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Oli Pollution(OP)

Dr. Hussein EL-shafei

2011-2012

Introduction

Oil, or petroleum, is a complex mixture of various hydrocarbons and rock minerals found below the earth's surface. The oil that is extracted from the ground is referred to as crude oil. Crude oil is then refined to make gas, kerosene, diesel fuel, jet, fuel and propane. As a raw material it can be used to make synthetic materials such as plastic, solvents, pesticides, and refrigerants. Despite all of the uses that we have for oil, it can be hazardous to the environment and ecosystem. The hydrocarbons that make up the oil are highly toxic. Crude oil also contains small amounts of sulfur and nitrogen, which are gases that can cause harm to the environment. One of the biggest effects of oil and oil extraction, and often the most visible, is the effect on the marine ecosystems. This ecosystem can be impacted in a number of ways. Crude oil is drilled and extracted from beneath the earth's surface. It is then transported through pipelines in the ocean or by huge oil tankers that transport the oil to importing countries. Occasionally, a spill can occur. This can dramatically affect the marine ecosystem, depending on the severity, duration, and cleanup efforts. Fish, mammals, sea birds, and sea plants all can be killed because of an oil spill. If the toxic nature of the chemical does not kill them, they can be affected in other ways. In some areas where there has been an oil spill, we see little biodiversity as species have been killed off. Crude oil is used to make refined products such as gasoline and diesel fuel. Vehicle exhaust from these products is one of the biggest contributors to air pollution. Burning oil releases carbon dioxide, which causes global warming. Global warming may lead to world-wide climate change, which scientists believe may have a negative effect on our environment. Along with this, sulfur dioxide, a trace ingredient in crude oil, is a cause of acid rain which then pollutes our ecosystem even further. At the point where crude oil is extracted from the ground, gasses can become trapped beneath the surface of the earth. Occasionally, this can cause an explosion, which would essentially lead to an oil geyser. This has the potential to contaminate soil, plant life, and other organisms in the area. Oil can than seep into underlying groundwater affecting us as humans. Since oil in its various forms is the primary transportation fuel, runoff from roadways can also contaminate the soil and ecosystem, destroying plants and other organisms.

What is the Pollutants(Pollution):

A pollutant may be considered as any substance, usually an unwanted by-product or waste, that is released into the environment as a result of (human) activities that alter the chemical, physical and biological characteristics of the environment. These substances may be found in any of the solid, liquid or gas phases. Many air pollutants occur as gases or vapors, but some are very tiny solid particles: dust, smoke, or soot. Smog: A mixture of pollutants, principally ground-level ozone, produced by chemical reactions in the air. A major portion of smog-formers comes from burning petroleum-based fuels such as gasoline, but also include volatile organic compounds that are found in products such as paints and solvents. Smog can harm health, damage the environment and cause poor visibility. Their long-term effects are difficult to predict and depend upon future human or cultural judgments.

Physical Effects of Pollution

Pollution affects air, water and soil. VisionsofAmerica/Joe Sohm/Photodisc/Getty Images

The effects of pollution from agriculture, industry, fossil fuels and consumption include physical damage to buildings and infrastructure, and biological damage to ecosystems. As pollution accumulates in air, water and soil, the global ecosystem from plants to animals to human beings suffers the effects.

Warning:

At some point in their life cycle, over 70 percent of terrestrial animal species are dependent upon water. Yet, despite the warnings, water pollution continues. Sewage overflows, legal or not, continue to dump bacteria, parasites, and toxic chemicals into waterways.

Coastal environments continue to be imperiled by oil spills, killing wildlife and causing millions of dollars in property damage. Unless measures are taken, the very water we drink is in danger.

Pollution control

Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil. Without pollution control, the waste products from consumption, heating, agriculture, mining, manufacturing, transportation and other human activities, whether they accumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control

Part 1

Fate of the Oil

A squid after an oil spill

Fate of spilt oil

Recognition of spilt oil at sea or on the shoreline may be the first indication of an oil spill. Depending on the quantity and type of oil involved, a clean-up response may have to be organised for removing the oil and protecting sensitive areas nearby.

The fate of spilt oil depends on a number of factors, such as the

1- Amount of oil spilled;

2- Its initial physical and chemical characteristics;

3- The prevailing weather and sea conditions;

4- Whether the oil remains at sea or comes ashore.

Once spilled at sea, the natural tendency for the oil will be to spread, break up and become dissipated over time.

This dissipation is a result of a number of chemical and physical processes acting on the spilt oil. These processes are collectively referred to as weathering.

