State of Knowledge Review of Fate and Effect of Oil

in the Arctic Marine Environment

2011

A report prepared for the National Energy Board of Canada

by

K. Lee1, M. Boudreau2, J. Bugden1, L. Burridge3, S.E. Cobanli1, S. Courtenay2, S. Grenon4, B. Hollebone5, P. Kepkay1, Z. Li1, M. Lyons2, H. Niu1, T.L. King1,

S. MacDonald5, E.C. McIntyre1, B. Robinson1, S.A. Ryan1 and G. Wohlgeschaffen1

1Centre for Offshore Oil, Gas and Energy Research (COOGER), Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia, Canada, B2Y 4A2 2Fisheries and Oceans Canada, Gulf Fisheries Centre, P.O. Box 5030, Moncton, New Brunswick, E1C 9B6 3Fisheries and Oceans Canada, St. Andrews Biological Station, 531 Brandy Cove Road, St. Andrews, New Brunswick, Canada, E5B 2L9 4Triox Environmental Emergencies, 4839 Garnier, Montral, Qubec, Canada, H2J 3S8 5Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada, K1A 0H3

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TABLE OF CONTENTS List of Figures ................................................................................................................................ iv List of Tables .................................................................................................................................. v List of Acronyms ........................................................................................................................... vi Executive Summary ........................................................................................................................ 1 1. Introduction................................................................................................................................. 4 1. Introduction................................................................................................................................. 4 2. Characterization and Classification of Crude Oil ....................................................................... 9

2.1 Physical and Chemical Properties......................................................................................... 9 2.2 Significance of Oil Properties in Oil Spill Response.......................................................... 12 2.3 Canadian Arctic Offshore Crude Oils................................................................................. 13

3. Oil Spills in Arctic Waters........................................................................................................ 17 3.1 International Concerns and Governance............................................................................. 17 3.2 Behaviour and Fate of Oil................................................................................................... 18

Oil in Ice-Free Waters .......................................................................................................... 19 Oil in Ice Covered Waters..................................................................................................... 22

3.3 Factors Influencing Oil Behaviour...................................................................................... 24 Spreading in Broken Ice........................................................................................................ 24 Movement on Ice ................................................................................................................... 27 Movement Under Ice............................................................................................................. 27 Movement Through Ice ......................................................................................................... 29 Adsorption to Snow ............................................................................................................... 31

3.4 Factors Influencing Oil Fate (Weathering) ......................................................................... 32 Evaporation........................................................................................................................... 32 Dissolution ............................................................................................................................ 33 Dispersion ............................................................................................................................. 34 Emulsification ....................................................................................................................... 35 Photo-Oxidation.................................................................................................................... 38 Biodegradation ..................................................................................................................... 39 Formation of Oil-Mineral Aggregates.................................................................................. 44 Sedimentation........................................................................................................................ 46

4. Oil Spills in Canada from Offshore Oil and Gas Activities...................................................... 47 4.1 Oil Types from Vessel Operations...................................................................................... 50 4.2 Oil Types from Oil Platform Operations ............................................................................ 51

Crude Oil from Drilling Activities ........................................................................................ 52 Petroleum Products used in Operations ............................................................................... 52

4.3 Overview of Oil Spill Risks in the Canadian Arctic........................................................... 52 Defining Risk......................................................................................................................... 52 Incidents from Vessel Operation........................................................................................... 54 Incidents from Oil Platform Operations ............................................................................... 57

4.4 Modelling Spill Scenarios and Oil Behaviour .................................................................... 62 Scenario for Spills of Crude Oil............................................................................................ 63 Scenario for Spills of Intermediate Fuel Oil......................................................................... 66 Scenario for Spills of Marine Gasoil .................................................................................... 67 Scenario for Spills of Aviation Fuel (Jet Fuel) ..................................................................... 69

Recommendations from Modelling Exercises ....................................................................... 70 5. Offshore Arctic Oil Spill Response Options............................................................................. 72

5.1 Development of Policies, Regulations and Capacity.......................................................... 72 5.2 Mechanical Containment and Recovery ............................................................................. 74 5.3 In situ Burning .................................................................................................................... 76 5.4 Chemical Dispersion........................................................................................................... 79 5.5 Oil-Mineral Aggregates ...................................................................................................... 82 5.6 Bioremediation.................................................................................................................... 85 5.7 Natural Attenuation............................................................................................................. 89

6. Biological Effects of Oil ........................................................................................................... 91 6.1 Oil Toxicity in the Arctic.................................................................................................... 91 6.2 Routes of Exposure ............................................................................................................. 93 6.3 Bioaccumulation, Biomonitoring and Toxicity Assessment .............................................. 95 6.4 The Arctic Food Web.......................................................................................................... 98 6.5 Effects on Arctic Sea Ice Communities ............................................................................ 100 6.6 Effects of Oil on Arctic Biota ........................................................................................... 103

Bacteria............................................................................................................................... 103 Phytoplankton and Macroalgae.......................................................................................... 104 Salt Marsh Vegetation......................................................................................................... 107 Zooplankton ........................................................................................................................ 108 Fish ..................................................................................................................................... 112 Benthic Invertebrates .......................................................................................................... 126 Mammals............................................................................................................................. 137

7. Arctic Oil Spill Field Trials .................................................................................................... 150 7.1 Balaena Bay experiment 1974 - 1975 (Norcor)................................................................ 150

Balaena Bay Revisited: 1981 .............................................................................................. 152 7.2 Baffin Island Oil Spill Experiment (BIOS) ...................................................................... 154

Nearshore Study.................................................................................................................. 155 Shoreline Study ................................................................................................................... 158 BIOS Revisited .................................................................................................................... 160

7.3 Field Trials in Svalbard, Norway...................................................................................... 162 Early Field Studies on Oil Bioremediation......................................................................... 162 In Situ Treatment of Oiled Sediment Shorelines (ITOSS) Program ................................... 162

7.4 Field Trial Projects on Arctic Oil Spills in Ice ................................................................. 165 7.5 Field Trials on Enhanced Oil Dispersion with Mineral Fines .......................................... 169 7.6 Monitoring Arctic Offshore Oil and Gas Operations ....................................................... 169 7.7 Future Oil Spill Field Trials in the Arctic......................................................................... 170

8. Operational Waste Discharges................................................................................................ 174 8.1 Produced Water................................................................................................................. 174

Chemical Composition........................................................................................................ 175 Petroleum Hydrocarbons.................................................................................................... 176 Environmental Concerns over Discharges ......................................................................... 177 Fate following Discharge into the Ocean ........................................................................... 179 Environmental Effects of Discharges.................................................................................. 179 Effects on Water-Column Organisms ................................................................................. 180 Accumulation and Effects in Sediments .............................................................................. 180

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Aquatic Toxicity .................................................................................................................. 181 Bioaccumulation and Biomarkers as Evidence of Exposure .............................................. 183 Alteration of Trophic Level Dynamics by Produced Water................................................ 186 Ecological Risk of Produced Water Discharges................................................................. 187 Produced Water Treatment................................................................................................. 188 Environmental Effects Monitoring and Research Needs .................................................... 189

8.2 Drilling Muds.................................................................................................................... 191 Arctic Marine Food Webs and Toxicity .............................................................................. 193

9. Case Study: The Exxon Valdez Oil Spill................................................................................. 195 9.1 Fate of the Oil ................................................................................................................... 197 9.2 Effects of the Oil............................................................................................................... 200

Bioavailability..................................................................................................................... 200 Shoreline Flora and Fauna................................................................................................. 200 Invertebrates ....................................................................................................................... 202 Fish ..................................................................................................................................... 202 Birds .................................................................................................................................... 203 Marine Mammals ................................................................................................................ 204

9.3 Present Status of Injured Resources and Services ............................................................ 205 9.4 Lessons Learned and Issues to Consider .......................................................................... 208

10. Future Research Needs ......................................................................................................... 209 10.1 Oil Detection................................................................................................................... 209 10.2 Oil Fate and Behaviour ................................................................................................... 209 10.3 Biological Effects............................................................................................................ 210 10.4 Mechanical Recovery................................................................................................. 210 10.5 In Situ Burning................................................................................................................ 211 10.6 Enhanced Dispersion ...................................................................................................... 211 10.7 Biodegradation and Natural Attenuation ........................................................................ 211 10.8 Development of Predictive Models ................................................................................ 212 10.9 Field Trials ...................................................................................................................... 212

