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In 1989, television carried scenes of oil-soaked birds and polluted beaches after the tanker Exxon Valdez ranaground off the south central coast of Alaska. This subarctic disaster gave an indication of what hydrocarbonpollution can do farther north in the Arctic. In 1994, more television pictures, this time from Usinsk in theKomi Republic of Russia, further turned the world’s attention to the environmental impacts of oil development

in the Arctic. In one of the largest oil spills everon land, many thousands of cubic meters ofcrude oil poured from a ruptured pipeline. Oilfrom several leaks spread over the surroundingwetlands contributing to large-scale damage tothe vegetation and wildlife of the area.

In spite of the concerns raised by the Komispill, it remains difficult to determine howmuch damage it actually caused. The land sur-rounding the pipeline was severely contami-nated long before the accident and before tele-vision crews started to document environmen-tal damage from the spill. Russian pipelines areold, lack safety valves, and are plagued by con-stant leaks. Often, the oil is left flowing whilerepairs are made on a section of the pipe,because the lost oil costs less than putting in abypass and because stopping the flow mightcause the oil sitting in the pipeline to solidify.Accounts of the environment around Russianoil fields also speak of large contaminatedareas where oily water and chemicals arestored in wetlands that periodically overflowto nearby river basins.

The Russian experience is not an inevitableresult of oil exploitation in the Arctic. Otherventures show that it is possible to limit theenvironmental impact of most routine opera-tions. But as the exploitation of the hugeresources of oil and gas increases, so does therisk of serious accidents. Although more strin-gent regulation will reduce the frequency ofaccidents, incidents due to human error andtechnical deficiencies over recent decades haveshown that regulation alone cannot completelyprevent spills. Moreover, many features of theArctic environment make it likely that spillshere will have more severe consequences thanspills elsewhere.

This chapter discusses risk scenarios for oil spills in marine as well as terrestrial environments, along with theenvironmental impact of routine releases of contaminants from oil and gas exploration. Special sections of thechapter are devoted to polycyclic aromatic hydrocarbons (PAHs). Of all the contaminants associated withpetroleum production, these persistent organic pollutants present the greatest risk to environment and health.PAHs also have several other sources that contribute to their load in the environment.

Petroleum Hydrocarbons

Sources and levelsThe main environmental concern about hydro-carbon pollution stems from the exploitationand transport of oil and gas resources, but op-erational discharges of oil from ships can alsocreate local damage. Runoff from land, dis-charges in waste water, and atmospheric depo-sition contribute to the load on a regional scale.Natural oil seeps are another significant source.Operational discharges from offshore exploita-tion also contain dissolved oil components.

Oil exploration in the Arctic is expanding

The Arctic may contain some of the world’slargest petroleum reserves. These resources arelocated both on land and on the continentalshelves. The map on the opposite page shows

some of the major oil and gas fields that arecurrently used for production and those whereexploration activities are underway. The keyareas with current production are NormanWells on Canada’s Mackenzie River, the Prud-hoe Bay oilfield on Alaska’s Beaufort Sea coast,the Nenets Autonomous Okrug and the Yama-lo-Nenets Autonomous Okrug in Russia, andtwo fields on the Norwegian shelf. In addition,off-shore exploration activities are headingtoward production in the Barents Sea, off thenorthwest coast of Russia, on the Norwegianshelf of the Barents Sea, off the west coast ofGreenland, and on the North Slope of Alaska.See the table on this page.

Both exploration and production activitiescan be major sources of petroleum hydrocar-bons to the Arctic environment. The environ-mental impact of routine operations dependsto a large extent on practices for handling andtransport of oil and gas and for dischargingdrill cuttings and produced water. Hydrocar-bons are not the only concern. Operationaldischarges contain considerable amounts ofother organic contaminants and heavy metals.The table on page 6 summarizes potential im-pacts from different phases of oil exploitation.

Discharge of drill cuttingscauses environmental damage

Drilling muds are used to lubricate the drillbit,to control pressure in the well, to support andseal the walls of the bore hole, and to carrydrill cuttings to the surface. At the surface, drillmuds are normally separated from the drill cut-tings, which have usually been dumped onland or directly in the water near oil rigs. Thecuttings usually settle quickly, and in areaswith weak circulation, they can create largeaccumulations around an oil rig.

The muds are made of various mixtures of adozen substances, including special clays, oils,metals, and other compounds that may be tox-ic to biota. Water-based muds are most com-mon. In the offshore environment, water-basedmuds will spread more widely than oil-basedmuds. Certain situations require use of envi-ronmentally threatening oils as the base ofthe muds. Until the early 1980s, diesel oil wasused in such cases, but it has since been re-placed by low-aromatic mineral oils in an at-tempt to reduce environmental impacts. Recent-ly, synthetic oil fluids have partially replacedoil-based fluids, especially in off-shore drilling.

Studies of bottom fauna around oil fields onthe Norwegian shelf north of 62°N haveshown that changes are local and that harmfulbiological effects only occur in the vicinity ofthe discharges. The discharge of water-basedmuds has been observed to have slight effectson biological communities in an area of about15 square kilometers around the drilling site.Synthetic oil muds modified the bottom faunain an area of a couple of square kilometers.

