Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... …the liquid form, commonly called crude oil, but, as a technical term, petroleum also includes natural gas and the viscous or solid form... Get exclusive access to content from our 1768 First Edition with your subscription.
The petroleum industry, however, uses the American Petroleum Institute (API) gravity scale, in which pure water has been arbitrarily assigned an API gravity of 10°. Small oil spills from shipping (defined as involving quantities less than 700 tons) usually occur as a result of human errors during routine operations especially during loading and discharging.
Oil-well drilling is another potential release of petroleum hydrocarbons, estimated to account for 2% of petroleum wastes in the US (Reis, 1992). Physical changes have led to the formation of macrostructures where carbon and hydrogen are predominant. It should be pointed out that the local conditions determine the speed of the degradation.
Biodiesel has a relatively simple chemical composition compared with petroleum oil. Most other areas of the world define capacity by the weight of materials processed and record measurements in metric units; therefore, crude oil outside the United States is usually measured in metric tons. Although the chemical compositions of these mixtures are relatively simple concerning oil types, they have also attracted attention for identifying and quantifying the contaminants or the mixture for different purposes. Chemical characterisation of produced water from four offshore oil production platforms in the North Sea. This has been a problem particularly for Brent crude produced in the British North Sea, which is actively traded in the forward market, and where the number of cargoes consists of about two dozen a month. Some of it migrates up to the surface, where oil-eating microbes consume the better parts of it (creating so-called tar sands ). A barrel of API 30° light oil would weigh about 139 kg (306 pounds). These hydrocarbons have similar properties, but cycloalkanes have higher boiling points. Those elements form a large variety of complex molecular structures, some of which cannot be readily identified. He is leading a research group funded by the National Science Foundation that aims to figure out what these deep-dwelling microbes may be living off of and what influence they may have on petroleum chemistry.
As a result of the combined efforts by the tanker industry and governments largely collaborating under the auspices of International Maritime Organization (IMO), the total amount of oil entering the oceans from tankers and tanker accidents has decreased significantly during the past decades. Dispersion is highly dependent on the state of the sea and in rough seas most of an oil spill may disperse into the water column more or less instantly. Possibly the most important physical property is specific gravity (i.e., the ratio of the weight of equal volumes of a crude oil and pure water at standard conditions). Adelman, M.C.
New York, Given the pattern of modern demand (which tends to be highest for transportation fuels such as gasoline), the market value of a crude oil generally rises with increasing yields of light products. The chemistry and physical behavior of spilled oil change over time.
Large volumes of brackish contaminated water are continuously released with oil and gas production, including operations in offshore platforms (Durell et al., 2006). Crude oil fractions separated by distillation are passed on for subsequent processing into numerous products, ranging from gasoline and diesel fuel to heating oil to asphalt. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. An oil spill in the sea will undergo a series of chemical, biological, and physical processes which will lead to the degradation of the oil. Crude oil is pumped from a well in western Siberia, Russia.
Thus, seeping oil or a marine oil spill includes a wide range of compounds. Visit our corporate site.