11. Acknowledgements............................................................................................................... 213 References................................................................................................................................... 214 Appendix 1.................................................................................................................................. 257

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List of Figures Figure 1 Since 1980 industry has increased the recovery of oil from the offshore sector to meet

global demand as land-based oil reserves declined. There is a greater risk of spills and damage as operations expand into the frontier regions including the deep waters off the continental shelf and the Arctic (Sandrea and Sandrea, 2007). .............................................. 4

Figure 2 The significance of the oil and gas industry to Canadas GDP in 2006........................... 5 Figure 3 Norman Wells crude oil dynamic viscosity as a function of temperature; data from

Environment Canadas Oil Properties database (Environment Canada, 2001a). ................. 11 Figure 4 Physical, chemical and biological processes affecting the fate and behaviour of spilled

oil (ITOPFL, 2002). .............................................................................................................. 20 Figure 5 Oil and ice interaction processes (Bobra and Fingas, 1986). ......................................... 23 Figure 6 Canadian Arctic (source: Solar Navigator, 2011, http://www.solarnavigator.net). ....... 47 Figure 7 Exploration parcels of Cairn Energy in the Greenland offshore (Cairn, 2011).............. 49 Figure 8 Accidents by ship type; OBO = other bulk operations (source: Transportation Safety

Board of Canada). ................................................................................................................. 54 Figure 9 Types of accidents (Source: Transportation Safety Board of Canada). ......................... 55 Figure 10 Canadian Arctic shipping routes. ................................................................................. 56 Figure 11 Number of spills per year in Nova Scotia from offshore operations............................ 58 Figure 12 Number of spills per year in Newfoundland-Labrador from offshore operations........ 58 Figure 13 Total spill volume in litres per year off Nova Scotia. .................................................. 59 Figure 14 Total spill volume in litres per year off Newfoundland. .............................................. 60 Figure 15 Oil budget for a spill of 4000 m3 of Amauligak crude oil as calculated by ADIOS2. . 64 Figure 16 Predicted change in viscosity for Amauligak crude oil as calculated by ADIOS2. ..... 65 Figure 17 Predicted change in density for Amauligak crude oil as calculated by ADIOS........... 65 Figure 18 Oil budget for a spill of 1000 m3 of IFO 180 as calculated by ADIOS2. .................... 66 Figure 19 Predicted change in viscosity for IFO 180 as calculated by ADIOS2. ........................ 67 Figure 20 Oil budget for a spill of 100 m3 of MGO as calculated by ADIOS2............................ 68 Figure 21 Oil budget for a spill of 10 m3 of jet fuel as calculated by ADIOS2............................ 69 Figure 22 The Arctic Food Web (ACIA, 2004)............................................................................ 98 Figure 23 Energy flow above trophic level 1 from phytoplankton and pelagic detritus in red, or

benthic detritus in blue, and proportional shades in between. Top panel: eastern Bering Sea shelf; bottom panel: western Bering Sea shelf. Box and text size are proportional to log10 of biomass for the compartment; area of each link proportional to volume of flow (Aydin et al., 2002). .............................................................................................................................. 99

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List of Tables Table 1 Canadian Arctic oils (Drummond, 2006). ...................................................................... 15 Table 2 Vessel types operating in Arctic waters and oil types carried onboard. .......................... 50 Table 3 Reported vessel accidents in the Canadian Arctic. .......................................................... 57 Table 4 Historical large oil spills in barrels (bbl) from offshore well blowouts (source: Oil Spill

Intelligence Report database)................................................................................................ 61 Table 5 Valued ecosystem components (VEC) of various Arctic regions at risk from oil spills

(INAC, 2010; Word and Perkins, 2011). .............................................................................. 92 Table 6 Food web functional group and acute toxicity LC50 (95% confidence interval) using 2-

methyl naphthalene for co-inhabiting Arctic species (Camus et al., 2010; Carroll et al., 2010). .................................................................................................................................... 96

Table 7 Experimental crude oil spills of a few barrels to hundreds of barrels conducted in sea ice, regardless of latitude (Dickins, 2011)................................................................................. 166

Table 8 Spreading comparison for a 1600 m3 (10,000 bbl) crude oil spill (SL Ross Environmental Research Ltd. et al., 2010). ........................................................................ 167

Table 9 Concentration ranges (mg/L or parts per million) of several classes of naturally-occurring metals and organic chemicals in produced water world-wide (Neff, 2002)....... 176

Table 10 National permissible concentrations of total oil and grease in produced water destined for ocean disposal (Veil, 2006)........................................................................................... 188

Table 11 Summary of produced water treatment systems used by three Arctic oil and gas installations; adapted from Hawboldt et al. (2010)............................................................. 189

Table 12 Status in 2010 of resources and services injured by the Exxon Valdez oil spill in 1989. Human services are those which were negatively impacted because of their connection with impacted resources (EVOS Trustee Council, 2010). .......................................................... 207

Table 13 Sources of peer-reviewed biological effects data from Camus et al. (Camus et al., 2008) with additional references added. ....................................................................................... 257

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List of Acronyms AhR aryl hydrocarbon receptor AL Arabian light, crude oil ANS Alaska North Slope, crude oil API American Petroleum Institute BaP benzo[a]pyrene BIOS Baffin Island Oil Spill Project BTEX benzenes, toluenes, ethylbenzenes, xylenes CCG Canadian Coast Guard CEWAF chemically enhanced water accommodated fraction CNLOPB Canada-Newfoundland and Labrador Offshore Petroleum Board CNSOPB Canada-Nova Scotia Offshore Petroleum Board

CYP1A cytochrome P4501A, an enzyme system used as a biomarker for detecting biological effects of xenobiotics DE dispersant effectiveness DGGE denaturing gradient gel electrophoresis DOR dispersant-to-oil ratio dpm disintegrations per minute (a measure of radioactivity) DWH BP Macondo MC 252 Deepwater Horizon spill in the Gulf of Mexico, April 2010 EROD ethoxyresorufin-O-deethylase EVCO Exxon Valdez crude oil; the oil specifically from this spill EVOS Exxon Valdez oil spill GC/MS gas chromatography-mass spectrometry GST glutathione S-transferase IFO intermediate fuel oil IMO International Maritime Organization ISB in situ burning ITOSS In situ Treatment of Oiled Sediment Shorelines JIP Joint Industry Program

LC50 lethal concentration 50: the concentration of a toxicant that kills 50% of the test organisms in an acute toxicity test

MESA medium South American, crude oil MGO marine gasoil or marine diesel OBM oil-based mud OMA oil-mineral aggregates PAH polycyclic aromatic hydrocarbon PEC predicted environmental concentration PNEC predicted no effect concentration ppt parts per thousand; often used as units of salinity PWS Prince William Sound ROS reactive oxygen species

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SBM synthetic-based mud SPM suspended particulate matter TOSC total oxyradical scavenging capacity TPAH total polycyclic aromatic hydrocarbons TPH total petroleum hydrocarbons UV ultraviolet light (10 nm to 400 nm) VEC valued ecosystem component WAF water accommodated fraction WBM water-based drilling muds

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1

Executive Summary

The improvement of policies and regulations for spill response/remediation technologies, and

contingency plans for marine environmental protection to address the anticipated growth of

Canadas offshore petroleum industry in the North will require the best available information on

the factors and processes influencing the fate and effects of oil released into the marine

environment. As the result of past interests in the development of oil and gas resources in the

Canadian Arctic, as well as studies by other northern countries, a vast amount of basic

information exists to fulfill our need for science based advice to support environmental risk

assessments. However, this review of emerging environmental concerns has also identified a

number of knowledge gaps that should be addressed to ensure the protection of our marine

habitat and its living resources within the Arctic.