146Petroleum hydrocarbons

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Canada

---------------------------------------------------------------------------------------------------------------Mackenzie Delta Reserves Estimated size:and nearshore 238-318�106 m3 oilBeaufort Sea 0.29-0.36�1018 m3 gas

---------------------------------------------------------------------------------------------------------------Tar sands at northwest ReservesMelville Island,gas on SabinePeninsula and inoffshore Hecla Fields

---------------------------------------------------------------------------------------------------------------Norman Wells, Production and pipeline Annual production:Mackenzie River to Zama, Alberta 1.3�106 m3 oil

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––United States

---------------------------------------------------------------------------------------------------------------Prudhoe Bay, Trans-Alaska Pipeline Original size:Beaufort Sea coast connects field to Port Valdez 3.1�109 m3 oil;

in south-central Alaska still commercially recoverable:1.2 �109 m3 oil

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Russia

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Nenets Autonomous Production and network Estimated annual productionOkrug, Komi Republic, of pipelines linking volume from the 18Yamal-Nenets production sites with largest companies:Autonomous Okrug national system 93�106 tonnes oil

742�1012 m3 natural gas3.4�1012 m3 casing-head gas2�106 tonnes gasoline(total Arctic production may be several times greater)

---------------------------------------------------------------------------------------------------------------Shelf areas of Barents, Exploration for oil and gasKara, and Pechora Seas

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Norway

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Norwegian Sea Production in the Draugen Estimated reserves:

and Heidrun fields 330-3330�106 m3oil equi-valents of which two-thirds valents of which two-thirds

---------------------------------------------------------------------------------------------------------------Barents Sea Exploration for oil and gas Estimated reserves:

295-1955�106 m3oil equi- valents of which two-thirdsis gas

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––GreenlandNuussuaq, Davis Strait Exploration

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Similar studies in the Beaufort Sea showed thatdischarges of water-based drilling fluids couldalter the abundance of several types of bottomanimals, but again only in a relatively limitedarea.

Land-based wells use similar drilling mudsas off-shore drilling activities, but differentmethods of waste disposal. On land, usedmuds are often dumped into sumps. The effi-ciency of containment varies widely, and it isnot uncommon that groundwater, vegetation,soil, and biota are contaminated. The damageis usually restricted to an area within a few

hundred meters of the sump. In some cases inRussia, the waste is dumped directly into land-scape depressions rather than into speciallyconstructed dumps, resulting in environmentaldamage to larger areas.

Adherence to strict regulations and the useof improved waste management technologyare essential to limit the environmental conse-quences of drill muds and cuttings. New prac-tices, including narrower bore holes and com-bining exploratory and production wells, alsohelp reduce the amount of waste.

Gas production

Oil and gas production

Navigation routes

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147Petroleum

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Major areas of oil andgas activities in theAMAP region.

OIL-RELATED ENVIRONMENTAL IMPACT.––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Activity Kind of pollution Main chemicals Sites affected Potential effect targets––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Exploration phase––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Rigging Physical disturbance, None Locally on site and Soils, permafrost stability, bottom sedi-noise, physical presence along transport routes ments, vegetation, fauna, behavioral

patterns-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Seismics Physical disturbance, noise None Locally on site Aquatic organisms (e.g. fish larvae)-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Exploratory Discharges of drill Water-based drilling Locally to Soil and sediment contamination levels,drilling cuttings and chemicals fluids, anti-corrosion regionally vegetation, bottom and near-bottom

agents, scale inhibitors, fauna, amenities, and other environ-cementing agents, mental usagecompletion chemicals,and others

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Accidental spills Oil discharge Hydrocarbons Local (on land) Contamination levels (soils, snow, surface(blowouts) dispersants to long-range waters, ice, sediments), vegetation and

(rivers, lakes, and sea) fauna, amenity values, and tourism––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Construction phase––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Removal of Physical disturbance, None Locally on site Habitat diversity, quality, andvegetation noise availability, erosion, permafrost

stability (peat removal), animalbehavior

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Technical Physical disturbance, None Locally on site Habitat quality and access,installations physical presence permafrost stability

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Excavation and Physical disturbance None On-site soils and Water courses and drainage patterns,infill of soils and downstream surface- ground and surface water, soil and sediments and groundwater sediment organisms

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Road/trail Physical disturbance, None Locally Access, migration routes, erosion, construction noise, physical presence vegetation, animal behavior

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Use of helicopters Noise, exhaust discharge Combustion products Along routes Contamination levels of water,and supply soils and organisms, biotope quality,vessels behavioral patterns

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Dredging and Physical disturbance, None Pipeline trajectory Soils, bottom sediments, vegetation,construction noise, physical presence and adjacent areas fauna, behavioral patterns (migration)pipelines

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Production phase

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Well drilling Discharges of Drilling fluids, anti- Locally to regionally Soil and sediment contamination

drill cuttings corrosion agents, scale levels, land access, vegetation,and chemicals inhibitors, cementing bottom and near-bottom fauna

agents, completionchemicals, and others

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Well production Discharge of production Production water, scale Local soils, local/re- Contamination level of soil and waters,

water and chemicals inhibitors, flocculant gional surface- and vegetation, land fauna and marineagents, biocides, anti- groundwater, surface- pelagic organismscorrosion agents, gas and shallow sea water,treatment chemicals possibly sea floor

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Other operational Wash and drainage water, Hydrocarbons, Soils, local watersheds, Contaminant levels, water vegetationaqueous waste ballast water, sanitary chemicals, sewage shallow sea water and fauna, waterfowl and seabirdseffluents outlets, operation spills

and leakages-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Flaring, venting and Air emissions CO2 and CO, Wide range Greenhous gas and ozone levels,purging, energy pro- methane, VOC, NOx, due to soil, water, sediment and organismduction (combustion) SO2 and H2S halons, atmospheric contaminant levels, human health,fire protection tests, ozone-depleters transport vegetation and faunaexhaust and dust,loss of fugitive gases

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Use of helicopters Noise, exhaust Combustion products Along routes Contamination levels of water,and supply vessels discharge soils and organisms, biotope

quality, behavioral patterns-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Accidental spills Oil discharge Hydrocarbons, Local (on land) Contamination level (soils, snow,(well sites, pipelines, dispersants to long-range (rivers, surface waters, ice, sediments),transport vehicles lakes and sea) vegetation and fauna, amenityand vessels) distribution values, and tourism

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Decommissioning phase

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––Technical Physical disturbance, None Locally on site Soils, permafrost stability, bottom sedi-demobilization noise ments, vegetation, fauna, behavioral patterns

––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

Produced water often has high oil content

Water brought up from wells along with theoil and gas is a major source of the hydrocar-bons released by oil exploitation. On the Nor-wegian shelf this ‘produced’ water accountedfor 76 percent of the total operational andaccidental input of hydrocarbons to the seabetween 1990 and 1995.