In considering the fate of spilled oil at sea and potential clean-up and response techniques, the persistence of the oil in the environment should be taken into account.

The effect of oil spills can be far reaching, posing both an

1- Environmental

2- Economic threat.

3- Recreational activities,

4- Local industry, fisheries, and Marine life are among the resources that can be adversely affected by oil spills.

The recovery of the environment after a spill depends on a variety of factors such as the

1- Type and amount of oil spilled;

2- The biological and physical characteristics of the affected area;

3- Time of year and weather conditions,

4- Notably the clean-up and response strategy used

Typical environmental impacts range from toxicity to smothering effects.

Spills of chemicals and other Hazardous and Noxious Substances (HNS) may also present a threat to the environment.

The behaviour and fate of spilled HNS will depend on its chemical and physical properties. Its impact will also vary according to local conditions.

What is the oil:

Oil is a general term used to denote petroleum products which mainly consist of hydrocarbons.

Crude oils are made up of a wide spectrum of hydrocarbons ranging from very volatile, light materials such as propane and benzene to more complex heavy compounds such as bitumens, asphaltenes, resins and waxes.

Refined products such as petrol or fuel oil are composed of smaller and more specific ranges of these hydrocarbons.

Oil, when spilled at sea, will normally break up and be dissipated or scattered into the marine environment over time.

This dissipation is a result of a number of chemical and physical processes that change the compounds that make up oil when it is spilled. The processes are collectively known as weathering.

Oils weather in different ways. Some of the processes, like natural dispersion of the oil into the water, cause part of the oil to leave the sea surface, whilst others, like evaporation or the formation of water in oil emulsions, cause the oil that remains on the surface to become more persistent.

The way in which an oil slick breaks up and dissipates depends largely on how persistent the oil is.

1-Non-persistent oils

Light products such as kerosene tend to evaporate and dissipate quickly and naturally and rarely need cleaning-up. These are called non-persistent oils.

2-Persistent oils

In contrast, persistent oils, such as many crude oils, break up and dissipate more slowly and usually require a clean-up response.

Physical properties such as the density, viscosity and pour point of the oil all affect its behaviour.

Dissipation does not occur immediately. The time this takes depends on a series of factors, including the

1-Amount and type of oil spilled,

2-Tthe weather conditions

3- Whether the oil stays at sea or is washed ashore.

Sometimes, the process is quick and on other occasions it can be slow, especially in sheltered and calm areas of water.

Most of the weathering processes, such as

1- Evaporation,

2- Dspersion,

3- Dissolution

4- Sedimentation, lead to the disappearance of oil from the surface of the sea.

whereas others, particularly the formation of water-in-oil emulsions ("mousse") and the accompanying increase in viscosity, promote its persistence.

The speed and relative importance of the processes depend on factors such as

1- The quantity and type of oil,

2- The prevailing weather and sea conditions,

3- Whether the oil remains at sea or is washed ashore.

Ultimately, the marine environment assimilates spilled oil through the long-term process of biodegradation.

The main processes that cause an oil to weather are described below and summarised in the following diagram.

Figure 1: Fate of oil spilled at sea showing the main weathering processes

1-Spreading

As soon as oil is spilled, it starts to spread out over the sea surface, initially as a single slick.

The speed at which this takes place depends to a great extent upon the viscosity of the oil. Fluid, low viscosity oils spread more quickly than those with a high viscosity. Nevertheless, slicks quickly spread to cover extensive areas of the sea surface.

Spreading is rarely uniform and large variations in the thickness of the oil are typical. After a few hours the slick will begin to break up and, because of winds, wave action and water turbulence, will then form narrow bands or windrows parallel to the wind direction.

The rate at which the oil spreads is also determined by the prevailing conditions such as

1- Temperature,

2- Water currents,

3- Tidal streams

4- Wind speeds.

The more severe the conditions, the more rapid the spreading and breaking up of the oil.

2-Evaporation

Lighter components of the oil will evaporate to the atmosphere. The amount of evaporation and the speed at which it occurs depend upon the volatility of the oil.

Oil with a large percentage of light and volatile compounds will evaporate more than one with a larger amount of heavier compounds.

For example, petrol, kerosene and diesel oils, all light products, tend to evaporate almost completely in a few days whilst little evaporation will occur from a heavy fuel oil.

In general, in temperate conditions, those components of the oil with a boiling point under 200ºC tend to evaporate within the first 24 hours.

Evaporation can increase as the oil spreads, due to the increased surface area of the slick.