From: Encyclopedia of Inland Waters, 2009, James G. Speight, in Reaction Mechanisms in Environmental Engineering, 2018. The value used for C (0.00024) includes the constant 0.015 after Mackay and Matsugu.8. By contrast, background concentrations of PAHs in the North Sea are around 1–45 ng l−1, or about 105–106 times lower than produced water samples (Utvik, 1999). Even when oil does form, it does not always last. Petroleum oil is toxic for most life forms and episodic and chronic pollution of the environment by oil causes major ecological perturbations. It supplies technical guidance for the following cleanup/fractionation procedures. Please refresh the page and try again. …the liquid form, commonly called crude oil, but, as a technical term, petroleum also includes natural gas and the viscous or solid form known as bitumen, which is found in tar sands. The other possibility is that these hearty bugs are actively helping to catalyze the reactions that create oil and siphoning off a bit of the remaining energy for themselves. A summary treatment of crude oil follows. Crude from more isolated wells is collected in tank trucks and taken to pipeline terminals; there is also some transport in specially constructed railroad cars. There are three primary aspects of quality: weight, indicating the amount of carbon relative to hydrogen; sulfur content, which is often referred to as sweetness (low sulfur) or sour (high sulfur); and contaminants, particularly heavy metals such as nickel and vanadium. They generally get passed up and fall to the seafloor, where they become buried under layers of sediment and eventually cooked into petroleum. When petroleum is placed in an aerobic environment (i.e., in presence of O2) it becomes a contaminant, although it can be a source of carbon and electrons if certain conditions are suitable for microorganisms. Photooxidation is recognized to particularly affect PAHs, particularly those with a peri-condensed structure (e.g., benz(a)anthracene) versus cata-condensed structure (e.g., chrysene), the former of which is considered more susceptible to UV radiation due to its larger cross-sectional area (Plata et al., 2008). Petroleum, or crude oil, is a naturally occurring liquid that originates from the Carboniferous period about 200 to 400 million years ago. Zeyu Yang, ... Carl E. Brown, in Standard Handbook Oil Spill Environmental Forensics (Second Edition), 2016. In addition to natural seepage of petroleum hydrocarbons into the sea, anthropogenic activities contribute to oil contamination resulting directly from drilling operations and transportation and indirectly, for example, through fallout from the atmosphere.
Since these compounds are polar, they are more soluble in water than the parent compounds (Payne and McNabb, 1985; Ehrhardt and Douabul, 1989; Ehrhardt and Burns, 1990; Ehrhardt et al., 1992), and therefore can be preferentially dissolved from the spilled oil. Since it is difficult to track all of the many prices for crudes according to quality differences, many contracts rely on what is called a marker crude. Photooxidation can affect whole groups of compounds (e.g., triaromatic steroids) or individual isomers (methyl-pyrenes and benzofluorenes) that are sometimes used in chemical fingerprinting spilled oils. It should be noted that during these experiments, one could see the skin formation on the unstirred oil, and this skin developed more toward the end of the 200-hour experiments.
21.5) that expose and make the available surface of the oil body much greater to the aqueous environment, in turn, making it more bioavailable and biodegradable for microorganisms.
For spills related to biodiesel or its mixture with diesel/engine oil/jet fuel, a fast screening is generally performed by GC/MS with a full scan to distinguish the spill types from pure biodiesel and its blends with refined petroleum oil. By continuing you agree to the use of cookies. At higher temperatures, these processes may degrade most of the oil in a relatively short time.
Please deactivate your ad blocker in order to see our subscription offer. HCB also have potential biotechnological applications in the areas of bioplastics and biocatalysis.
"The ultimate source of energy is the sun, and oil is just a 'battery,'" said Barry Katz, a research scientist at Chevron. As produced water has been in contact with oil for millions of years, it contains significant amounts of the most soluble petroleum compounds (Wilson, 2008). Robert Ramírez-García, ... Vijai Singh, in Phytomanagement of Polluted Sites, 2019.
This analysis has yielded important new insights into its capacity for (1) n-alkane degradation including metabolism, biosurfactant production, and biofilm formation, (2) scavenging of nutrients and cofactors in the oligotrophic marine environment, as well as (3) coping with various habitat-specific stresses. Some oils can lose from 5% to 50% of light compounds via evaporation during the first 24 h, significantly increasing viscosity within hours to a few days (Mackay and Matsugu, 1973; NRC, 2003). Generally, preliminary identification of the oil type and weathering can be readily achieved by GC/FID analysis.
"Less than 1 percent of the organic material growing in the ocean becomes hydrocarbons.". These can retard the evaporation of the compounds to a great extent. Tanker capacities vary from less than 100,000 barrels to more than 3,000,000 barrels. Receive news and offers from our other brands?