For offshore wells, produced water, includ-ing any added chemicals, is usually dischargedinto the sea. For several United States andNorth Sea fields, however, this water is rein-jected into the reservoir to facilitate the furtherrecovery of petroleum. Before discharge, theproduced water has to be treated to complywith regulatory limits that restrict the amountof hydrocarbons in the water. For the UnitedStates, regulations stipulate that petroleumhydrocarbons in the water should not exceed72 milligrams per liter for any one-day periodor 40 milligrams per liter as an average over30 days. Similar limits are in effect on the Nor-wegian Shelf. However, the methods used todetermine the oil concentration do not mea-sure dissolved oil components, which are thusdischarged ‘unnoticed’.

Accidental spills are rarebut can be devastating

Blow-outs, spills, and leakage during produc-tion and transport of petroleum pose the larg-est oil pollution threat to the Arctic environ-ment. In addition, fishing and other ship actionmay contribute to numerous smaller spills andleaks. Pipeline ruptures and leaks, such asthose in Usinsk, Russia in 1994, and tankeraccidents such as the Exxon Valdez in Alaskain 1989, are examples of massive oil contami-nation over large areas. The Exxon Valdezspilled 35 000 tonnes of oil, while estimates forthe Usinsk spill range from 37 000 to 44 000tonnes of crude oil flooding rivers and lakes.The Usinsk spill was in addition to chronic leak-age from the pipeline. The total discharge fromthe pipeline into the environment has beenestimated at 103 000 to 126 000 tonnes ofcrude oil. Oil blow-outs at production sites,fortunately, have not yet occurred in the Arctic.

Most oil spills are small to insignificant.For instance, the 365 accidents reported in1994 at Norwegian offshore installations to-gether released only 55 tonnes of oil, and onlyseven of the incidents discharged more thanone cubic meter. Nevertheless, it is the rare,difficult-to-predict large spills that becomeenvironmental calamities.

Based on statistics from oil spills in areasoutside the Arctic, one can make a rough esti-mate of the probability of spills over the pro-duction period of specified Arctic petroleumreserves. In the Beaufort and Chukchi Seas,such estimates predict between one and eightspills equal to or larger than 1000 barrels of

oil (approximately 160 cubic meters). The prob-ability of one or more spills is between 58 and99 percent. The number of spills exceeding10 000 barrels (1600 cubic meters) will be be-tween 0.3 and 2.5. The probability of one ormore of these large spills is between 24 and 92percent. The most likely source of these spillsis pipelines, followed by tankers and platforms.

These theoretical risk calculations do nottake special Arctic conditions into account. Inreality, pressure ridges in the ice or icebergsscouring the bottom could increase the risk fordamage to any installation on the sea floor.Arctic conditions may also affect the size ofthe spill because of difficulties in recovering oiland in drilling relief wells.

Tanker spillsare the largest threat from shipping

The main oil-related threat from shipping isconnected to transporting oil in tankers. Mostincidents occur at the terminals where tankersload or unload. Even if the discharge is consid-erable, the damage is usually localized to theimmediate area around the port.

Tanker accidents contribute a small percent-age of the overall input of oil to the oceans butget public attention because of their potentiallylarge environmental impact, particularly if thetanker is large or the spill occurs close toshore. The groundings of the Exxon Valdez offthe coast of Alaska in 1989 and the Braer nearthe Shetland Islands in 1993 are two examples.

Increased exploration and development ofoil resources in the Arctic will lead to increasedtanker traffic. A main focus will be on theNorthern Sea Route, a system of sea lanesnorth of Asia between the straits joining theBarents and Kara Seas in the west and theBering Strait in the east; see the map below.

This route has been important for transportinggoods to remote Russian settlements, andopened for international shipping in 1987.Accurate estimates of the amount of ship traf-fic in these waters are difficult to make, butthis route is by far the most active in Arcticwaters. With significant prospects for offshoreoil and gas in the Kara and Barents Seas, traf-fic along the Northern Sea Route is likely toincrease, as will the risk of accidents. An inter-national program coordinated by Russia,

149Petroleum

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Norway, and Japan is currently assessing theroute’s overall feasibility.

Other shipping, such as sealifts to isolatedcommunities and industrial facilities, traffic toand from drilling operations, icebreaker sup-port, and research cruises are also potentialsources of oil pollution. In some of the mar-ginal seas, there are large fishing fleets as well.Oil pollution from regular shipping is still aproblem in some areas, with both legal andillegal discharges of oily ballast and bilge wa-ter. There is an increasing number of touristcruises in the Arctic, with large ships carryingsubstantial amounts of bunker oil. In additionto sea ice, poor nautical charts of the Arcticincrease the risk of accidents.

Many legal instrumentsare already in place

There are a number of legal instruments toprevent oil pollution of marine waters. Someare aimed at shipping while others specificallyaddress oil and gas exploitation. The Protec-tion of the Arctic Marine Environment (PAME)component of the Arctic Environmental Pro-tection Strategy reviewed these instruments inits 1996 report. PAME has also producedguidelines for offshore oil and gas explorationand production in the Arctic and subarctic. Atpresent, getting compliance with existing legalinstruments appears more important than de-veloping new ones.