1- Rougher seas,

2- High wind speeds

3- High temperatures also tend to increase the rate of evaporation and the proportion of an oil lost by this process.

3-Dispersion

Waves and turbulence at the sea surface can cause all or part of a slick to break up into fragments and droplets of varying sizes. These become mixed into the upper levels of the water column. Some of the smaller droplets will remain suspended in the sea water while the larger ones will tend to rise back to the surface, where they may either coalesce with other droplets to reform a slick or spread out to form a very thin film.

The oil that remains suspended in the water has a greater surface area than before dispersion occurred. This encourages other natural processes such as dissolution, biodegradation and sedimentation to occur.

The speed at which an oil disperses is largely dependent upon the

1- Nature of the oil and

2- The sea state, and

3- Occurs most quickly if the oil is light and of low viscosity and

4- If the sea is very rough.

4-Emulsification

An emulsion is formed when two liquids combine, with one ending up suspended in the other. Emulsification of crude oils refers to the process whereby sea water droplets become suspended in the oil. This occurs by physical mixing promoted by turbulence at the sea surface.

The emulsion thus formed is usually very viscous and more persistent than the original oil and is often referred to as chocolate mousse because of its appearance.

The formation of these emulsions causes the volume of pollutant to increase between three and four times. This slows and delays other processes which would allow the oil to dissipate.

Oils with an asphaltene content greater than 0.5% tend to form stable emulsions which may persist for many months after the initial spill has occurred.

Those oils containing a lower percentage of asphaltenes are less likely to form emulsions and are more likely to disperse.

Emulsions may separate into oil and water again if heated by sunlight under calm conditions or when stranded on shorelines.

5-Dissolution

Water soluble compounds in an oil may dissolve into the surrounding water. This depends on the composition and state of the oil, and occurs most quickly when the oil is finely dispersed in the water column.

Components that are most soluble in sea water are the light aromatic hydrocarbons compounds such as benzene and toluene. However, these compounds are also those first to be lost through evaporation, a process which is 10 -100 times faster than dissolution. Oil contains only small amounts of these compounds making dissolution one of the less important processes.

6- Oxidation

Oils react chemically with oxygen either breaking down into soluble products or forming persistent compounds called tars.

This process is promoted by sunlight and the extent to which it occurs depends on the type of oil and the form in which it is exposed to sunlight. However, this process is very slow and even in strong sunlight, thin films of oil break down at no more than 0.1% per day.

The formation of tars is caused by the oxidation of thick layers of high viscosity oils or emulsions.

This process forms an outer protective coating of heavy compounds that results in the increased persistence of the oil as a whole.

Tar balls, which are often found on shorelines and have a solid outer crust surrounding a softer, less weathered interior, are a typical example of this process.

-Sedimentation/Sinking7

Some heavy refined products have densities greater than one and so will sink in fresh or brackish water. However sea water has a density of approximately 1.025 and very few crudes are dense enough or weather sufficiently, so that their residues will sink in the marine environment.

Sinking usually occurs due to the adhesion of particles of sediment or organic matter to the oil. Shallow waters are often laden with suspended solids providing favourable conditions for sedimentation.

Oil stranded on sandy shorelines often becomes mixed with sand and other sediments. If this mixture is subsequently washed off the beach back into the sea it may then sink. In addition, if the oil catches fire after it has been spilled, the residues that sometimes form can be sufficiently dense to sink.

8-Biodegradation

Sea water contains a range of micro-organisms or microbes that can partially or completely degrade oil to water soluble compounds and eventually to carbon dioxide and water.

Many types of microbe exist and each tends to degrade a particular group of compounds in crude oil. However, some compounds in oil are very resistant to attack and may not degrade.

The main factors affecting the efficiency of biodegradation, are the

1- Levels of nutrients (nitrogen and phosphorus) in the water,

2- Temperature

3- Level of oxygen present.

As biodegradation requires oxygen, this process can only take place at the oil-water interface since no oxygen is available within the oil itself.

The creation of oil droplets, either by natural or chemical dispersion, increases the surface area of the oil and increases the area available for biodegradation to take place.

9- Combined processes

The processes of spreading, evaporation, dispersion, emulsification and dissolution are most important during the early stages of a spill whilst oxidation, sedimentation and biodegradation are more important later on and determine the ultimate fate of the oil.

To understand how different oils change over time whilst at sea, one needs to know how these weathering processes interact.

To predict this, some simple models have been developed based on oil type.

Oils have been classified into groups roughly according to their density - generally, oils with a lower density will be less persistent.