The risk of having an oil spill in Canadian Arctic waters is anticipated to increase because of

community growth that will increase marine traffic and industrial development including

offshore oil exploration and production. A range of petroleum hydrocarbon fluids from crude

oils to refined products will be transported within the Arctic. Of these, crude oil will likely be

the largest source of petroleum hydrocarbons transported. While the quantities of a spill from a

tanker may be large, the probability of a spill occurring is low based on the current information

available from historical records. Nevertheless, response measures must be considered within

contingency plans for a worst-case challenging situation such as a deep-well blowout in the

Arctic in the presence of ice.

A combination of laboratory, mesocosm and field studies have shown that the physico-chemical

properties of oil, temperature and the presence or absence of ice will influence the fate and

behaviour of oil spilled in the environment as well as the effectiveness of spill response

operations. For example, due to reduced rates of evaporative loss under cold temperature

conditions, oil will retain its viscosity and remain more persistent in Arctic waters. On the other

hand, there can also be some advantages to consider when oil is spilled in ice infected waters.

The decrease in oil evaporation may retain an oils flash point and viscosity providing an ideal

environment for in situ burning (ISB). The results of recent field tests have also demonstrated

that the inhibition of oil-weathering processes (natural, physical and chemical processes that

oil undergoes following its release into the environment) in ice and cold temperatures prolonged

the window of opportunity for the application of chemical oil dispersants as a spill response

strategy. In addition to active oil spill response strategies, there is also a renewed interest in the

potential rates of natural recovery in the Arctic following oil spill events. This is largely due to

advances in the application of biotechnology techniques in microbial ecology that have

highlighted the significance of natural oil biodegradation rates by indigenous bacteria and the

influence of suspended particulate material on the dispersion and biodegradation rates of residual

oil.

In terms of the development of predictive models on the fate, behaviour and effects of oil on

various components of the Arctic ecosystem, while there is a considerable amount of existing

data, the results from experimental studies are largely anecdotal or empirical in nature. As a

result, there is limited data of use for the development of integrated risk assessment models that

fully take into account the numerous physical, chemical and biological processes within the

Arctic ecosystem.

A multitude of biological effects have been observed in toxicological studies with oil with a

range of biota covering multiple trophic levels. In the Arctic, seasonal aggregations of animals,

such as marine mammals in open areas of sea ice, seabirds at breeding colonies or feeding sites,

or fish at spawning time may be particularly vulnerable to oil spills. For example, an oil spill in

the spawning areas of polar cod could severely reduce a year-class of the population. Appendix

1, Table 13, provides peer-reviewed biological effects data from an extensive review by Camus

et al. (2008), to which additional references have been added. There has been a shift in

biological effect studies from acute studies focused on mortality as the end-point to that of

chronic responses associated with much lower exposure levels and their effect on the long-term

health, growth and reproduction of the target organisms. With the implementation of ecosystem

based management by regulators, future studies must include consideration of biological effects

on population, and on community structure and function.

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Interpretation of the data collected for environmental risk assessments is challenging as the

exposure conditions in past scientific studies (e.g. dosage and exposure time) are frequently

outside of the range observed in the field following actual spill events. Furthermore, as illustrated

by a case study following the Exxon Valdez spill in Prince William Sound, Alaska, a consensus

on the levels of environmental impacts have not been achieved due to a number of confounding

factors including different approaches to natural resource damage assessment, the lack of pre-

spill baseline information, and reported high levels of natural variation in population numbers

and community structure.

To address the knowledge gaps identified in this review, additional scientific research in

Canadian Arctic waters, including the conduct of large-scale field trials, should be conducted on:

1) the behaviour, transport and fate of oil spilled in the Canadian Arctic; methodologies to

monitor acute and chronic biological effects and recovery on multi-trophic level valued

ecosystem components; and 3) the development, application and validation of oil spill

countermeasures including natural recovery (natural attenuation). To optimize the use of

scientific expertise and resources, the reseach program would contribute towards an international

pan-Arctic global effort involving both government and non-governmental organizations

including academia and the private sector.

Suggested Citation:

Lee, K., M. Boudreau, J. Bugden, L. Burridge, S.E. Cobanli, S. Courtenay, S. Grenon, B. Hollebone, P. Kepkay, Z. Li, M. Lyons, H. Niu, T.L. King, S. MacDonald, E.C. McIntyre, B. Robinson, S.A. Ryan and G. Wohlgeschaffen. 2011. State of Knowledge Review of Fate and Effect of Oil in the Arctic Marine Environment 2011. National Energy Board of Canada, Ottawa, ON. 267 pp.

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1. Introduction

Despite rapid advances in the development of ocean renewable energy technologies, such as

offshore wind and tidal energy, Canada and the world will remain dependent on petroleum

hydrocarbons to meet future energy needs over the next few decades. With traditional

hydrocarbon reserves in the Western Canada Basin and other areas being depleted, exploration

and production operations within the oil and gas industry have shifted towards frontier regions in

the offshore and Arctic (Figure 1). Based on current analysis, it is evident that the bulk of our

newly discovered petroleum reserves and the best prospects for future discoveries will lie under

water rather than on land. The future of Canadas offshore oil and gas production may also rely

to a substantial extent on finds in deeper more distant locations on the outer continental shelf.

Figure 1 Since 1980 industry has increased the recovery of oil from the offshore sector to meet global demand as land-based oil reserves declined. There is a greater risk of spills and damage as operations expand into the frontier regions including the deep waters off the continental shelf and the Arctic (Sandrea and Sandrea, 2007).

Ocean sector activities related to Canadas oil and gas industry provide major socio-economic

benefits to Canada; $17.7B in direct GDP in 2006. This was linked to the direct generation of

over 171,340 jobs (Figure 2).

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Figure 2 The significance of the oil and gas industry to Canadas GDP in 2006.

Among the greatest uncertainties in future energy supply, and a subject of considerable

environmental concern, is the amount of oil and gas yet to be found in the Arctic. The Arctic is

estimated to contain between 44 and 157 billion barrels of undiscovered recoverable oil. In

addition, the Arctic is gas-prone with an estimated 770 to 2990 trillion cubic feet of undiscovered

conventional natural gas (Bird et al., 2008). By using a probabilistic, geology-based

methodology, the United States Geological Survey examined the area north of the Arctic Circle

and concluded that about 30% of the worlds undiscovered gas and 13% of the worlds

undiscovered oil may be found there, mostly offshore under less than 500 metres of water.

Undiscovered natural gas is three times more abundant than oil in the Arctic and is largely

concentrated in Russia (Gautier et al., 2009). Thus, the Arctic continental shelves constitute one

of the worlds largest remaining prospective areas. To date, the remoteness and technical

difficulty presented by the Arctic, coupled with abundant low-cost petroleum in other regions of

the world, ensured that little exploration of the Arctic offshore reserves occurred. Even where

offshore wells have been drilled, in the Mackenzie Delta, the Barents Sea, the Sverdrup Basin,

and offshore Alaska, most of the resulting discoveries remain undeveloped.

Previous exploration activities by Imperial Oil Limited, Dome Petroleum Limited, Gulf Canada

Resources Limited, and Panarctic Oils Limited between 1960 and 1980 have verified the

presence of significant oil and gas finds in Canadas Arctic waters (SL Ross Environmental

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Research Ltd. et al., 2010). The Drake F76 program (Panarctic Oils Limited) at a water depth of

55 m, approximately 1200 m offshore of Drake Point on the Sabine Peninsula of Melville Island

was the first offshore floating ice platform within Canada. The well at this facility with under-

the-ice subsea tree and subsea diverless connections of flowlines and controls (Bomba and

Brown, 2011) has proven the feasibility of offshore gas production in the Arctic region. The

Drake F76 program has been a showcase for advances in technologies and continues production

today.

With the rising prices and increased global demand for oil has come renewed interest in the

extraction of petroleum hydrocarbons in the Arctic, with the attendant concerns over sovereignty,

energy security, and advances in technology. Indeed, consideration has been recently given to

exploration and production in the deepwater Arctic environment of the U.S. Beaufort Sea (Pilisi

et al., 2011) by the use of winterized drill-ships constructed of material able to withstand the ice,

or an icebreaker converted into a drilling vessel. Increases in oil and gas exploration and

production activities in frontier regions would result in an increased risk of operational and

accidental releases of petroleum hydrocarbons due to the expansion of drilling operations,

marine support and shipping operations including that of pipelines. This risk is further

compounded in the Arctic environment due to environmental challenges including the

interference of ice, cold temperatures, isolated locations, high winds, and low visibility

especially during the winter when there are limited daylight hours. It is also important to note

that the availability of oil spill response personnel, and logistics for waste containment and

disposal in spill response operations, are issues in the Arctic. Furthermore, residents of

communities in Canadas Arctic are concerned over the effects of oil spills on indigenous species

and their habitat, as well as the effectiveness of existing oil spill response strategies that were not

originally designed for use in the North.