Poorly maintained pipelinespollute Russian tundra

In addition to marine shipping, large quanti-ties of oil are transported over land via pipe-lines. During the 1970s and 1980s, Russiabuilt an extensive pipeline network, includingsix trunk oil pipelines, stretching over 10 000kilometers across Western Siberia. The net-work is capable of carrying 400 million tonnes

of oil every year. As described in the introduc-tion, many of the pipelines are in poor shapeand leaks are frequent. There were 103 large-scale failures at oil and gas pipelines in theRussian Federation in 1991-93, many of themin Arctic and subarctic areas.

In the United States, the Trans-Alaska Pipe-line carries oil from the fields in Prudhoe Bayto Port Valdez on a fjord in southern Alaska.Automated shutdown of pump stations andvalves in this pipeline are designed to limitspills. At the most, about 0.2 percent of the oilin the line, or 2226 cubic meters, could spillonto the land before the line could be effective-ly shut down. A Canadian pipeline, connectingoilfields and refineries at Norman Wells on theMackenzie River with northern Alberta, hassimilar safety features.

Natural oil seepsadd to hydrocarbon load

Natural sources of hydrocarbons add to theload in the environment. For example, someoil seeps in the Arctic have been recognizedsince prehistoric times and lumps and pebblesof oil shale and seepage tar have been used asfuel by North American Inuit. In many instan-ces, the seeps have led to the discovery of com-mercially recoverable petroleum reserves. Manyof the natural oil seeps originate in north-flow-ing rivers, such as the Mackenzie and the Ob,which eventually discharge into the ArcticOcean.

Globally, oil seepage contributes between0.02 and 2 million tonnes of oil per year to theenvironment. Of the total entering the marineenvironment from different sources, at least 15percent comes from natural oil seeps. Thereare no estimates for the Arctic region, but theproportion from natural sources is probablygreater than the global average. For example,the Mackenzie River in Canada’s Arctic con-tributes the largest quantities of hydrocarbons

150Petroleum hydrocarbons

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to the Beaufort Sea region. Oil seeps have alsobeen detected in eight areas of the United StatesArctic, seven of which are located along theBeaufort Sea coast. The Barents Sea and loca-tions near Spitsbergen are other regions thathave natural oil seeps.

PAHs have many different sources

Polycyclic aromatic hydrocarbons are a groupof contaminants related to oil exploration andextraction that also have other sources. Inareas of high concentration, such as oil spills,they can be acutely toxic. The main environ-mental concern is that some of the compoundscan cause mutations and cancer at low concen-trations.

Spilled petroleum products are the largestsingle source of PAHs. Crude oils contain upto 10 percent PAHs, while the PAH content ofshale oils and coal-derived synthetics can be ashigh as 15 percent. Incomplete combustion ofwood and fossil fuels are important sources, asare incineration of garbage, steel and coke pro-duction, coal liquification, and coal gasifica-tion. Although most emissions stem from hu-man activities, there are some natural sourcessuch as microorganisms that are known toproduce small amounts of PAHs.

Produced water from both oil and gas plat-forms contains PAHs. Taking into account thelarge volumes of produced water dischargedfrom oil production, the yearly input of PAHsinto the environment, even from a single off-shore oil field, may be significant.

Natural gas contributes to climate change

Oil and gas exploration mostly have local orsubregional environmental impacts, but one ofthe pollutants, methane, is of global concern.Methane acts as a greenhouse gas and thuscontributes to global warming as discussed inthe chapter Climate change, ozone depletion,and ultraviolet radiation. It is the main compo-nent of natural gas and is released to the atmos-phere by gas drilling, from leaky pipelines, andby venting and flaring activities on oil and gasrigs. Globally, these activities are the fourthlargest source of methane to the atmosphere.

Burning of fossil fuels is also the main an-thropogenic source of the greenhouse gas car-bon dioxide.

Air, oceans, and riverscarry hydrocarbons from industrial areas

In addition to contamination from sourceswithin the Arctic, petroleum hydrocarbons aretransported from heavily industrialized areasby air currents, ocean currents, and rivers. Themain pathway is probably via the atmosphere.Based on models, it has been estimated thatatmospheric transport annually adds about40 000 tonnes of hydrocarbons to the Arctic

marine environment and about 40 000 tonnesto the terrestrial environment.

Levelsin the marine environmentDifferent analytical methods to determine totalpetroleum contamination have been used bydifferent Arctic countries, which makes it diffi-cult to compare levels in the environmentaround the circumpolar area. So far, assess-ments using comparable methods can only bemade at a subregional level.

Hydrocarbons can be detected in seawaterthroughout the Arctic. Except for local pollu-tion in harbors, the highest levels occur just offriver mouths. Concentrations in the marinewaters of the Russian Arctic are generallymuch higher than those found in North Ame-rican waters. One explanation might be differ-ences in analytical technique, but oil pollutioncarried by the large Russian rivers probablycontributes. Except for areas affected by spills,anthropogenic input so far is relatively lowand does not have any ecological significance.

Seaports are the most pollutedmarine environments

The most severe cases of pollution occur inareas with intense industrial and military activ-ity. For example, most of the sewage producedat the Murmansk Seaport and Naval Base is dis-charged untreated into the Kola Fjord. About40 ships based in this port have no oily-waterseparators or other procedures to process oil-containing waters. In winter, the Kola Fjord isrelatively stagnant, and concentrations of hy-

drocarbons sometimes exceed the maximumpermissible concentration (50 micrograms perliter) by a factor of 150 in surface waters closeto Murmansk. In summer, water circulationincreases and hydrocarbon concentrations arerarely higher than twice the permissible level.