However some apparently light oils can behave more like heavy ones due to the presence of waxes. Although simple models cannot predict the changes an oil undergoes very precisely, they can provide clues about whether an oil is likely to dissipate naturally or whether it will reach the shoreline.

This information can be used by spill responders to decide upon the most effective spill response techniques and whether such techniques can be initiated quickly enough.

The concept of persistence in relation to oil spills probably originated after the TORREY CANYON incident in 1967.

This is the time when discussions first arose regarding various new measures to protect the marine environment and to manage marine oil spills, particularly in relation to liability and compensation.

Classification of Oil:

1-Persistent oils include crude oils, fuel oils, heavy diesel and lubricating oils.

2- Non-persistent oils include gasoline, light diesel oil and kerosene.

1- Persistent oils:

Generally contain a considerable proportion of heavy fractions or high-boiling material. They do not dissipate quickly and will therefore pose a potential threat to natural resources when released to the environment.

Impacts from Persistent oils:

1-Impacts to wildlife

2- Smothering of habitats

3-Oiling of amenity beaches.

2- Non-persisten oils:

In contrast are generally of a volatile nature and are composed of lighter hydrocarbon fractions. When released into the environment they will dissipate rapidly through evaporation. As a result, spills of these oils rarely require a response but when they do, clean-up methods tend to be limited.

Impacts from non-persistent oils may include, for example,

1-Effects on paint coatings in marinas and harbours

2- At high concentrations - acute toxicity to marine organisms.

The international compensation regime for oil spills only applies to spills of “persistent” oil. Whilst this term is not precisely defined in any of the conventions, the International Oil Pollution Compensation Funds (IOPC Funds) have developed guidelines which are widely accepted.

Under these guidelines an oil is considered non-persistent if:

1- at the time of shipment at least 50% of the hydrocarbon fractions, by volume, distil at a temperature of 340°C (645°F) and

2- at least 95% of the hydrocarbon fractions, by volume, distil at a temperature of 370°C (700°F) when tested in accordance with the American Society for Testing and Materials (ASTM) Method D86/78 or any subsequent revision thereof.

However, this definition is based on distillation characteristics of oils under standard laboratory conditions. It may not, therefore, fully reflect the behaviour of oil in the environment, where factors such as burial in sediments can lead to the long-term persistence of oils that would normally be defined as non persistent.

What is the oil spill:

An oil spill is a release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution.

Oil spills include releases of crude oil from

1- Tankers,

2- Offshore platforms,

3- Drilling rigs and wells,

As well as spills of refined petroleum products (such as gasoline, diesel) and their by-products, and heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil. Spills may take months or even years to clean up.

The term often refers to marine oil spills, where oil is released into the ocean or coastal waters.

How the oil reach to the environment ?

Crude oil is drilled and extracted from beneath the earth's surface. It is then transported through pipelines in the ocean or by huge oil tankers that transport the oil to importing countries.

Occasionally, a spill can occur. This can dramatically affect the marine ecosystem, depending on the

-Severity 1

-Duration2

-Cleanup efforts3

Oil also enters the marine environment from natural oil seeps. Recently, public attention and regulation has tended to focus most sharply on seagoing oil tankers.

Coastal environments continue to be imperiled by oil spills, killing wildlife and causing millions of dollars in property damage. Unless measures are taken, the very water we drink is in danger

Types of Petroleum Compound:

1-Volatile organic compounds (VOCs)

Are gases or vapours emitted by various solids and liquids, many of which have short- and long-term adverse effects on human health and the environment.

VOCs from petroleum are toxic and foul the air, and some like benzene are extremely toxic, carcinogenic and cause DNA damage.

2-Polycyclic Aromatic Hydrocarbons (PAHs)

Most commonly associated with ship pollution are oil spills. While less frequent than the pollution that occurs from daily operations, oil spills have devastating effects. While being toxic to marine life

Polycyclic aromatic hydrocarbons (PAHs), the components in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment.

Marine species constantly exposed to PAHs can exhibit developmental problems, susceptibility to disease, and abnormal reproductive cycles.

One of the more widely known spills was the Exxon Valdez incident in Alaska. The ship ran aground and dumped a massive amount of oil into the ocean in March 1989. Despite efforts of scientists, managers, and volunteers over 400,000 seabirds, about 1,000 sea otters, and immense numbers of fish were killed.

3-What are polycyclic aromatic hydrocarbons (PAHs)?

A- Occurance

1- Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil ,coal, tar and gas, garbage, or other organic substances like tobacco or charbroiled meat.