Due to the anticipated increase in both offshore oil and gas activities and onshore developments

(e.g. community growth, mining industry, etc.) in the Canadian Arctic, and the recent BP

Macondo MC 252 Deepwater Horizon spill (DWH) in the Gulf of Mexico in April 2010, more

stringent government policies and regulations for environmental protection are being considered.

A primary emphasis of environmental oversight is that of protecting the environment from

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accidental spills. This includes all spills ranging from the small, repeated discharges linked to

routine exploration, production, processing and transport operations, to that of a catastrophic

spill of national or international significance. Within this context there is a demand to

understand the factors and processes influencing the fate and effects of oil released into the

marine environment. This information is essential for the development of improved spill

response and remediation technologies, and contingency plans.

To support a public review of Arctic safety and environmental offshore drilling requirements the

National Energy Board of Canada is looking for the best available information. This report has

been generated by the Centre for Offshore Oil, Gas and Energy Research, which is a Centre of

Expertise within the Science Branch of the Department of Fisheries and Oceans Canada, to

provide scientific facts and information on the fate and effects of oil in the Arctic marine

environment. The scope of the project includes:

review of the properties of oil that have been, or are likely to be discovered in the Arctic, and the identification of chemical parameters that influence oil fate and effects in the

Canadian Arctic offshore or nearshore environment;

reporting on the fate and effect of oil that could be released as a result of accident, mishap (including oil or fuel that would be in support of operational offshore oil and gas drilling

activities), or a well that becomes out of control;

review of relevant reports providing knowledge about the fate and effect of oil spills in Arctic waters and information on the fate and effects of the Exxon Valdez spill in the Gulf of

Alaska;

incorporation of experience and knowledge from previous field studies relevant to offshore oil and gas drilling in the Canadian Arctic;

identification of knowledge gaps that may influence the safety of offshore drilling operations and the protection of the environment; and

recommendations for future research.

To meet the above study objectives, this review is structured in several sections. Chapter 1,

following the Introduction, is focused on the characterization and classification of crude oils

based on physical properties that influence the significance of oil fate and behavior in the

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environment as well as the success of oil spill response strategies. A section of the chapter

describes the characteristics of the crude oils which we anticipate to be recovered within the

offshore Arctic regions of Canada during production operations in the future. Chapter 2 provides

an overview of current observations and scientific findings on the fate and behavior of oil spilled

in Arctic waters. Detailed information is provided on the influence of environmental conditions

such as ice-cover. Chapter 3 covers the subject of oil spills in the Canadian Arctic. The

potential sources of accidental and operational releases in Canadian Arctic waters are described

with risk analysis based on the probability and consequences of various spill scenarios that may

occur during anticipated future operations. Chapter 4 provides an overview of the current oil

spill response technologies available for use in the Arctic environment. Emphasis is given to

emerging technologies currently being developed for specific use in ice-infested waters. Chapter

5 provides a comprehensive review on the biological effects of oil spilled in Arctic waters. This

chapter covers topics such as routes of exposure, bioaccumulation, environmental effects

monitoring, potential changes on community structure and trophic level dynamics. Sub-sections

cover the effects of oil on various groups of organisms ranging from bacteria at the base of the

food web to the top predators such as polar bears and whales. Information is provided on the

environmental significance of valued ecosystem components (VECs) in Canadian Arctic waters

(e.g. polar cod) and their sensitivity to contaminant hydrocarbons. Chapter 6 covers the sources

of the various types of petroleum hydrocarbons that may be released into the Arctic marine

environment from operational activities. The potential environmental impacts associated with

the discharge of production waters and drilling muds are discussed. Chapter 7 describes the

results of experimental field trials conducted in the Arctic which have provided essential

information on the fate and behavior of oil in the environment as well as a platform for the

development and validation of oil spill countermeasures. A discussion on the need for additional

field trials to advance our scientific and technical knowledge is given. Chapter 8 provides a case

study on the impact of the oil spilled in Prince William Sound (PWS) from the grounding of the

tanker Exxon Valdez, oil spill response operations and the current controversy among various

parties over the extent of habitat recovery. Based on the information in this report, a list of

future research needs is presented in the final chapter to address the knowledge gaps that have

been identified.

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2. Characterization and Classification of Crude Oil

2.1 Physical and Chemical Properties

Crude oils are complex mixtures comprised of hundreds to thousands of individual compounds.

However, the hydrocarbon content of crude oil can be separated into four main classes: saturates,

aromatics, resins (includes waxes), and asphaltenes (Fingas, 2010; Hannisdal et al., 2007). For

quantitative analysis, gas chromatography-mass spectrometry (GC/MS) can be used to

characterize the individual components of saturates, aromatics and biomarkers in crude oil, while

the resin and asphaltene content is usually measured using thin layer chromatography coupled to

flame ionization detection, or TLC-FID (Obermajer et al., 2010).

The chemical composition of crude oil influences its physical properties, which impact its fate

and transport properties on release into the marine environment. For example, a high content of

resins and asphaltenes will increase the viscosity making it less mobile. Crude oil chemical

composition can also affect the rate of biodegradation where microbial attack has generally been

ranked in the following order of decreasing susceptibility: saturates > aromatics > resins >

asphaltenes (Leahy and Colwell, 1990). Crude oils also contain a number of compounds referred

to as biomarkers, such as steranes and hopanes, which are persistent and less susceptible to

microbial attack. Since every crude oil has a unique biomarker profile, quantification of these

compounds provides a means for the identification of the origin of unknown oils in spill response

operations, provided that a database of oil biomarker profiles exists (Wang and Fingas, 1995). In

addition, other chemical components that are susceptible to biodegradation can be normalized to

these biomarkers to determine if changes in oil composition are linked to physical processes or

biodegradation (Prince et al., 2003b).

Physical properties, which are dependant on the chemical properties, can be used to characterize

crude oils. The main oil properties to take into consideration in an Arctic oil spill scenario, since

they are temperature dependant, include the American Petroleum Institute (API) gravity values,

viscosity, pour point, distillation characteristics, surface tension, flash point, and weathering

9

(ITOPFL, 2002; Payne et al., 1991; Shata, 2010). Definitions for these parameters are provided

here to better illustrate their significance in describing the physical properties of oil.

The specific gravity of oil is its density compared to seawater which is on average 1.025 g/mL. Most oils have a specific gravity 31, medium oils have an API gravity between

22 and 31, and heavy oils have an API gravity medium oil > heavy oil. Temperature can affect viscosity (Figure

3). As the temperature falls, oil becomes more viscous (less mobile) and persistent in the

marine environment (Brandvik and Leirvik, 2008). In some cases, the rheological properties

(deformation and flow) of heavy oil can be altered using lighter fuels (Elasheva et al., 2001;

Schmidt et al., 2005). This process increases the commercial value of heavy oils and

decreases the viscosity, which improves mobility of the oil during transport (Elasheva et al.,

2001; Schmidt et al., 2005).

10

0123456789

10

0 5 10 15 20 25 30

Temperature ( C)

Cen

tiPoi

se

Figure 3 Norman Wells crude oil dynamic viscosity as a function of temperature; data from Environment Canadas Oil Properties database (Environment Canada, 2001a).

Pour point is the temperature below which oil will not flow (ITOPFL, 2002). The waxy (resins) and asphaltenic components affect the pour point of oil. As the temperature of the

oil decreases, the wax components crystallize. This is often referred to as the cloud point.

This process hinders the flow of oil until it eventually changes from a liquid to a semi-solid

at the pour point (ITOPFL, 2002). The pour point is used to evaluate the flow of crude oil at

low temperatures (Zhang and Liu, 2008).

