Evaluating the Biodegradability and Effects of Dispersed Oil using Arctic Test
Species and Conditions: Phase 1 Activities
Kelly M. McFarlin and Robert A. Perkins
Institute of Northern Engineering, University of Alaska Fairbanks
Fairbanks, Alaska, USA
raperkins@alaska.edu
William W. Gardiner and Jack D. Word
NewFields Northwest
Port Gamble, Washington, USA
Abstract
In the event of a marine oil spill, managers must decide on response actions
such as natural recovery, mechanical recovery, in situ burning, and/or chemical
dispersion. A Net Environmental Benefit Analysis (NEBA) is a structured
examination of various spill response actions and their net environmental effects on
key resources and habitats. Estimating effects of various oil response actions on
marine life and developing input parameters for NEBA models and alternative
assessments during spill events is vital to this examination. This requires information
about the sensitivity of relevant species under conditions following various spill
response techniques. For a hypothetical spill scenario in the Beaufort and Chukchi
Sea, key input parameters for a NEBA model include the relative toxicity of oil and
dispersed oil to local species, change in toxicity with weathering and dispersion of
petroleum, as well as the rate of petroleum biodegradation. A Joint Industry Program
was established to collect these parameters and this paper discusses the first phase of
completed research. Phase 1 activities included determining relevant species to the
Beaufort and Chukchi Sea ecosystems, creating and setting up a toxicity and
biodegradation laboratory with a cold room in Barrow, Alaska, developing collection
and culture methods for test organisms, and developing toxicity and biodegradation
test protocols. This project is ongoing and will provide toxicity and biodegradation
information for use in NEBA types of assessments.
1
Introduction
In 2008, the United States Geological Survey reported that 13% of the worlds
undiscovered oil and 30% of undiscovered gas is located within the Arctic Circle
(Bird, 2008). Spill prevention techniques and response options are important
considerations of exploration and production operations. In the event of a major oil
spill, several cleanup options are usually considered. Mechanical containment and
recovery is usually the preferred option, although this method also has its challenges.
The recovery rate for mechanical skimmers is very low at oil thicknesses less than 1
mm (NRC, 1989). Burning is another useful response option, but in order to burn,
the oil slick thickness must be greater than 1mm (Buist, 2004). Natural dispersion and
attenuation via biotransformation can also be a viable option. The application of
chemical dispersants has many environmental advantages under certain conditions
and research is being conducted for the Beaufort and Chukchi Sea as well as the
Barent’s Seas to provide site-specific information on toxicity and biodegradation
rates associated with chemically dispersed petroleum. All of this information then
becomes available for response managers and resource trustees before, during and
after a spill to develop the most environmentally effective response, or combination
of responses, to reduce the overall consequences of the spill (Aurand et al., 2000).
The NEBA-like processes provide the basis for comparing and prioritizing risk,
especially when trial assessments are held under pre-spill workshops like those
conducted by NOAA (Aurand and Coelho, 2004). The goal of a NEBA is to
determine which available response option(s) offers the greatest environmental
benefit compared with other response options, including natural recovery. Our
research will provide site-specific data to response managers so that they will be able
to estimate and compare relevant environmental risks and benefits associated with
various Arctic response options.
After 40 years of research, many international organizations have documented
evidence that the use of dispersants as an oil spill response can result in a lower
overall environmental impact than other techniques. Oil dispersants are spayed onto
an oil slick either by ship or aircraft in order to move the oil from the water’s surface
into the water column. Dispersants are made up of surfactant compounds containing
an oleophilic end attached to a hydrophilic tail. When applied to a film of oil, the
oleophilic end aligns with the oil phase while the hydrophilic tail extends into the
water phase. This reduces the interfacial surface tension between water and oil,
allowing the oil to become mixed into the top 5-10 meters of the water column as tiny
(1-70 µm) droplets (Lessard and Demarco, 2000). It is important to note that the
application of dispersants does not reduce the volume of oil in the environment, but
rather accelerates the movement of the oil from the surface to the water column.
During this process the chemical properties of the oil, and consequently the fate and
effects of the dispersed oil, will change (NRC, 2003). The efficiency of a dispersant
decreases over time as the oil weathers and emulsifies through the uptake of water
while losing its more volatile fractions to the atmosphere and as it begins to form
thicker residues of less bioavailable chemical mixtures. Although it is heavily
dependent on type of oil and weather conditions, modern dispersants are generally
assumed effective for at least 48 hours after a spill. In addition, recent research in
Norway presented by SINTEF indicates that dispersant effectiveness is longer in cold
waters and longer still in leads (water between ice floes) (SINTEF, 2009).