Natural crude oil and coal deposits contain significant amounts of PAHs, arising from chemical conversion of natural product molecules, such as steroids, to aromatic hydrocarbons. They are also found in processed fossil fuels, tar and various edible oils. and are produced as byproducts of fuel burning (whether fossil fuel or biomass) PAHs are usually found as a mixture containing two or more of these compounds, such as soot.

2- Some PAHs are manufactured. These pure PAHs usually exist as colorless, white, or pale yellow-green solids.

3- PAHs few are used in medicines or to make dyes, plastics, and pesticides.

4-Polycyclic Aromatic Hydrocarbons (PAHs) are a class of very stable organic molecules made up of only carbon and hydrogen.

5- PAHs are also found in foods. Studies have shown that most food intake of PAHs comes from cereals, oils and fats. Smaller intakes come from vegetables and cooked meats.

6- They are also found in the interstellar medium, in comets, and in meteorites and are a candidate molecule to act as a basis for the earliest forms of life

Here at the astrochemistry lab we are interested in PAHs (and other related molecules because they are very common in space and as a result they can act as probes of conditions in distant regions. They light from the glow of PAHs (they emit light when excited either by heat or UV photons) has been detected coming from hot regions of space where stars are born, and around dying stars, and even from other galaxies as well. In addition, these molecules have been detected in comet and a steroidal dust and are common in meteorites.

It is believed that these molecules form in the outflows of dying carbon rich stars from which they go out into the space between the stars. Those that survive the predation of supernova shocks and cosmic rays end up in dense molecular clouds, where they condense onto microscopic ice grains. Here, these molecules undergo some chemistry that we simulate in the lab.

These compounds are of importance for those of us who are interested in the search for life in the Solar System, because sometimes (on earth) these molecules are used as biomarkers (chemicals that indicate life).

The wide range of PAHs that are seen in space would seem to make PAHs of any kind a poor sign of life, even though they are sometimes biomarkers here on Earth. What would be a good indicator of life on another planet?

4- Pollution:

These compounds are among the most widespread organic pollutants, remaining on beaches and marine environmentals for a long time after an oil spill.

1- As a pollutant, they are of concern because some compounds have been identified as carcinogenic, mutagenic, and teratogenic.

2-Recent investigations have concluced that their toxicity is up to 100 times worse than first assumed

3- Exposure to polycyclic aromatic hydrocarbons usually occurs by breathing air contaminated by wild fires or coal tar, or by eating foods that have been grilled. PAHs have been found in at least 600 of the 1,430 National Priorities List sites identified by the Environmental Protection Agency (EPA).

5-Polycyclic aromatic hydrocarbons are lipophilic, meaning they mix more easily with oil than water. The larger compounds are less water-soluble and less volatile (i.e., less prone to evaporate).

6-Because of these properties, PAHs in the environment are found primarily in soil, sediment and oily substances, as opposed to in water or air. However, they are also a component of concern in particulate matter suspended in air.

5-Human health

PAHs toxicity is very structurally dependent, with isomers (PAHs with the same formula and number of rings) varying from being nontoxic to being extremely toxic. Thus, highly carcinogenic PAHs may be small or large.

One PAH compound, benzo[a]pyrene, is notable for being the first chemical carcinogen to be discovered (and is one of many carcinogens found in cigarette smoke). The EPA has classified seven PAH compounds as probable human carcinogens:

1- benz[a]anthracene,

2- benzo[a]pyrene,

3- benzo[b]fluoranthene,

4- benzo[k]fluoranthene,

5- chrysene,

6- dibenz[a,h]anthracene,

7- and indeno[1,2,3-cd]pyrene.

PAHs known for their carcinogenic, mutagenic and teratogenic properties are benz[a]anthracene and chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, coronene, dibenz[a,h]anthracene (C20H14), indeno[1,2,3-cd]pyrene (C22H12) and ovalene.

PAHs containing up to six fused aromatic rings are often known as "small" PAHs and those containing more than six aromatic rings are called "large" PAHs. Due to the availability of samples of the various small PAHs, the bulk of research on PAHs has been of those of up to six rings.

6- Biological activity of PAH:

The biological activity and occurrence of the large PAHs does appear to be a continuation of the small PAHs. They are found as combustion products, but at lower levels than the small PAHs due to the kinetic limitation of their production through addition of successive rings. Additionally, with many more isomers possible for larger PAHs, the occurrence of specific structures is much smaller.

Aqueous solubility decreases approximately one order of magnitude for each additional ring.

PAH compounds

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