Distillation characteristics (evaporation) of crude oils describe their volatility (ITOPFL, 2002). As the temperature increases the low boiling point components, i.e. benzene, toluene,

ethylbenzene and xylenes, begin to evaporate or distil. Evaporation loss by weight or

volume is logarithmic with time for multi-component mixtures (Bobra, 1992; Fingas, 1994;

Fingas, 1999). The waxy and asphaltenic components of crude oil will not distil under

ambient conditions and remain persistent for extended periods in the environment.

Evaporation can change the physical and chemical composition of fresh crude oil.

Surface tension is the amount of pressure necessary to break the surface of a liquid. The oil/water interfacial tension is the force of attraction between the surface molecules of the

oil and the water (Shata, 2010). The lower the interfacial tension at the seawater-oil

interface, the greater the extent of oil spreading (Fingas, 2010; Fingas and Hollebone, 2003;

11

The flash point is the lowest temperature at which an oil will ignite (Brandvik and Leirvik, 2008; Shata, 2010). This property is dependant on oil composition, in particular the volatile

components. The volatiles are generally lost due to evaporation; however, this process is

temperature dependant. In cold water, evaporation of oil is slow and the volatiles remain.

Fresh crude oils normally have a low flash point from -40 to 30C (Brandvik and Leirvik,

2008). If the flash point of crude oil is close to or lower than sea temperature then there is a

risk of fire or explosion hazard (Brandvik and Leirvik, 2008).

Weathering describes a series of natural physical and chemical changes that oil undergoes following its release into the environment. Weathering of oil depends on the type of oil

(physical and chemical properties), environmental conditions (wind, waves, temperature and

sunlight), the properties of seawater (salinity, temperature) and the presence of biodegrading

microbes such as bacteria (Brandvik and Leirvik, 2008). The main environmental processes

that encourage weathering are oxidation, dispersion, dissolution and sedimentation, and

evaporation which lead to the disappearance of oil from the sea surface (see Section 3.2

Behaviour and Fate of Oil).

2.2 Significance of Oil Properties in Oil Spill Response

Oil properties will directly affect the fate and behaviour of oil spilled in the environment as well

as the effectiveness of spill response operations. Crude oil would be presumably more persistent

in Arctic waters because evaporation is slow, and spilled oil can become trapped under ice

making it less accessible to oil degrading bacteria and decreased weathering (Leahy and Colwell,

1990; Shata, 2010). At low temperatures oil becomes more viscous, the toxic short chain

volatiles remain intact and their solubility decreases, slowing the biodegradation process (Leahy

and Colwell, 1990). Environmental conditions in the Arctic may hamper the efficacy of current

oil spill response operations. The presence of ice may dampen the wave energy within ice floes

to a level below that required for effective chemical dispersion, precluding the use of chemical

dispersants as a spill response option (Deshpande et al., 2005; Shata, 2010). In addition, the

physical properties controlling dispersant effectiveness, namely the lowering of the surface

12

tension of seawater permitting oil to be broken into small droplets with wave energy, are less

effective in Arctic waters since surface tension and oil viscosity both increase with decreasing

temperature. The result is a thicker oil slick requiring more wave energy to disperse (Deshpande

et al., 2005; Glover and Dickins, 1999). On the other hand, there can also be some advantages to

consider when oil is spilled in ice infested waters (Shata, 2010). In areas where ice cover

provides boundaries, oil dispersants may be used as herding agents where they are sprayed

around the periphery of thin oil slicks, thus contracting the oil into a thicker slick (SL Ross

Environmental Research, 2010). The colder waters and increased thickening (viscosity) of the oil

decreases evaporation with the volatile components remaining in the oil, which maintains a low

flash point (Glover and Dickins, 1999; Shata, 2010). This provides an ideal environment for in

situ burning (Shata, 2010). In cold environmental conditions, oil persists longer, increasing the

time window for mechanical oil spill recovery operations and the application of other

remediation technologies (Shata, 2010). The formation of emulsions, where seawater becomes

suspended in oil, occurs slowly under ice cover due to damping of the waves (Shata, 2010).

Where emulsions occur, the selection of the appropriate spill response countermeasure will be

largely dependent on the process that stabilizes the emulsion (Friberg, 2007). In the event of a

deep sea well-head blowout such as the DWH, both pressure and temperature would influence

the subsequent fate and effect of the crude oil released (Leahy and Colwell, 1990).

2.3 Canadian Arctic Offshore Crude Oils

Northern Canada is potentially rich in oil and gas resources. Indeed, oil and gas has been

discovered in Baffin Bay, the Arctic Islands, the Mainland Territories, and the Beaufort-

Mackenzie Basin (Drummond, 2006). A total of 1544 wells were drilled in the Canadian Arctic

prior to 2004, and of these, 944 were exploratory (Drummond, 2006). There is an enormous

global demand for energy resources, and given our national demand for energy and potential

economic gains for Canada, the recovery of petroleum resources in the Arctic is now a priority

issue shared by government and industry. In order to assess the potential environmental impacts

from the production and transport of crude oil in Arctic waters, it is important to identify and

classify crude oils from the area to provide the information required for risk assessment and spill

response operations in the event that an accidental spill should occur.

13

In Northern Canada, a variety of oils have been identified for commercial production. These oils

are listed in Table 1. The origin of crude oils can greatly affect their physical and chemical

properties. Crude oils from the Arctic have been classified according to their API gravity values

with the aid of Environment Canadas database on oil properties (Environment Canada, 2001a;

Jokuty, 2001). Further information can be obtained from the database (Environment Canada,

2001a), which contains information on 450 oils. There is also a Spilltox database containing

toxicity data on over 30 crude oils (Environment Canada, 2001b). The hydrocarbon content of

crude oils can vary depending on the origin of the oil. Hydrocarbon content affects the physical

properties of Arctic oils, which for the most part determine the fate, effects, and transport of

spilled oil at sea.

There is considerable interest in defining the composition of a reference surrogate oil for use in

predictive numerical models on the fate, transport and effects of oil spills in the Arctic for risk

assessment purposes. Most of the crude oils harvested in the Arctic Region have an API gravity

greater than 22; therefore, it is recommended that a light or medium grade oil be selected from

the list in Table 1 to model the environmental impacts of an accidental oil spill in cold Arctic

waters. Based on the chemical composition of the crude oils found in the Arctic Region,

Atkinson crude has the highest aromatic content (Table 1). Unfortunately, as noted in the table,

the level of information on the chemical content for many of the crude oils recovered in the

Arctic is limited. Crude oil toxicity to marine life is associated with its aromatic content, namely

the polycyclic aromatic hydrocarbon (PAH) compounds containing 1-3 rings in the chemical

structure, and their alkylated homologues (Miller et al., 1982; Van den Heuvel Greve and

Koopmans, 2007). Based on the toxicity classification scheme by Van den Heuvel Greve and

Koopmans (2007), the three crude oil classes (light, medium and heavy) can be defined as

follows.

1. Light crude oil (low density, high toxicity): API gravity > 40

2. Medium crude oil (medium density, medium toxicity): 28 < API gravity < 40

3. Heavy crude oil (high density, low toxicity): API gravity < 28

14

Table 1 Canadian Arctic oils (Drummond, 2006).