Along the Norwegian Arctic coast, measure-ments from 1994 show that levels of hydrocar-

151Petroleum

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bons in sediment vary considerably. In general,they are higher than in other Norwegian har-bors. The highest level, 7000 milligrams perkilogram, was found in Hammerfest.

Some estuarine sedimentsare clearly contaminated

Reflecting input from north-flowing rivers, siltsediments along some coasts are contaminatedwith hydrocarbons. The highest concentrationsoccur in the estuaries of the Pechora, Ob, andYenisey Rivers. The maximum concentration inthe Pechora estuary is 250 micrograms per gram.In the Laptev Sea, outside the Lena River, thehydrocarbon concentration in the silt sedimentis even higher, over 300 micrograms per gram.

Fish levels indicatemarginal contamination of Arctic waters

Measurements of hydrocarbons in fish tissueshow that fish from the southern Beaufort Seaare more contaminated than fish from thenortheast Pacific Ocean, which is considered aclean environment. The concentrations ofhydrocarbons are similar to those in fish fromAtlantic waters. Other biota from Alaska alsoshow indications of some contamination withpetroleum hydrocarbons.

Oil spills in coastal andmarine environmentsThe impact of oil spills in the marine environ-ment depends to a large extent on whether theoil reaches sensitive animals. Large spills in theopen ocean may not have as large an impact asa small spill close to the coast or in the vicinityof large bird colonies. Transport and dispersalof oil therefore become important factors intrying to understand the risks involved in Arc-tic oil and gas exploitation. The major differ-ence between the Arctic and other areas is thepresence of ice. Lessons learned from oil spillsin other areas can therefore not be directlyapplied for the Arctic.

Ice will trap and transport oil

Normally, the lighter fraction of oil spilled atsea evaporates while the rest is dispersed in thewater with the help of wind and waves. Ice caneffectively limit this natural cleaning potential.Instead, it provides surfaces both above andbelow the water on which oil can be trapped.The undersurface of sea ice can be very rough,with large pockets in which the oil can remainfor as long as the ice stays solid. Some of theoil might even be encapsulated and move withthe ice. Oil spilled in winter under landfast icemight thus move only tens of meters from thespill area. On the outer shelf, the edge of the

multi-year pack ice can move about 150 kilo-meters per month in winter. Lack of equipmentand methods to contain oil and to clean ice-infested areas increases the potential threatfrom oil spills in the Arctic.

Shelf seas that produce and export largevolumes of ice would be particularly efficientat transporting spilled oil into the interior ofthe Arctic Ocean, where it would follow thelarge-scale drift patterns of the pack ice. Forexample, oil spilled in the Beaufort Sea maycirculate within the Beaufort Gyre for five ormore years, whereas oil spilled in the Kara andLaptev Seas could exit the Arctic via the Ba-rents Sea and Fram Strait within one or twoyears. The figure at the top of page 32 de-scribes this large-scale circulation.

Oil encapsulated in the ice will not breakdown but will instead appear essentially un-weathered at the surface when the ice starts tomelt. It is released when the ice sheet begins tobreak up. Because the dark oil absorbs heat,the break-up of oiled ice occurs about twoweeks earlier than normal. Once there is openwater, the oil slick will behave as it would inan open ocean with ice floes.

The release of oil in spring can be very dam-aging to wildlife. Biological activity is high andthe amount of open water available for birdsand marine mammals is relatively limited. Therisk of animals congregating in oily areas istherefore relatively high. This is a compellingargument for cleaning up winter oil spillsbefore spring comes.

Sunlight and microbes break down oil

Whether released at sea or on land, petroleumproducts and oily wastes will change withtime. This ‘weathering’, which is especiallywell studied in the marine environment, iscaused by a combination of physical, chemical,and biological factors.

Under temperate conditions, most of thelight hydrocarbons evaporate within one ortwo days of a spill. Computer simulationsshow that 23 percent of the mass of a hypo-thetical spill covering 150 000 square meters inthe northern Bering Sea would evaporate.After the Exxon Valdez oil spill, it was calcu-lated that 20 percent of the oil evaporated.Once the hydrocarbons are in the air, light andoxygen will break them down in photochemi-cal reactions. Low-molecular weight com-pounds therefore last only a few days. Highermolecular weight compounds appear to have ahalf-life of about a week. In the High Arctic,however, and especially in ice-infested waters,evaporation will generally be slower.

In ice-covered waters, evaporative loss alsodepends on the timing of the spill. If it occursduring the initials stages of ice growth, dis-solved hydrocarbons may sink toward the bot-tom with the brine that forms during ice for-mation. Here they would persist for several

152Petroleum hydrocarbons

months without evaporating. When oil-pol-luted ice breaks up, waves can very rapidly dis-solve the hydrocarbons in the water, increasingconcentrations by factors of 300 to 700 in lessthan one day. The concentrations would grad-ually decrease over the next six days as thecompounds evaporate.

Bacteria and fungi can use hydrocarbons asan energy source and thus help in the finalclean-up of an oil spill. However, in the Arctic,the degradation will be slow due to the shortseason in which temperatures are high enoughfor bacteria and fungi to be active. In BeaufortSea sediment, oil degradation was apparentonly after eight months, even though the bac-terial community could grow at temperaturesbelow freezing. The slow rate of biodegrada-tion, which has also been demonstrated in theBarents Sea, may have been due to a lack ofnutrients. Another reason may have been thatthe physical and chemical characteristics of oilin cold water make it less available for themicrobes. In contrast to temperate spills, nat-ural cleaning after a spill in the Arctic maytherefore take decades rather than years. Thisunderscores the need for special care to protectsensitive areas against spills.