The toxicity of dispersants and dispersed oil is frequently questioned because
original dispersants included toxic chemical compounds (NRC, 1989). Efforts to
develop less toxic chemical countermeasures began in the late 1960s and today’s
dispersants are entirely different and far safer (Etkin, 1998). Advantages such as
lower-toxicity and more effective dispersant formulations have led to a gradual
expansion in the acceptance of dispersant use, particularly in the last 20 years. As of
today, dispersants licensed by the EPA are generally low toxicity compounds
(Lessard and Demarco, 2000).
The use of dispersants rapidly moves oil from the air/water interface into the
water column reducing the environmental impact of spilled oil on organisms that
reside or move through this layer (e.g., marine birds and mammals, surface dwelling
eggs, larvae and juveniles) and by preventing oil from impacting shorelines (Nordtug
and Johansen, 2007). As oil is dispersed into the water column, the ‘dissolved’
aquatic petroleum concentration increases and biodegradation can be significantly
accelerated (Lunel, 1998); (Swannell et al., 1997); (Lessard and Demarco, 2000).
The accelerated biodegradation of chemically dispersed oil is thought to be related to
the creation of smaller oil droplets, therefore increasing surface area available for
biodegradation by providing a substrate size suitable for bacterial colonization
(George-Ares and Clark, 2000).
In contrast to other spill responses, dispersants can be applied in harsh
weather conditions as long as vessels are able to reach the spill to dispense the
dispersants. Challenging weather conditions such as rough seas, strong winds and
currents can actually promote dispersant effectiveness by providing the required
mixing energy. While mechanical recovery is often preferred, it may be limited by
equipment availability as well as weather, and rarely results in recovery of more than
20% of spilled oil (Lessard and Demarco, 2000).
Research has shown that when a dispersant is applied to a controlled spill, the
immediate oil concentration in the water column can range from 2 to 180 ppm
(Belore et al., 2009); (Clark, 2008). Furthermore, at that same location after 2-5
hours, these concentrations were reduced to less than 1 ppm (Lessard and Demarco,
2000). This demonstrates that as the size of the plume increases, the dilution due to
dispersion reduces the concentration of petroleum over time. However, Swannell et
al., (1997) has determined that dispersed oil droplets persist in the water column for
days to weeks before they can be characterized as inert organic particles.
A workshop held in Anchorage in March 2008 facilitated discussions on the
effects of dispersed oil specific to the Beaufort and Chukchi Sea and provided the
basis for this current research (NewFields, 2008). The workshop was attended by
members of industry, government, scientific, and the North Slope Borough, Alaska,
communities. Several members of the scientific community presented information on
relevant areas of expertise such as: oceanographic features of the Beaufort and
Chukchi Sea, the fate and effects of dispersed oil (including wave tank testing),
marine communities native to the Beaufort Sea, international toxicity and
bioremediation research methods, as well as modeling distribution patterns of oil
spills. At the workshop, the toxicological effects of chemically dispersed oil versus
non-dispersed oil on key Arctic species and the establishment of biodegradation rates
using indigenous arctic microbial communities were identified as important
parameters for a NEBA model. It is necessary for the species selected for toxicity
testing to be sensitive to petroleum and dispersant compounds, of local ecological and
economic importance, and that they can be maintained in laboratory settings (Rand et
al., 1995). Potential candidate species for research activities were evaluated based on
these characteristics and additional information provided by the work group.
Following the workshop, a Joint Industry Program to Evaluate the Effects of
Dispersed Oil on Cold Water Environments of the Beaufort and Chukchi Seas (JIP)
was formed by ExxonMobil, Shell, and Statoil. The JIP research team felt that it was
imperative to use indigenous species from the Beaufort and Chukchi Sea in all testing
procedures. A number of toxicity studies involving dispersed oil have been
performed at various conditions, but typically with temperate species. Limited data
exists regarding the effects of dispersed oil in the key components of the Beaufort and
Chukchi Sea food web. The proceedings of this workshop identified two key Arctic
species that were primarily chosen based on their location in the pelagic food web:
Calanus glacialis (copepod) and Boreogadus saida (Arctic cod). Testing protocols
were also discussed and formed the basis of the current experimental procedures.
2
Objective
This research encompasses an in-depth project to determine the toxic effects
and biodegradation rates of dispersed oil under Arctic open water conditions. The
two main objectives of this study are to: 1) determine the toxicity of dispersed Alaska
North Slope (ANS) crude oil to indigenous copepods (Calanus glacialis) and Arctic
cod (Boreogadus saida) compared to non-dispersed oil and to further compare those
results to temperate species, and 2) determine the biodegradation rates of dispersed
oil compared to non-dispersed oil. These technical data would then be used to help
optimize response options in order to minimize negative ecological effects.