Hydrocarbon Groups (%weight)1 Origin Well API1 gravity

Class S A R A

Beaufort Sea Adgo 16.8 heavy 89 19 1 1 Beaufort Sea Amauligak 27.4 medium 90 9 1 Beaufort Sea Atkinson 23.7 medium 46 36 15 3 Beaufort Sea Issungnak 35.0 light 92 3 0 0 Beaufort Sea Koakoak 29.5 medium NA NA NA NA Beaufort Sea Kopanoar 25.7a medium NA NA NA NA Beaufort Sea Nektoralik 24.5 medium NA NA NA NA Beaufort Sea Nerlerk 23.9 medium NA NA NA NA Beaufort Sea Tarsiut 30.1 medium 92 7 0 0 Beaufort Sea Ukalerk 45.7 light NA NA NA NA Beaufort Sea Uviluk 29.4 medium NA NA NA NA Northwest Territories

Bent Horn 41.3 light 94 5 7 0

Northwest Territories

Bent Horn A-02 41.5 light NA NA NA NA

Northwest Territories

Norman Wells 38.4 light 86 11 3 1

Beaufort Sea Adlaktok P-09b 30 light NA NA NA NA MacKenzie Delta

Garry P-04b 45 light NA NA NA NA

MacKenzie Delta

Hansen G-07b 22-57 light - medium

NA NA NA NA

Beaufort Sea Isserk I-15b 20-21 heavy NA NA NA NA MacKenzie Delta

Kugpik O-13b 45-49 light NA NA NA NA

MacKenzie Delta

Mayogiak J-17b 33 light NA NA NA NA

Beaufort Sea Nipterk L-19b 18-21 heavy NA NA NA NA Beaufort Sea Nipterk P-32b 29 medium Beaufort Sea Pitsiulak A-0 b 30 light -

medium NA NA NA NA

MacKenzie Delta

Tuk J-29b 32 light NA NA NA NA

MacKenzie Delta

W. Atkinson L-17b 27 medium NA NA NA NA

1Environment Canada oil properties database, 2001 acalculated from specific gravity bpeer communication AEB NA - not available

In this case, it is important to note that reported API gravity values used to classify the oils do

not conform to that defined by the American Petroleum Institute (ITOPFL, 2002). SINTEF

critically reviewed the classification provided and reported that it was not fit for operational

purposes as the heavy oil was more toxic than light oil (Van den Heuvel Greve and Koopmans,

15

2007). In contrast, data taken from Environment Canadas Spilltox database supported this

classification system (Van den Heuvel Greve and Koopmans, 2007). While API gravity values

aid in the classification of crude oils, the chemical composition of the oil is crucial for

environmental risk analysis since a high aromatic content may be an indicator of toxicity. Both

parameters provide essential information for the assessment of the potential impacts that a spill

will have in Arctic marine waters. Based on current information, the fate, effects and transport

of an accidental oil spill in cold Arctic waters can be adequately assessed using either light or

medium grade oils, such as Atkinson crude, as a surrogate to assess environmental impacts and

the efficacy of various oil spill remediation technologies.

16

17

3. Oil Spills in Arctic Waters

3.1 International Concerns and Governance For the past 40 years the potential for pollution of the sea by accidental releases of oil has been a

concern of many national governments and other organizations. Despite advances in technology

and the implementation and enforcement of appropriate regulations and good working practices,

an expansion of shipping activity, and oil exploration and production will increase the risk of an

accidental oil spill. While we can minimize this risk, we cannot totally eliminate it. The recent

Arctic Marine Shipping Assessment Report completed under the leadership of the Arctic Council

Ministers Working Group on Protection of the Arctic Marine Environment has provided an

overview of ships and their infrastructure needs, and impacts in the Arctic Ocean (Fretheim et

al., 2011).

Contrary to that anticipated for offshore oil and gas exploration and production facilities, the

majority of marine traffic operations will occur in Arctic waters that are either permanently or

seasonally open. Nearly all current shipping activities take place on the periphery of the Arctic

Ocean, away from permanent or drifting ice. In other areas of the Arctic which have seasonal ice

cover, nearly all vessel activity occurs when and where the ice has melted or is melting so that

icebreakers are not required for assistance. The changing climate in the Arctic region is also

leading to a reduction in ice coverage that may increase the frequency of marine shipping traffic

and the risk of accidental oil spills.

The Arctic Marine Shipping Assessment reaffirmed the Arctic states view that the United

Nations Convention on the Law of the Sea remains the legal framework that influences and

guides current and future governance of the Arctic Ocean and also acknowledged that the

International Maritime Organization is the lead, and appropriate, UN body that can focus on

marine safety and environmental protection measures for the global maritime industry, including

operations in the Arctic. The Behaviour of oil and other Hazardous Substances in Arctic

waters project under the auspices of the Arctic Council has gathered and synthesized the current

knowledge and expertise on the behaviour of oil and other hazardous and noxious substances

released into Arctic waters resulting from accidental spills (Bjerkemo, 2011). The project

promoted the development and use of technologies and working methods to improve our

international capability to respond to accidents involving the spill of potential toxic

contaminants.

3.2 Behaviour and Fate of Oil

Various chemical and physical processes govern the fate and behaviour of oil following a spill in

the environment. It is important to note that the presence of seasonal ice has a significant effect

on oil weathering in the Arctic. It is thus important to distinguish the fate and behaviour of oil

during the winter season when ice is generally present, from when ice is absent or less

concentrated during the spring-summer season.

Weathering processes will change the oil and affect its properties and behaviour. Oil type and

environmental conditions such as temperature, sea state, winds, and other factors play an

important role in how the oil will weather over time. In some cases, these processes will

contribute to the natural removal of oil from the environment while in others they will contribute

towards the persistence of residual oil. Knowledge of oil behaviour is essential for the

identification of efficient response strategies at the time of a spill.

Work through the 1970s and 1980s largely focussed on questions related to oil behaviour and the

capture of oil under ice following a large blowout. Comprehensive reviews noted that during this

period, six full-scale field trials, twelve small-scale laboratory studies of oil and gas under static

ice, six studies of water current transport of oil under ice, and nine studies of oil on new ice-

growth were conducted (Dickins, 1994; Fingas and Hollebone, 2003). The majority of these

studies produced empirical relationships of oil spreading behaviour. The primary results were

that the oil spreading under ice was much slower than on the water surface alone and that the

extent was governed mostly by the shape of the under-ice surface. During the last two decades,

laboratory and mesocosm (including wave tank) studies, field tests and modelling efforts, have

been expanded to provide insights on the interactions that occur when oil, and oil and gas

18

mixtures are discharged in waters where ice is present. Much has also been learned from spill

response operations following accidental spills in ice-infested environments. A number of

literature reviews on the fate and behaviour of oil in icy waters have been compiled over the past

20 years (Fingas, 1992; Dickins, 1994; Reed et al., 1999; Fingas and Hollebone, 2003; Gjsteen

et al., 2003; Yapa and Dasanayaka, 2006; Brandvik, 2007; Khelifa, 2010; SL Ross

Environmental Research, 2010; Dickins, 2011). This review and that of Drozdowski et al.

(2011) summarize the current state-of-knowledge from studies to date, and how they might be

used to predict the behaviour of oil spills in the Arctic.

Oil in Ice-Free Waters

Ice coverage in the Arctic in most areas is seasonal. Generally, ice formation will take place

around September to October, and will start melting and breaking up around April to May.

During the summer months many areas are either free of ice or with ice concentrations of less

than 10% (drift ice). There are many possible scenarios in which an oil spill can occur, such as

sub-sea blowout, sub-sea pipeline leaks, oil tanker grounding or collision incidents, crude oil

leaking during loading and unloading, and bunker fuel releases. The fate and behaviour of oil

spilled in open water (ice-free) conditions has been extensively studied and described in many

forums and review papers (Huang, 1983; IMO (International Maritime Organisation), 1988;

ITOPFL, 1986; Reed et al., 1999; Spaulding, 1988; Yapa and ASCE Task Committee on

Modelling of Oil Spills, 1996).

Oil behaviour in ice-free Arctic waters is similar to oil behaviour at lower latitudes. The main

processes affecting oil behaviour in ice-free waters are summarized in Figure 4. As soon as oil is

spilled into the environment, it starts spreading on the sea surface, forming a thin layer. The

speed and extent at which the oil spreads will depend largely on its viscosity and on the quantity

spilled. Low viscosity oil will spread faster than high viscosity oil. Most crude oils discovered

so far in the Canadian Arctic are of medium viscosity. Low Arctic summer temperatures might

contribute to elevated oil viscosity and reduced spreading.

19

Once oil spreads and forms thin oil slicks, these start to fragment into smaller slicks or narrow

bands (windrows) under the influence of winds, waves and currents. At the same time, volatile

components evaporate into the atmosphere. Warm temperatures, high wind speeds and rough

seas will increase the rate of evaporation. Spreading and evaporation share a close relationship.

As oil spreads, the surface area of the slick will increase, increasing the evaporation rate.