Effects on animals vary

Oil spills will affect most exposed animals, butthe impact will vary greatly depending onspecies and circumstance. Although zooplank-ton take up components of the oil, the toxiceffects appear to be short-lived. For example,the Potomac spill off West Greenland revealedoil in the gut of copepods and amphipods butfound no apparent effects.

Fish eggs and larvae are vulnerable. Theyoften develop near the surface, where they aremore likely to be exposed to dissolved oil com-ponents. They are also more sensitive to oiltoxicity than adult fish.

Adult fish in the Arctic are probably nomore sensitive to oil spills than fish in otherareas, and the experience so far has been thateven large oil spills have had no apparentimpact. However, natural variations in fishstocks would make it difficult to prove thatany effects were caused by the oil. Fish, in gen-eral, are able to detect oil even at extremelylow concentrations, and may avoid oil spills byswimming away.

Soiled feathers kill seabirds

Soiled seabirds have become symbols of theenvironmental threat posed by oil spills. Oilfouls their plumage, taking away their insula-tion, so they quickly lose heat. The birds alsoingest oil when trying to clean their feathers.The oil toxins may impair their ability toreproduce, and soiling of eggs kills embryos.

Seabirds are particularly at risk becausehuge populations gather in one place. A single

Arctic breeding colony may contain a largeproportion of the individuals of a certainspecies, and one spill in the vicinity of such acommunity could severely harm the world-wide population. The long-term effect of oilspills on bird populations is controversial, andit is uncertain whether observed oil mortalitiesare substantial in relation to natural mortality.

The damage a spill does to bird populationsis related less to its size than to its proximity intime and space to large bird gatherings. Whenthe Amoco Cadiz released 250 000 tonnes ofoil off the coast of Brittany, France, only about4500 birds were killed, whereas 35 000 tonnesof oil from the Exxon Valdez probably killed500 000 birds. Also, a nearly inconspicuousspill in 1979 on the east coast of Finnmark,northern Norway, killed between 10 000 and20 000 birds, primarily guillemots.

Behavioral patterns make some seabirdsmore sensitive than others to oil spills. Alcidsare among the most sensitive, in particularAtlantic puffins, common murres, thick-billedmurres, razor-billed auks, and northern gan-nets. Common eiders are also considered vul-nerable.

Some sea mammals are vulnerable to oil-soiling of their fur

Fur seals, sea otters, and polar bears rely ontheir fur for insulation and also to help themkeep afloat. Oil contamination may thereforebe particularly damaging to these animals.In the Exxon Valdez spill, approximately 2000to 3000 sea otters in the area were killed di-rectly after the accident and a number prob-ably died later.

Seals and walrus do not rely on their fur forinsulation, but may still suffer if oil hindersthem when they swim. In these conditions,pups may die from exhaustion. Oil is alsoknown to cause eye lesions.

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Whales seem unharmed by contact with oil.One reason might be that oil does not stick totheir skin. They may also avoid oil slicks, butseveral observations suggest that they do nottake any notice of them.

Rocky shores recover fairly fast

Shoreline and shallow subtidal communitiesare the prime focus of concern during mostcoastal spills. The impact can vary greatly,however, depending to a large extent onwhether the physical characteristics of thecoast allow waves to wash the oil away, or ifsediments retain the contamination for a longtime. Several attempts have been made to clas-sify sensitivity. The most sensitive areas areestuarine salt marshes where oil can remainfor a decade. Straight, rocky headlands, on theother hand, might be clean after less than oneyear. Some sensitivity indexes also take biolo-gical and human use of the seashore intoaccount.

A thorough investigation of the immediateimpact of the Exxon Valdez spill showed thatmembers of the four main groups of organisms– sea weed, barnacles, mussels, and periwin-kles – survived the spill. A year late, densitieswere somewhat less than on other shores, butafter two years most oiled shorelines appearedhealthy and in a state typical of pre-spill com-munities.

Many organisms, such as barnacles andmussels, close up to avoid drying during lowtide, and this behavior may also protect themfrom light oil contamination. Mobile organ-isms such as crustaceans may escape by seek-ing deeper water. However, this escape response

may cause the animals to get stuck in the oiland, in general, crustaceans and amphipodsare sensitive to oil spills. After the AmocoCadiz spill, it took eight years for the amphi-pod populations along some of Britanny’sshores to return to normal. Scavenging amphi-pods play a key role in Arctic marine foodwebs and oil damage may therefore have moresevere consequences in the Arctic than inwarmer regions.

Macroalgae growing just below the shore-line on rocky shores may be protected by theirmucoid surface. However, after a spill of 1000tonnes of bunker oil off the Arctic coast ofNorway in 1981, all macroalgae died in theheavily oiled areas. In lightly oiled areas, theparts of the macroalgae that had been coatedwith oil showed retarded growth the nextspring, but new sprouts appeared healthy.

Sand and mudretain oil and increase biological damage

On sheltered sandy and muddy shores, theeffects of oil spills can be pronounced andremain for many years. Two years after anupper-shore spill of diesel oil at Spitsbergen,substantial amounts of oil were still presentone half meter down in the shore sediment. Inthis case, the only species that was presentbefore the spill disappeared. Experiences fromexperimental and non-Arctic spills vary fromno apparent long-term effects to severe im-pacts with instability in the structure of thebiological community up to a decade after theaccident. Generally, recovery is probably slow-er in the Arctic because of slow turn-over ratesand long life spans of the organisms.

