trainings for clean-up efficiency. Trainings also often help to update the maps and tweak certain flaws that might have occurred in the previous steps.


ESI Categories


Shoreline type

Shoreline A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past a ...
type is classified by rank depending on how easy the target site would be to clean up, how long the oil would persist, and how sensitive the shoreline is. The ranking system works on a 10-point scale where the higher the rank, the more sensitive a habitat or shore is. The coding system usually works in colour, where warm colours are used for the increasingly sensitive types and cooler colours are used for robust shores. For each navigable body of water, there is a feature classifying its sensitivity to oil. Shoreline type mapping codes a large range of ecological settings including
estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...
,
lacustrine A lake is an area filled with water, localized in a Depression (geology), basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the World Ocean, oce ...
, and
riverine A river is a natural flowing watercourse A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on ...
environments. Floating oil slicks put the shoreline at particular risk when they eventually come ashore, covering the substrate with oil. The differing substrates between shoreline types vary in their response to oiling, and influence the type of cleanup that will be required to effectively decontaminate the shoreline. Hence ESI shoreline ranking helps committees identify which clean-up techniques are approved or detrimental the natural environment. The exposure the shoreline has to wave energy and tides, substrate type, and slope of the shoreline are also taken into account—in addition to biological productivity and sensitivity.NOAA (2008). Introduction to Environmental Sensitivity Index maps. NOAA Technical Manual. Seattle: Hazardous Response and Assessment Division, National Oceanic and Atmospheric Administration, 56p.
Mangroves A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...
and marshes tend to have higher ESI rankings due to the potentially long-lasting and damaging effects of both oil contamination and cleanup actions. Impermeable and exposed surfaces with high wave action are ranked lower due to the reflecting waves keeping oil from coming onshore, and the speed at which natural processes will remove the oil.


Biological resources

Within the biological resources, the ESI maps protected areas as well as those with bio-diverse importance. These are usually identified through the UNEP-WCMC Integrated Biodiversity Assessment Tool. There are varying types of coastal habitats and ecosystems and thus also many endangered species that need to be considered when looking at affected areas post oil spills. The habitats of plants and animals that may be at risk from oil spills are referred to as "elements" and are divided by functional group. Further classification divides each element into species groups with similar life histories and behaviors relative to their vulnerability to oil spills. There are eight element groups: birds, reptiles, amphibians, fish, invertebrates, habitats and plants, wetlands, and marine mammals and terrestrial mammals. Element groups are further divided into sub-groups, for example, the ‘marine mammals’ element group is divided into
dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the br ...
s, manatees,
pinnipeds Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammal, marine mammals. They comprise the extant taxon, extant family (biology ...
(seals, sea lions & walruses),
polar bear The polar bear (''Ursus maritimus'') is a Hypercarnivore, hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest ext ...
s,
sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern Pacific Ocean, North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the Mustelidae, weasel f ...
s and
whale Whales are a widely distributed and diverse group of fully Aquatic ecosystem, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Ce ...
s. Necessary when ranking and selecting species is their vulnerability to the oil spills themselves. This not only includes their reactions to such events but also their fragility, the scale of large clusters of animals, whether special life stages occur ashore, and whether any present species is threatened, endangered or rare. IMO/ IPIECA (1994). Sensitivity Mapping for Oil Spill Response. International Maritime Organization/ International Petroleum Industry Environmental Conservation Association Report Series, Volume 1. 22p. The way in which the biological resources are mapped is through symbols representing the species, and polygons and lines to map out the special extent of the species.IPIECA, IMO (1994). ''Sensitivity Mapping for Oil Spill Response'', (IMO/IPIECA report series). Volume 1, p.28 The symbols also have the ability to identify the most vulnerable of a species life stages, such as the
molting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
, nesting, hatching or migration patterns. This allows for more accurate response plans during those given periods. There is also a division for sub-tidal habitats which are equally important to coastal biodiversity including kelp, coral reefs and sea beds which are not commonly mapped within the shoreline ESI type.


Human-use resources

Human-use resources are also often referred to as socio-economic features, which map inanimate resources that have the potential to be directly impacted by oil pollution. Human-use resources that are mapped within the ESI will have socio-economic repercussions to an oil spill. These resources are divided into four major classifications:
archaeological Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscapes ...
importance or cultural resource site, high-use recreational areas or shoreline access points, important protected management areas, and resource origins. Some examples include airports, diving sites, popular beach sites, marinas, hotels, factories, natural reserves or marine sanctuaries. When mapped, the human-use resources the need protecting must be certified by a local or regional policy maker. These resources are often extremely vulnerable to seasonal changes due to ex. fishing and tourism. For this category there are also a set of symbols available to demonstrate their importance on ESMs.


Estimating the volume of a spill

By observing the thickness of the film of oil and its appearance on the surface of the water, it is possible to estimate the quantity of oil spilled. If the surface area of the spill is also known, the total volume of the oil can be calculated. Oil spill model systems are used by industry and government to assist in planning and emergency decision making. Of critical importance for the skill of the oil spill model prediction is the adequate description of the wind and current fields. There is a worldwide oil spill modelling (WOSM) program. Tracking the scope of an oil spill may also involve verifying that hydrocarbons collected during an ongoing spill are derived from the active spill or some other source. This can involve sophisticated analytical chemistry focused on finger printing an oil source based on the complex mixture of substances present. Largely, these will be various hydrocarbons, among the most useful being polyaromatic hydrocarbons. In addition, both oxygen and nitrogen heterocyclic hydrocarbons, such as parent and alkyl homologues of
carbazole Carbazole is an aromatic Heterocyclic compound, heterocyclic organic compound. It has a tricyclic structure, consisting of two six-membered benzene rings fused on either side of a five-membered nitrogen-containing ring. The compound's structure is ...
, quinoline, and
pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakl ...
, are present in many crude oils. As a result, these compounds have great potential to supplement the existing suite of hydrocarbons targets to fine-tune source tracking of petroleum spills. Such analysis can also be used to follow weathering and degradation of crude spills.


See also

* Automated Data Inquiry for Oil Spills * Environmental issues with petroleum * Environmental issues with shipping * LNG spill * Storm oil * Low-temperature thermal desorption * National Oil and Hazardous Substances Pollution Contingency Plan * Ohmsett (Oil and Hazardous Materials Simulated Environmental Test Tank) * Oil Pollution Act of 1990 (in the US) *
Oil well An oil well is a drillhole boring (earth), boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produ ...
* Penguin sweater * Project Deep Spill, the first intentional deepwater oil and gas spill * '' Pseudomonas putida'' (used for degrading oil) * S-200 (fertilizer) * ShoreZone *
Spill containment Spill containment is where spills of chemicals, oils, sewage etc. are contained within a barrier or drainage system rather than being absorbed at the surface. One method is to use an inflatable stopper or pneumatic bladder which is inserted into t ...
* Tarball


References


Further reading

*Nelson-Smith, ''Oil Pollution and Marine Ecology'', Elek Scientific, London, 1972; Plenum, New York, 1973 *''Oil Spill Case Histories 1967–1991'', NOAA/Hazardous Materials and Response Division, Seattle, WA, 1992 *Ramseur, Jonathan L
''Oil Spills: Background and Governance''
Congressional Research Service The Congressional Research Service (CRS) is a public policy research institute of the United States Congress. Operating within the Library of Congress, it works primarily and directly for Member of Congress, members of Congress and their United S ...
, Washington, DC, September 15, 2017 {{authority control Technology hazards Bird mortality Ocean pollution Product safety scandals Road hazards Disasters in Nigeria