Another important objective of this JIP research is to mimic natural Arctic
conditions in the laboratory as much as possible. All water used in this study was
fresh seawater collected from the surrounding Beaufort and Chukchi Seas. When
collecting indigenous test species, environmental parameters such as temperature,
dissolved oxygen, salinity, pH and light intensities are measured and mimicked in the
laboratory.
3
The Barrow Laboratory Facility
The laboratory and cold room testing space is leased from the Barrow Arctic
Sciences Consortium (BASC) located in Barrow, Alaska. The building and the land is
managed by the Ukpeaġvik Iñupiat Corporation (UIC). The laboratory is situated in
the Barrow Arctic Research Center (BARC), which is a new facility located on land
that was part of the old Naval Arctic Research Laboratory (NARL). Staff from the
University of Alaska Fairbanks (UAF) conduct the field and laboratory activities,
with oversight and support provided by NewFields Northwest LLC. All staff
conducting JIP research are required to become certified in cold climate safety
training and vertebrate animal care (IUAUC).
Since Barrow is not connected by road, all laboratory materials must be flown
or barged into this remote location. Some lab supplies classified as gas or liquid
hazardous materials are required to be shipped to Barrow by barge, creating time
management challenges. Two special items in the laboratory are a specialized
microscope for observing live organisms and a research grade respirometer. The
Olympus SZX7 stereomicroscope includes a digital camera and a temperature
regulated stage for identification of live copepods and other small animal species and
was provided by NewFields. A research grade respirometer was loaned to the project
by ExxonMobil and has been reassembled in the cold room.
4
Field Expeditions
All field activities are conducted in either the Chukchi or Beaufort Seas,
adjacent to Point Barrow. In relation to Point Barrow, the Chukchi Sea is to the
northwest and the Beaufort Sea is to the northeast. The Chukchi Sea is a shallow
(approximately 50 m deep) shelf located north of the Bering Strait and is
approximately 500 km wide (east-west) and approximately 800 km long (northsouth). It is fed from the south by nutrient-rich waters from the Pacific Ocean. The
surface area of Beaufort Sea is about 476,000 sq km and the average depth is 1,000
m. Extreme wind events often occur in the Chukchi and Beaufort Sea, with the
strongest winds occurring in winter. Surface currents are very responsive to wind
direction and have posed many challenges when collecting current driven species.
The JIP experienced the greatest success with copepods and juvenile cod when the
winds were blowing from the west. Unfortunately, a west wind, during ice cover
conditions, can be a sign of an Ivu, an “ice push” event when an ice sheet from the
sea overtops the shorefast ice, often at high speed. Our bear guards are especially
wary under these conditions and often leave the snowmobiles motors running and the
machines pointed to the east.
The 2009 field season (April – September) resulted in moderate collections of
juvenile Arctic cod (Boreogadus saida) and large abundances of copepods (Calanus
glacialis). It was necessary to pause our field activities in respect for fall and spring
whale harvest activities. The start of the whaling season is weather dependent and
whaling stops when a quota is met. Generally, spring whaling starts mid April and
fall whaling begins early October. The duration of either season can range from
approximately 20 to 50 days.
Working in both ice and open water conditions requires the development of
specialized sampling gear and techniques. With each winter field expedition, the JIP
was assisted by BASC bear and ice guards for safety. During winter field collections,
personnel traveled via snowmobiles to locations beyond the pressure ridge, about 1
km from shore. An ice auger was required to drill through the thick (approx. 1 to 2
m) ice to create a sampling port.
5
Winter Arctic Cod Collection
Our initial plan was to capture adult gravid cod and perform ex-situ
fertilization and perform toxicity testing with the larvae. We tried a variety of
techniques through the ice in January and February, using fishing gear and advice
from our guides and the Iñupiat community, including standard ice fishing “tip-ups”
with a 30-40 lb test line, split shot weights, and a variety of lures and bait. A tip-up is
a plastic, spring loaded, hook and line ice-fishing apparatus. We also had an “arctic
oven” tent with a special hole in its floor and tried another standard ice fishing
method, “jigging”. Weather and logistical issues hampered our efforts. Another
factor was the presence of the large grounded ice ridge west of Barrow. The height
made it difficult to cross to the far side where the open leads were located. When we
were able to cross the ridge we found copepods plentiful, but we were unsuccessful
collecting arctic cod until after the spring whaling season.
