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Petroleum and the Environment - Part 4: The Terrestrial Environment

GLY 4241 - Lecture 18 Fall, 2018

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Sandy Creek Spill

• An oil line operated by the Texas-based company known as Plains All American Pipeline, LP broke, sending an estimated 350 barrels of oil into a small stream near the Sandy Creek Wildlife Management Area, inside Homochitto National Forest, in far eastern Adams County, Mississippi

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Styrene Accident

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Floaters and Sinkers

Terrestrial Petroleum Exploitation

• The Former Soviet Union has many petroleum wells and pipelines. These facilities for many years have had a reputation

for causing environmental problems which include impacts on indigenous peoples and on the environment

Examples of impacts on people include:• Social impacts

• Visual impacts

• Noise impacts

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Environmental Impacts

• Environmental impacts may include: Air quality Hydrology Vegetation Animals Biological diversity

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Former Soviet Union Pollution

• Khanty-Mansiiskii Autonomous Okrug, West Siberia, is the site of one of the world's most extensive petroleum developments

• There are over 3,000 pipeline breaks a year in Western Siberia; often these are "cleaned up" by burning off the spilled oil, the fire frequently spreading to the forest.

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Komi Region, Russia

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Wetlands, Northern Russia

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Usinsk Map

Fuel Properties

• Crude oil is a mixture of many components.

• Typical crude oil contains less than 20% of the components usually found in gasoline.

• Gasoline is one of the most desirable products made from crude oil, so several strategies have been developed to increase the gasoline fraction and other fuel components from crude oil. One process simply involves heating the crude oil in the absence of

oxygen. Although hydrocarbons are stable molecules, when heated to high

enough temperatures (well beyond their boiling points) the larger hydrocarbon molecules will crack to form smaller components

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Fuel Combustion

• Fuels must have certain properties to burn well in engines

• Some hydrocarbons burn much better than other in engines

• One undesirable type of combustion produces ‟knocking," which can damage an engine The compound isooctane (2,2,4 trimethylpentane) burns well with

no knocking It is used as a standard in rating a fuel's combustion properties Isooctane is assigned an arbitrary rating of 100 on the octane scale N-heptane, which burns poorly, has an octane rating of 0 Various fuels can then be tested and compared with mixtures of

isooctane and n-heptane.

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Isomerization & Aromatization• Refineries need to convert n-alkanes to isoalkanes, which is

accomplished by isomerization. When n-pentane is heated to 100GC in the presence of aluminum

chloride, it is converted to isopentane

• Another process is aromatization If heptane is heated over platinum, it forms toluene and hydrogen All aromatization reactions involve dehydrogenation The hydrogen generated can be used in other parts of the refining

process Toluene has significantly better combustion properties than heptane Thus, both isomerization and aromatization make better fuels from

crude oil

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Gasoline Spill Danger• Aromatics are the most soluble components of crude oil• Branched alkanes also exhibit increased solubilities• Even the straight alkane chains are more soluble when short, as

they are in gasoline• Diesel and jet fuels contain more straight chain hydrocarbons

than gasoline• Additives put into gasoline are usually quite soluble• Gasoline, and other fuel spills, are apt to taint groundwater to a

much greater extent than crude oil would• In addition, the viscosity of gasoline and other fuel is lower than

crude oil, so they flow through the ground faster

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Immiscible Fluids

Spreading of the Spill

• The water opposes further downward sinking, so the hydrocarbon spreads laterally, forming a lens on top of the water

• Assuming no hydrologic gradients are present (almost impossible) the lens will spread until all pressures are balanced

• In reality, hydrologic gradients are going to introduce heterogeneities into the system and will probably force the lens to flow in a certain direction

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New Habitats• Introduction of the hydrocarbon makes new habitats in the ground.

This can introduce stress for the microorganisms. In the hydrocarbon-saturated zone, the microorganisms face the toxicity of the

hydrocarbon. In addition water flow in this area is reduced, which slows the delivery of

nutrients. Microbial growth and metabolism are slowed (Chapelle, 1993).

• Above the zone of hydrocarbon saturation, the vadose zone will be filled with the volatile components of the hydrocarbon The vadose zone will often be saturated with hydrocarbon components, and

oxygen will be present. An aerobic metabolism may operate, and many microbes will flourish with this

enhanced ‟food” supply.