Generally, refined products of low viscosity such as diesel or aviation fuel will evaporate more

rapidly than most crude oils. During the season in which Arctic waters are free of ice, low water

temperature still plays a significant role in determining the oil weathering rate. Colder

temperatures increase the viscosity of the oil, which affects spreading and dispersion but also

reduces the evaporation rate. In these conditions, an oil spill in ice-free water will behave as it

would in warmer conditions, but with a reduced weathering rate.

Figure 4 Physical, chemical and biological processes affecting the fate and behaviour of spilled oil (ITOPFL, 2002).

Natural dispersion will occur when turbulence generated by waves is sufficient to break up the

oil slick into small droplets of various sizes. These become entrained into the water column

where they mix in the upper layer and become diluted by the turbulent energy of the sea.

Eventually, these dispersed droplets are biodegraded by microbial organisms. However, in order

for this process to occur on a significant scale, oil droplets must average < 70 m diameter in

size, as larger droplets will recoalesce, come out of suspension and form a slick, which reduces

20

the surface area of the oil available to microbial attack. This process is largely dependent on oil

viscosity and sea state. Natural dispersion is more likely to happen with low oil viscosity (usually

Group 2 oil, API gravity > 40) and a sea state generating small breaking waves.

Biodegradation is the process by which microorganisms already present in the sea will use oil as

a carbon source and metabolize petroleum compounds. Biodegradation is a significant

weathering process when the oil is either dispersed into small droplets or broken up in a very thin

film. It is not a significant process when oil is highly viscous, remaining in thick slicks, or when

emulsification has taken place. It mainly occurs with light to medium oils in which hydrocarbon

chains are relatively short. Heavier oils with high wax or asphaltene content are difficult to

biodegrade. Biodegradation is a relatively slow process that necessitates the presence of

microorganisms, nutrients and oxygen. The rates are usually assumed to be slow in cold water

environments based on the majority of past microbiological studies. However, recent studies

under low temperature conditions including the Arctic, ice infested waters, and at deep ocean

depths (Hazen et al., 2010; Lee et al., 2011c; Lee et al., 2011d) have also shown significantly

rapid oil biodegradation rates.

Emulsification is another process that is likely to occur as oil slicks are drifting on the sea

surface. With the turbulent energy from waves, some oils will take up water droplets to form an

emulsion of water in oil. Emulsification usually forms in oil with a nickel or vanadium

concentration greater than 15 ppm, or an asphaltene content of more than 0.5%. However, the

most significant factor will be the presence of waves usually generated by a sea state of Beaufort

3 or above. Emulsions are usually very viscous and increase in volume up to four times the

volume of the original oil. They are also very persistent since other weathering processes are

greatly reduced once they are formed.

The weathering processes summarized in the preceding paragraphs occur as soon as oil is spilled.

Their relative importance varies mainly according to oil type and weather conditions. Oxidation,

dissolution and sedimentation can also take place during an oil spill, but in most cases, these

particular weathering processes play a limited role in the ultimate fate of oil. Sedimentation is

more likely to happen in the nearshore environment where oil becomes associated with

21

suspended particulate material including sediments which would facilitate its transport to the

seabed. Dissolution is likely to happen with light oils or refined products as these products have

a higher concentration of light compounds that are soluble.

Oil in Ice Covered Waters

All of the scenarios that occur in open water conditions could occur in locations where ice is

present; therefore, oil could be released under ice cover from a sub-sea leak or blowout, or onto

the ice surface (for example from a platform blowout), or in waters with ice floes. Numerous

field and laboratory research projects have been conducted since the 1980s to study oil

weathering in ice-covered waters. These have shown that oil is subjected to the same weathering

processes mentioned in the previous section. Because of the cold temperatures, oil viscosity will

generally increase for all oil types; however, interaction of oil with ice will affect the rate at

which these processes are taking place. Natural dispersion and emulsification are largely

dependent on wave energy in order to take place. The presence of ice will have a significant

impact, as short waves will be damped by ice floes, greatly reducing the rates of natural

dispersion and emulsification. In water with an ice coverage greater than 60%, the ice may

effectively contain and reduce oil movement, and thus protect sensitive shoreline resources.

Evaporation and biodegradation still take place in ice-covered water, but the low temperatures

usually associated with the presence of ice reduce the rate at which they occur.

Direct interaction of oil with ice affects its behaviour. Figure 5 summarizes the multiple ways oil

can interact with ice. The presence of ice greatly complicates the possible fate of oil spilled in

Arctic waters. The behaviour of oil in ice is complex, and the difficulties in modelling the

physics of ice formation and movement on scales of metres are magnified when the uncertainties

of oil behavior are added. If oil is spilled on ice, evaporative loss will be the main weathering

process as spreading will be limited by ice surface roughness and by absorption into snow.

Because of this, oil accumulations on the ice surface are expected to be limited in area and fairly

thick. For lighter oil types, absorption by snow could be a significant process depending on the

quantity of snow on the ice surface.

22

Figure 5 Oil and ice interaction processes (Bobra and Fingas, 1986).

Oil spilled under the ice is subject to various processes (Figure 5). In most cases, oil will drift

under the ice layer because of the currents and movement of the ice floes and will eventually

accumulate in naturally formed reservoirs due to ice roughness. These will vary in size but

significant quantities of oil could be trapped under the ice in this manner. Some of the oil could

be dislodged by currents and continue to drift under the ice. Several studies have set the

threshold for movement of oil under ice at 0.5 kt (26 cm/s). Oil can become encapsulated within

the ice structure in winter conditions when new ice is being formed. In some cases, this process

can happen rapidly (within 18 to 72 h) once oil is trapped under the ice. It is important to note

that oil weathering processes are inhibited by the encapsulation of oil. In springtime with

melting and warming of the ice sheet, encapsulated and trapped oil can migrate vertically

through brine channels and reach the surface of the ice to form pools of fresh oil. The rate of

vertical migration largely depends on the number of brine channels in the ice sheet and the oil

viscosity.

The lower oil weathering rate generally observed in ice-covered waters could represent an

advantage for response effectiveness in some spill scenarios. Reduced spreading in icy

23

conditions could increase the window of opportunity for certain response techniques (chemical

oil dispersant applications, for example) and be a significant advantage in the Arctic, since

residual oil would remain in an unweatherd state longer than it would under ice-free conditions.

However, the presence of ice in itself represents a great operational difficulty that can offset the

advantages provided by the reduced weathering rate.

3.3 Factors Influencing Oil Behaviour

Numerous field, laboratory and tank studies have been conducted over the past 30 years on the

behaviour of crude oils and refined products (including fuel oils) spreading in, on, and under ice.

A good understanding of the basic processes controlling the behaviour of fresh and weather oil,

and the development of numerical models to describe their time-series changes have been gained

from these efforts, and are reviewed by Lewis (2000), Fingas (2003), Yapa et al. (2006) and

Drozdowski et al. (2011).

Spreading in Broken Ice

An oil spill on a calm water surface spreads by gravity and is resisted by inertia, viscosity, and

surface tension until the slick reaches a thickness of approximately 0.1 mm (NRC, 2005). As

noted previously, the spreading speed is determined by many factors. Light crude oil spreads

much faster than heavy fuel oil, and wind, waves and currents can significantly increase the rate

of spreading. A rough sea with high mixing energy will significantly enhance this effect.

In cold regions, the spreading of oil can be significantly affected by the presence of snow and

ice. In broken ice, oil is assumed to move at the water surface, flowing around any ice present.

Oil can pile up and thicken around ice flows, and if sufficiently confined, may begin to flow

under the ice at the ice-water interface. It has been noted that for ice concentrations less than

30%, oil behaves as in open water (Deslauriers, 1979; ITG, 1983; SL Ross Environmental

Research Ltd. and DF Dickins Associates LLC., 1987; Venkatesh et al., 1990). For ice

concentrations greater than 30%, the oil is found to drift with ice. The equilibrium oil thickness

in slush or brash ice (accumulations of the wreckage of other forms of ice made up of fragments

24

not more than 2 m across) is nearly four times that on cold water, which itself is very different

from that on warm water. As a result, the oil-contaminated area at higher ice concentration is

several orders of magnitude smaller.

