Effects to the water quality
Oils consist of a complex mixture of hydrogen and carbon which is used for fuel, lubrication, plastics manufacturing, and many other purposes. These petroleum products get into water mainly by means of accidental spills from ships, tanker trucks, pipelines, and leaky underground storage tanks
Petroleum products affect surface water, impairing water quality with hydrocarbons, salts, nutrients, a host of organic compounds, and various heavy metals. Immediately after a spill, Oil slicks on the surface water producing a thick mousse. A large portion of the oil also forms emulsions or dissolves in the water. Some heavy portions will settle into to the bottom. Oxygen can be relatively easily obtained in the slick oil spill, but the nutrients are sometimes limited. In the warm waters of the equatorial and tropical oceans, it has been observed that this evaporation will remove as much as 40% of the spill during the first 24 hr. Oil will also be oxidised by dissolved oxygen at the rate of 1 mg of oil per 3 mg of oxygen consumption. Microbial degradation will account for 2g of oil per square meter per day. Around 1% of the spilled oil will be dissolved or dispersed in water. In addition, photo-oxidation by solar radiation will also degrade a part of the oil. Thus, it can be expected that around 45-50% of any oil spill will be removed during the first 24 hr in the warm zone of the ocean. The heavier fractions of the spill will form drifting patches being split up by the prevailing winds and currents. These patches will ultimately end up as floating tar particles
Oil is an intimidating mixture of thousands of compounds, and every oil is different. All petroleum-based fuels, including the gasoline we pump into our cars, begin with crude oil that is pulled from the ground and processed at a refinery, where it is heated and separated into the different products we use. As crude oil is heated, lighter compounds evaporate and are collected and sold as gasoline, jet fuel, kerosene, diesel fuel, and lubricating oil (motor oil). Different types of oil have different environmental effects. According to the National Oceanic and Atmospheric Administration (NOAA), scientists broadly categorize oil types into "light" and "heavy." When lighter oils, such as gas and diesel, spill out onto the water, they evaporate rather quickly and only remain in the environment for a short time. They are, however, highly toxic and highly flammable. Coming in contact with the oil or breathing the fumes can kill animals and plants. The oil can also ignite and explode. Heavier oils, such as those used to power ships, are not as toxic as light oils, but they can remain in the environment for years. They can harden after coming ashore, at which point they are less toxic to plants and animals. Heavy oil spills harm plants and animals by smothering them.
Chemical Constituents Commonly Found in oil spills
| Colorless, sweet smelling liquid and vapor. Evaporates very quickly and dissolves slightly in water.
| Toluene aka Methylbenzene
| Toluene is a clear, colorless liquid and vapor that smells like gasoline. Toluene occurs naturally in crude oil.
| Ethyl benzene
| Ethyl benzene is a colorless liquid. It is highly flammable and smells like gasoline. It is naturally found in coal tar and petroleum.
| Generic alkanes(including octane,hexane, nonane)
| Alkanes are colorless liquids or vapors that smell like gasoline. They are present in crude oil and petroleum products. They are highly flammable and evaporate easily
| Xylene is a colorless, sweet-smelling liquidand vapor. It is highly flammable and evaporates easily. It occurs naturally in petroleum and coal tar.
Amoco Cadiz and Exxon Valdez
The Amoco Cadiz and Exxon Valdez oil spills caused much of the present interest--both from the public and the scientific community. Attention has been focused on the possible effects of oil spills on coastlines and...
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