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Hydrocarbon Lens Effects

• Water may be a limiting factor for growth in this zone • In the water below the hydrocarbon lens, the water will be at

residual saturation with respect to all the hydrocarbon components

• Further away from the lens there will be a hydrocarbon gradient, but the water will not be at saturation

• This zone is also favorable for microbial growth, particularly at a distance from the hydrocarbon-water interface

• Water and nutrients are abundant, and the toxic effects may not be too severe

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Experimental Work

• Dunlap and Beckmann conducted an experiment, placing four hundred milliliters of either kerosene, diesel, or fuel oil above four liters of deionized water in a sealed container

• They let the mixture stand for twenty-two days, then analyzed the hydrocarbon contents of the water using a gas chromatograph

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Hydrocarbon Concentration in Deionized Water in μG/l

• Although BTEX (benzene, toluene, ethylbenzene, and xylene) made up only about 3% of the original fuel, it dominates the dissolved hydrocarbons in the water

Aliphatic Hydrocarbon Degradation

• N-alkanes with a chain-length exceeding 10 are assimilated into cells and are oxidized more readily than short-chain n-alkanes Methane is an exception to this rule, since it is oxidized

via a different biochemical path

• Saturated aliphatic hydrocarbons are degraded faster than unsaturated aliphatic hydrocarbons

• Straight-chain hydrocarbons are degraded faster than branched chain varieties

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Aromatic Hydrocarbon Properties

• Aromatic hydrocarbons are of special interest because of their high solubilities and their biochemical properties

• Many aromatics are known potent carcinogenic agents

• Coal tar was discovered to cause cancer when applied to mouse skin in 1930 Benzo[a]pyrene was later discovered to be the active carcinogen.

• Benzene is carcinogenic The maximum legal limit for benzene in drinking water is 0.005

mg/l, or 5 ppb

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Evidence for Benzene Biodegradation

• Hadley and Armstrong examined more than 7000 water supply wells in California for evidence of chemical contamination

• It was known that thousands of underground storage tanks had leaked over the past 50 years, so it was anticipated that petroleum hydrocarbon contamination, especially by benzene, would be common

• Yet little evidence of benzene contamination was found• They examined possible benzene removal processes and

concluded the biodegradation was the most likely cause of the absence of benzene

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Bacterial Degradation

• David Gibson and colleagues that Pseudomonas putida can oxidize benzene, and can growth on ethylbenzene and toluene The mechanism involves oxidation of benzene to catechol, or cis

dihydroxy benzene It appears that catechol is an intermediate product in the breakdown of

benzene and many other aromatic hydrocarbons

• The genera Acinetobacter, Alcaligenes, Bacillus, Nocardia, and Pseudomonas can break down catechol

• Polycyclic aromatic hydrocarbons (PAHs), such as naphthalene and phenanthrene, have also been shown to undergo biodegradation PAH compounds are also known carcinogens and possible mutagens

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Benzene in Sandy Aquifer• Barker et al. reported on a field study involving injection of

benzene, toluene, and xylene into a sandy water table aquifer Eighteen hundred liters of groundwater were spiked with enough

hydrocarbons to produce a concentration of 2.4 mg/l of benzene, 1.8 mg/l of toluene, and 1.1 mg/l each of para-, meta-, and ortho-xylene

In addition the water was spiked with 1280 mg/l of chloride to act as a conservative tracer

The contaminant plume was monitored for one and a half years

As expected, the plume moved down the hydrologic gradient

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Sandy Aquifer Results• After 53 days, the chloride plume had moved about 5 meters,

and was three times the original size

• Benzene was about the same

• The toluene plume had shrunk, and after 108 days the toluene plume had disappeared

• Xylene isomers behaved similarly to toluene and were essentially gone after 108 days

• The benzene plume shrank considerably compared with the chloride plume, but traveled with it

• This rules out the possibility of sorption of benzene on the soil

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Relative Rates of Degradation

• The relative rates of degradation were: xylene > toluene > benzene

• Among the xylene isomers: p-xylene > m-xylene > o-xylene.

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Anaerobic Breakdown

• Difficult since hydrocarbons have no oxygen, sought by anaerobic organisms

• Most groundwater systems, even some shallow ones, are anaerobic

• Reinhard et al. (1984) studied a contaminated anaerobic groundwater system. Findings; xylenes were being removed, processes other than degradation were ruled out

• Wilson et al. (1986) directly demonstrated anaerobic biodegradation They used 14C labeled toluene and found 14CO2 produced under

anaerobic conditions

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Bemidji Pipeline

• In August 1979, a pipeline carrying crude oil burst and spilled about 100,000 gallons of oil onto a glacial outwash aquifer The aquifer was at the water table The glacial sediments lacked natural organic matter,

and the water was saturated in dissolved oxygen ( 10 ∼mg/l)

Crude oil formed a lens atop the water Soluble components (mainly BTEX) rapidly dissolved

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Bemidji Spill

Anaerobic Degradation Method• Lovley and Lonergan showed that toluene is reduced in steps, with

Fe3+ as the sole electron acceptor

• The process is toluene to benzyalcohol (C6H5CH3OH) to benzaldehyde (C6H5CHO) to benzoate (C6H5COOH) to carbon dioxide

• In the process 36 ferric ions are converted to ferrous iron• The microorganism responsible is the anaerobic bacteria GS-15• Like oxygen, the ferric iron supply was depleted, and other

organisms continued the biodegradation• This was the first documented case of a ferric ion reducer completely

degrading an organic compound to carbon dioxide

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Bemidji Spill Studies

• BTEX compounds were shown to be rapidly depleted near the oil lens Samples were taken at the end of the oil lens and ten

meters down gradient from the oil lens Benzene, toluene, and all the xylene isomers were

observed to decrease in the first ten meters down gradient from the spill

Toluene and the xylenes disappeared almost entirely Conditions in this part of the plume were anaerobic

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Bemidji Spill Degradation Order

• The order of xylene degradation was: o-xylene > m-xylene > p-xylene.