In tank tests, Martin et al. (1976) observed that both diesel oil and Prudhoe Bay crude oil

surfaced readily when poured into grease ice and slush, and they calculated an equilibrium

thickness of 1 mm for diesel oil in a mixture of pancake and grease ice. Sayed and Lset (1993),

studying the spreading of oil on water and among brash ice in moderate to high concentrations,

showed that the ice confined the oil to between 5/10 and 8/10 of surface coverage, increasing the

slick thickness and limiting the final equilibrium extent of the oil. A modified Fay equation for

spreading based on the results of small field spills represents the most suitable analysis to date.

In brash ice, spreading rates decrease with increasing ice concentrations and the presence of

slush ice strongly reduces the spreading, but the effect is small for ice concentrations below 20

30% (Gjsteen and Lset, 2004). Increased motion in the ice cover resulted in increased

spreading rates, and this effect was especially pronounced in the presence of slush. Decreased

spreading rates due to increased oil viscosity were also observed.

In terms of developing predictive models, Gjsteen and Lset (2004) measured spreading rates

of marine fuel oils in slush and frazil ice with different wave energies. It was clear that the

presence of broken ice significantly slowed oil spreading. Gjsteen (2004) developed a

mathematical model using Newtonian viscosity to predict the spreading of oils over water and

slush ice, and found good agreement with the lab data of Sayed and Lset (1993). The model

was reportedly coupled to a discrete-element ice model. Hara et al. (2008) developed a model

for flow of oil through a broken ice field, and included a specific term for the critical thickness of

oil which will begin to flow under the ice, rather than through the broken ice field, dependent on

the oil and water densities and the oil-ice-water interfacial tension. This model has not yet been

tested.

Lewis (2000) concluded that at lower ice coverage (< 30%), the oil and ice will move at different

rates under the influence of wind. The influence of wind on an oil slick is to increase the

movement of the slick by approximately 3%, while ice floes tend to move the slick faster (4.5 to

25

6%). At ice concentrations greater than 50%, oil drifts with ice at speeds from 4 to 7% and the

rate decreases as the ice concentration increases.

Field experimental data on oil spreading under various broken ice conditions (4/10, 5/10 and >

9/10 coverage) has been reported (Buist and Bjerkelund, 1986). With increased coverage of

brash ice, oil spreading was dramatically reduced. A phenomenon described as lead pumping

was reported to redistribute oil from the water to the ice surface under dynamic conditions. The

effects of lead closure rates on the vertical movement of oil were studied by MacNeil and

Goodman (1987) in an outdoor basin. It was observed that oil was forced under the ice when a

lead closed slowly. At high closure rates (above 12 cm/s) most of the oil was forced to the top

surface of the ice.

Weerasuriya and Yapa (1993) and Yapa and Belaskas (1993) experimented with spreading of oil

under and over simulated broken ice fields in small tanks. Based on the laboratory observations it

was concluded that the behaviour of oil spilled under a fragmented ice cover depends on the type

of ice cover. While oil may penetrate completely through one type of cover, it may not penetrate

another.

In 1993, numerous authors reported on test tank experiments and a subsequent experimental spill

of North Sea crude in the Barents Sea marginal ice zone off the coast of Norway (Jensen, 1994;

Reed and Aamo, 1994; Singsaas et al., 1994). High concentrations of pack ice (90% initially,

declining to 75% at the end of the experiment) kept the oil thick and immobile for days which, in

combination with cold temperatures and the damping of wave action by the ice, significantly

slowed oil weathering processes (evaporation, natural dispersion and emulsification). Brandvik

(2006a) presents a comparison between the results obtained from the experimental spill in pack

ice with a similar experimental spill in open water.

26

Movement on Ice

The spreading of oil on ice is more similar to spreading of oil on land than on the sea, and the

slick is much thicker (Lewis, 2000). The spreading rate for oil on ice is determined by the oil

density and viscosity as well as the roughness of the surface over which the oil is spreading.

Discrete ice deformation (rafting, rubble, pressure ridge) may lead to a contained, thick, oil pool.

Glaeser and Vance (1971) is probably the earliest reference to oil spills on ice. It was found in

their study that the ice surface adsorbed the oil to a saturation level of about 25% and the degree

of spreading is a function of spill volume and spreading time. Spreading is also affected by

temperature (Chen et al., 1976). There was no spreading below -19oC and warm oil spread more

rapidly. Another early study on oil spreading on ice concluded that gravity is the only important

spreading force and the final radius is only a function of time (McMinn and Golden., 1973).

Additional new papers have been written on oil spill spreading on ice (Brandvik and Faksness,

2009; Dickins et al., 2011; Jaraula et al., 2008; Peishi et al., 2011; Wang et al., 2008).

Movement Under Ice

Oil pooling immediately underneath the ice layer has been observed in laboratory experiments

(Payne et al., 1991) and field trials (Dickins et al., 2008). A site specific study (Ramseier and

Rene, 1973) showed that with water currents near the North Pole, the oil spreading rate under ice

was 800 cm/day. Chen et al. (1976) observed the spreading of oil under a freshwater ice sheet in

a small test tank and found that the radius of oil is affected by the water density, water or oil

viscosity, time, and volume rate of oil flow to the slick. If oil is in direct contact with the

underside of the ice, oil viscosity is important. The spreading rate was proportional to the

power of the elapsed time in the absence of current. In the presence of strong current, oil droplets

travelled some distance before rising, and many droplets did not adhere to the ice (Fingas and

Hollebone, 2003).

It was reported that the effect of an ambient current on oil transport under ice is much greater

than effects due to forces such as buoyancy, viscosity, and interfacial tension (Uzuner et al.,

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1979). However, some have argued that buoyancy and viscosity are the dominant forces for oil

spreading under ice (Yapa and Belaskas, 1993; Yapa and Chowdhury, 1990).

Buist et al. (1981) studied the behaviour of oil and gas release under ice in the Beaufort Sea. It

was observed that oil broke into droplets as the oil and gas mixture left the discharge pipe due to

turbulence. As the gas rose out of the jet stream it quickly collected in a pocket under the ice. For

the under-ice oil and gas injection study at a gas to oil ratio of 150:1, it was observed that oil rose

in the form of pendent drops of 1 or 2 cm in diameter. With currents of 14 cm/s in the flume

tank, oil began to migrate downstream. Another study involving gas as well as oil under ice is

the work done by Purves (1978). For a 60:1 ratio of gas to oil released under ice in a test tank, it

was found that the presence of gas helped the oil to spread more rapidly and thinner.

It was summarized by Fingas and Hollebone (2003) that in low currents, the oil released under

ice will spread upon reaching the under ice surface due to combined actions of buoyancy,

viscosity and surface tension. A number of force-balance models have been developed to predict

spreading under a smooth ice bottom (reviewed in Fingas and Hollebone 2003). However, in

practice, sea-ice is characterized by significant under-ice roughness, and the final under-ice

configuration is determined by the under-ice roughness and topography. Oil has been observed to

spread systematically, filling the nearest under-ice depressions first before overflowing into the

next depression. Malcolm and Cammaert (1981) calculated the pool thickness of crude oil under

ice in sea water, and the thickness ranged from 4.27 to 10.63 mm for interfacial tension ranging

from 10 to 30 dynes/cm. Local ice conditions are much more important to the final oil

disposition than microscale spreading behaviour. A volumetric analysis is considered to be the

most effective approach for predicting the spread of large oil and gas discharges under an ice

sheet, and several general spreading models have utilized this method. The key parameters are

oil and gas volumes, under-ice storage capacity, and potential for gas expansion.

Oil under stationary or land-fast ice spreads according to not just the fluid property factors, but is

also governed by currents and the under-ice topography. Several field observations have noted

that, in the absence of small currents, the deposition and spreading of oil under continuous ice is

largely governed by the shape of the under-ice surface. An early approach to estimating the oil

28

volume holding capacity of ice for oil was to estimate the volume above the mean draft level of

the under-ice surface. Based on measurements of under-ice topography (Goodman et al., 1987;

Kovacs et al., 1981), this geometric filling approach implied that oil spills under ice would be

confined to a much smaller area than spills in open water (Dickens et al., 2008). Note that these

models considered the final geometric holding capacity of the under-ice topography only, and