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The underside of sea icemay be a vulnerable environment

A unique feature of the Arctic marine environ-ment is the community of plants and animalsthat live on the underside of the sea ice. Anyoil spilled under multi-year ice will remain un-changed until the ice thaws, and plants andanimals here will thus be exposed to toxic sub-stances for a long time. Some experimentalstudies indicate that algae density, biomass,and productivity did not change when a mod-erate amount of oil was applied under ice.Also, the effects on an ice amphipod were onlymoderate. However, amphipods are known tobe sensitive to oil and to get caught easily in oilfilm, so spills under ice are likely to trap andsmother a substantial number of these animals.

Oil in terrestrial andfreshwater environmentsData on hydrocarbons in soil are only avail-able for Russia, where levels away fromknown spills range from 10 to 40 microgramsper gram. Spills and leaks from pipelines makelocal levels much higher. For example, afterspills from the Vosey Pipeline, as much as 15percent of the dry weight of soil in a spot closeto a pipeline leak was hydrocarbons.

Long-term monitoring of petroleum hydro-carbons in Russian river water indicates highpollution levels in the areas of oil and gasexploration and production. This is especiallytrue in the lower part of the Ob River, wherehydrocarbon concentrations often reach sev-eral milligrams per liter. Even if local contami-nation is severe, however, these rivers have aself-purification ability that keeps hydrocar-bons from being transported downstream bythe flow of the river. For example, during theKomi oil spill, only a minor portion of thespilled oil reached the mouth of the PechoraRiver, though some tar balls were trappedthere and ‘fingerprint’ analysis proved thatthey originated from the spill area.

The highest values reported for North Ame-rican river sediments are lower than those inthe Russian rivers. Values of about 35 micro-grams per gram were found close to the Beau-fort Sea coast, and the highest values – up to148 micrograms per gram – are from NormanWells, an active oil exploitation area along theMackenzie River.

Soils, plants, and snowdetermine how oil spreads on land

Oil spills on land will, in general, be more con-fined than spills in water. The rate and extentof spreading will depend on plant cover, whetherthe ground slopes, and how much oil the soiland vegetation will absorb. Mosses, for exam-

ple, are very efficient in absorbing oil. Waterlog-ged soils also hinder oil penetration. Cracks inthe soil above permafrost, on the other hand,may lead oil down to the permafrost where itcan spread horizontally into deeper soil layers.

Snow also affects spreading patterns. Hotoil, such as from a ruptured pipeline, tends toform channels in the snow, transporting the oilalong the underlying ground and contaminat-ing relatively large areas.

One terrestrial spill has been well docu-mented. In August 1989, about 50 cubic me-ters of oil and produced water leaked from avalve in a production pipeline near PrudhoeBay. The oil spread over half a hectare of Arc-tic coastal tundra, inundating small lakes andponds. Most of the oil stayed close to the sur-face of the water-saturated tundra. Within ayear, the concentration of oil in the soil haddecreased almost 80 percent, but, after this ini-tial drop, natural clean-up by light and bacte-ria slowed down considerably. By 1991, thawsettlement of the permafrost had stabilized andplant cover was well on its way to meeting theregulatory criterion for recovery, equal to 30percent of the mean percentage plant cover inan adjacent unaffected area.

Oil will destroy plant cover

The amount of damage oil spills cause on landvaries, but all actively growing plant tissues inwetlands can be completely destroyed. Sedgesare known to recover, while mosses can becompletely eliminated. If the damage is limitedto above-ground parts of the plants, the vege-tation can usually recover. Damage to theroots, however, will have effects even in thefollowing growing season. Plants with shallowroots are probably the most sensitive.

Plant damage can have more severe conse-quences in the Arctic than in other areas. Arc-tic plant cover is usually extremely vulnerableto surface damage because it is so thin. It alsotakes longer to grow back because of low tem-peratures and the lack of nutrients. After a spill,the toxic components of oil are expected to re-main in the soil for up to 30 years, further de-creasing the chance that vegetation will recover.

Studies after an oil spill along the Trans-Alaska pipeline have shown that it is possibleto assist vegetation recovery by applying fertil-izer and by tilling the soil.

The effects of oil on terrestrial animals arepoorly understood, but animals that rely ontheir fur for insulation might suffer. For exam-ple, a major spill along the St. Lawrence Riverkilled a number of muskrats.

Russian wetlandsare polluted from production activities

In Russia, oil and gas extraction poses a seri-ous threat to wetlands in the production areaswhen oil and other contaminants are discharged

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directly into landscape depressions. In north-western Siberia, petroleum concentrations inthis discharge can range from 0.5 to 5.2 gramsper liter. The depressions are also used fordumping untreated waste water. When wet-lands overflow, they serve as secondary sourcesof hydrocarbons and other chemicals to near-by rivers and lakes, and almost all samplestaken from rivers in northwest Siberia exceedthe maximum permissible concentrations.

Spills in streams and lakescan taint the fish

If oil gets into streams, ponds, or lakes, it cankill zooplankton, and the remaining oil canprevent recovery for several years. In streamswith prolonged seepage, total abundance andspecies diversity is known to decrease.

Plants in freshwater ecosystems recover fair-ly quickly, especially in streams where most ofthe oil gets washed away.

Experiences from areas outside the Arcticshow that oil can kill fish, but so far there areno documented cases of this in the Arctic.Tainting of fish, on the other hand, has beenan issue. For example, after a spill of diesel oilinto a river, people living downstream com-plained that the fish tasted oily, and laboratorystudies showed that the spilled fuel could havebeen the cause.

Birds that gather by lakes and ponds in theArctic will be sensitive to oil spills. For exam-ple, a large number of ducks, geese, and he-rons were killed after a spill on the St. Law-rence River. After the Exxon Valdez spill,numerous bald eagles nesting in the area diedafter eating dead, oil-contaminated birds andsea otters.