• Ethylbenzene was only slightly degraded in the anaerobic part of the plume

• Once the conditions became aerobic, both ethylbenzene and benzene were rapidly degraded

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Petroleum Spill Studies

• The study of petroleum spills has been attracting much research interest and knowledge is growing rapidly

• Many different cleanup methods, including bioremediation, have been and are being developed

• It should be noted that bioremediation has not been employed a great deal, but does enjoy the advantage of not doing additional harm to the environment as many other methods do

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Songhua River near Harbin,

China• Iced River contains a

benzene spill

Manager’s Response

• Managers did nothing to warn the public even though they knew the risks

• Wang Wei, vice-mayor of Jilin City and the local environmental chief, said, “It will not cause large-scale pollution"

• Technicians found levels of benzene, dianil, nitrobenzene and dimethyl benzene up to 100 times normal levels in the Songhua, within a day of the accident

• As fish were dying and the contamination drifting downstream, nobody told villagers and fishermen along the 236 miles of the Songhua between Jilin and the large city of Harbin, China, home to four million people.

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Map of Benzene Spill

• Seattle Times Graphic on benzene spill (left)

• Bloomberg graphic (below)

UNEPMR Report

• “The mission team noted that nitrobenzene (and possibly other chemicals that may have been released) is heavier than water and would sink to the bottom of the river. It will move downstream with the pollution plume but at a slower rate and may even fall behind and/or remain in some locations. It is therefore important to monitor bottom water (just above the sediment), the sediment itself, benthic organisms and bottom feeders to determine the levels and impacts. It has the potential to be damaging because it may be concentrated particularly in the higher reaches of the river closer to the accident site and because it is only sparingly soluble in water.”

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Effects in Russia

• On Monday, December 19, 2005 an increase in benzene was detected in the Amur River in Russia. Khabarovsk, a city of 580,000, braced for the arrival of the toxic

mix of chemicals. On December 25 2005, the toxic spill reached Khabarovsk It flowed through the city for the period of 5 days Later, it passed through Komsomolsk-na-Amure between January

12-16, 2006 The total length of the toxic spill was 180 kilometers A total of about seventy Russian towns and villages were affected

by the spill.

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Oil Sand Deposits in

Alberta• Bitumen in

Athabascan “tar” sands

• Proven reserves of about 170 billion barrels

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Earth Observer Satellite Photo

• (From the website)The mines follow the course of the Athabasca River, the dark brown ribbon of water that runs down the center of the image. The river is essential to the operation. Over the course of its very long lifetime, the river has eroded through the sediment that once covered the oil deposit, gradually bringing it close to the surface. Without the river, the oil sands would likely be buried beneath a thick layer of earth.

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Bitumen Extraction

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Oil Sands Photos

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• Photos from Alberta government brochure

Bitumen

• Bitumen is some of the, “ugliest stuff you ever saw...contaminated, non-homogeneous, and ill-defined....Bitumen is five percent sulfur, one percent nitrogen, and 1000 parts per million heavy metals. Its viscosity is like tar on a cold day. That’s ugly.”

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Quote from Dr. Steven Kuznicki

National Academy of Sciences Report

• “that the oil sands industry releases the 13 elements considered priority pollutants (PPE) under the US Environmental Protection Agency’s Clean Water Act, via air and water, to the Athabasca River and its watershed. In the 2008 snowpack, all PPE except selenium were greater near oil sands developments than at more remote sites. Bitumen upgraders and local oil sands development were sources of airborne emissions.

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NAS Report 2• Concentrations of mercury, nickel, and thallium in

winter and all 13 PPE in summer were greater in tributaries with watersheds more disturbed by development than in less disturbed watersheds. In the Athabasca River during summer, concentrations of all PPE were greater near developed areas than upstream of development. At sites downstream of development and within the Athabasca Delta, concentrations of all PPE except beryllium and selenium remained greater than upstream of development.

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NAS Report 3• Concentrations of some PPE at one location in

Lake Athabasca near Fort Chipewyan were also greater than concentration in the Athabasca River upstream of development. Canada’s or Alberta’s guidelines for the protection of aquatic life were exceeded for seven PPE—cadmium, copper, lead, mercury, nickel, silver, and zinc—in melted snow and/or water collected near or downstream of development.”

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Oil Sands Photos

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