Levels and effects of PAHsPolycyclic aromatic hydrocarbons do not dis-solve well in water and instead tend to associ-ate with particles. Sediments are thus the mostimportant reservoir in the environment. Incities, PAHs are major components of air pol-lution. This is especially true in cities on theKola Peninsula, where PAH levels regularlyexceed maximum allowable concentrations.

PAHs are degraded by light, either in theatmosphere or in the upper reaches of a watercolumn. In the Arctic, degradation is generallyslower than at lower latitudes because of lowtemperatures and low light.

Seawater and sedimentsare clearly contaminated with PAHs

Several areas of the Arctic have elevated levelsof PAHs in seawater and marine sedimentsrelative to global background concentrations.The Beaufort Sea is an area with particularlyhigh levels. The main source is probably the

Mackenzie River, which flows through regionswith known fossil fuel deposits, natural hydro-carbon seepage, and burned-over areas. In fivelocal areas within the Arctic, sediment concen-trations exceed environmental guideline limits.These are in the Barents Sea, Spitsbergen, har-bors in northern Norway, the Beaufort Sea,and Tuktoyaktuk Harbour in the NorthwestTerritories, Canada.

The relationship between different PAHcompounds can be used to identify their mainsources. Alaskan sediments point to petroleumhydrocarbons, while PAHs in the Barents Seashow a greater contribution from combustionsources. The Canadian Beaufort Sea has a mix-ture of the two sources, which is also the casefor Russia’s marine environment, though theRussian levels are generally lower. Sedimentsnear Spitsbergen are enriched in PAHs com-pared with the Russian sediments, which prob-ably reflects contamination from coal particlesand petroleum products.

Fish can bioaccumulate PAHs directly fromsediment. In general, PAH levels in Arctic ma-rine animals are similar to those reported forbackground locations outside the Arctic. How-ever, starry flounder from Tuktoyaktuk Har-bour had consistently high concentrations,which probably reflects a chronic exposurefrom polluted water and sediment in theharbor.

Fish are able to break down PAHs, andthese compounds do not seem to bioconcen-trate or magnify in the food web.

Freshwater and terrestrial PAH levelsare also high

The levels of PAHs in freshwater sedimentsvary greatly, and probably reflect a combina-tion of long-range transport and local indus-trial and natural sources in the watershed. Aswith the marine environment, several areashave higher concentrations than the global

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Levels of benzo[a]pyrene in the air of Russian cities onthe Kola Peninsula; mean (annual average) and maxi-mum (highest concentration during the year over a 20minute period) levels in 1991 and 1993, in nanogramsper cubic meter. The maximum permissible concentra-tion is 1 nanogram per cubic meter.–––––––––––––––––––––––––––––––––––––––––––––––––

City/Town Value 1991 1993–––––––––––––––––––––––––––––––––––––––––––––––––

Apatity Mean 0.5 –Maximum 1.4 2.7

Kandalaksha Mean 2.2 –Maximum 5.8 9.5

Kovdor Mean 0.8 –Maximum 2.5 1.8

Monchegorsk Mean 2.2 –Maximum 8.6 8.1

Murmansk Mean 1.1 –Maximum 4.0 3.4

Nikel Mean 0.5Maximum 2.9 2.2

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background. Norwegian peak values reachalmost 7000 nanograms per gram of sediment.

Concentrations measured in burbot fromCanada, Russia, and Finland are probablybelow those that would cause observableeffects. The highest values are reported for fishcaught at Norman Wells in the NorthwestTerritories, Canada.

In Arctic Russia, only a few analyses ofwhitefish from major rivers are available. Theyshow that there must be a chronic source of hy-drocarbons at most of the sampled locations.

Reindeer and Arctic birds in Russia haverelatively low PAH concentrations, whilePAHs levels in bird carcasses from Alaska arehigher.

SummaryThe major anthropogenic source of hydrocar-bon contamination in the Arctic is oil and gasdevelopment, but several other sources con-tribute to the load in the environment. Theseare releases from marine shipping, burning offossil fuels, long-range transport, and naturaloil seeps.

Accidental oil spills and chronic releasesfrom poorly maintained pipelines and fromships pose the greatest threat from petroleumhydrocarbons. Some severe local and regionalproblems associated with oil and gas explo-ration, development, and transportation havealready occurred.

The Arctic environment is more vulnerableto spills than warmer environments because oil

breaks down more slowly under cold, darkconditions and because Arctic plants and ani-mals need a longer time to recover from dam-age. In addition, remedial measures are diffi-cult due to the extreme conditions of cold, icecover, and winter darkness.

The environmental threats to the Arcticassociated with oil and gas development, pro-duction, and transport are primarily localand/or regional and not circumpolar in scale.An important exception is if a large oil spillwere to occur coincidentally with large congre-gations of certain migratory bird and mammalspecies in Arctic areas. In such cases, a largeproportion of a population may suffer.

Petroleum hydrocarbons are also present inareas not directly affected by spills or pro-longed chronic releases. However, in back-ground circumpolar environments, concentra-tions are relatively low and not of ecologicalsignificance. The most highly contaminatedareas in the Arctic are certain rivers and estu-aries in Russia close to human settlements andindustrial or military areas, and in terrestrial/freshwater environments where accidental andoperational spills have occurred, such as thearea affected by the Usinsk pipeline rupture.

Polycyclic aromatic hydrocarbons (PAHs)are widespread in the Arctic environment.They come from a variety of sources, includingoil, combustion, and biological activity. Mea-sured levels in the environment are generallybelow the levels thought to cause observableeffects in biota, although certain PAHs doreach levels of concern in marine sediments inlimited areas.

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