6
Summer Arctic Cod Collection
Fishing for juvenile cod resumed in September. Open water conditions
permitted the use of a several types of sampling apparatus ranging from a Sameoto
surface sampler to Bongo nets and small plankton nets (80-250 micron mesh). All
were equipped with a cod end collection chamber where the sample becomes
concentrated. The sampling apparatus attaches to a tow line (3-5 m), where it was
trolled behind a small boat for 2-7 minutes. The depth of the plankton net ranged
from approximately 2 m to just below the water’s surface. The juvenile Arctic cod
were commonly encountered with large numbers of small to large Cnidaria medusa
whose nematocysts caused undue stress on the captured cod. To minimize the impact
of this stress a woven mesh was added to the net bridles that deflected the medusa
away from the net. This permitted the smaller Arctic cod to enter the net where they
were captured and transferred to coolers to retain the cold capture temperatures and to
eliminate freezing. The fish collected at this time were successfully held for extended
periods in the laboratory prior to being used in the toxicity tests. Remaining fish were
euthanized according to IACUC procedures.
7
Winter/Summer Copepod Collection
A plankton net fitted with 80-250 micron mesh is lowered into the water
column and then pulled vertically back through the water column. The plankton net
is attached to a cod end where the sample is concentrated. Under winter conditions,
the plankton net is lowered down a hole drilled in the ice. Currents are strong enough
to pull the net into the water column. Once the drag line is fully extended (3-5 m),
the net is manually pulled up to the surface. Copepods captured during the winter
were primarily obtained at water depths of approximately20 meters. The same
plankton net deploying techniques are used in open water. The majority of copepods
captured during the summer were found near the surface of the water adjacent to
icebergs floating over water depths ranging from 20-30 m.
8
Culture Maintenance
All juvenile cod were collected and cared for according to procedures outlined
in the approved UAF Institutional Animal Car and Use Committee (IACUC)
assurance. Prior to collection, we filled 150 L Igloo coolers with ambient seawater.
Collected cod and copepods were immediately transferred to coolers containing
excess seawater for temporary storage. Coolers were transported to the lab and, since
the seawater varied somewhat in temperature while the cold room was held at a
constant temperature, the coolers were allowed to slowly acclimate to the cold room
temperature. Once acclimated, the organisms were transferred to aerated 10 gallon
aquariums containing 80% filtered (0.45 µm) seawater and 20% fresh non-filtered
seawater. Water quality parameters were measured daily and cultures containing
arctic cod were renewed (50%) with filtered (0.45 µm) seawater every other day,
while copepod cultures were renewed once a week. Collected copepods were used to
feed the arctic cod cultures, while copepods were fed 2 mL of 8-20 µm phytoplankton
suspension (Phytogold-M, Brightwell Aquatics, Catawiss, PA) every four days. Algal
growth was minimal due to the frequent renewals with low organic content seawater.
9
Respirometry
Manometric respirometry combined with GCMS total petroleum hydrocarbon
(TPH) analysis was used to evaluate biodegradation. Manometric respirometry was
chosen as the method to measure oxygen consumption in sealed flasks provided with
oxygen replacement, following a revised version of the Organization for Economic
Co-operation and Development (OECD) Guideline 301F. Respirometry enables us to
distinguish biological degradation of oil from chemical or physical losses. A Coordinated Environmental Services (CES) respirometer was loaned to the JIP Barrow
Lab by ExxonMobil Biomedical Sciences Inc. The closed system consists of twenty
electrolytic cells, CO2 traps, and 1L sample flasks, which are constantly stirring.
When a pressure difference is measured in the system, the electrolytic cell generates a
measurable amount of oxygen by passing an electrical charge between electrodes in a
copper sulfate solution. This oxygen is transferred to the sample flask, where the
microbes respire and convert the carbon in the solution to CO2. The CO2 is absorbed
in the sodium hydroxide trap, thus lowering the pressure and restarting the cycle.
The control unit of the respirometer is located outside the cold room while the
majority of the hardware and flasks is stationed inside the cold room. This permits
the respirometer to operate at lower temperatures than allowed with a temperature
controlled bath. The manufacturer traveled to Barrow and recalibrated the pressure
heads and verified that the unit was measuring oxygen consumption in the cold room
at -1°C. All 20 channels were calibrated to measure at inter-channel consistency of
+/- 2%.
The JIP will investigate the seasonal difference in biodegradation by
calculating biodegradation rates from measured oxygen consumption in different
seasons with the variation in light and water temperature. A fall 2009 biodegradation
study was designed to mimic fall water temperatures (2°C) and light durations (24
hour light). A winter 2010 study is currently underway and will run at -1°C in the
absence of light. All sample water used in the respirometer is collected within 24
hours of test initiation. Validation of biodegradation is performed at the end of each
test by measuring the concentrations of petroleum compounds via GC-MS and
comparing the final concentrations to the initial concentrations by relating the values
to the recalcitrant compound, hopane.
10
Community Outreach
An important part of the JIP work in Barrow is to interact with the local
Iñupiat community and learn their concerns and benefit from their traditional
knowledge of the arctic marine environment. This is a continuing interaction and
learning experience which was initially started by using the services of the locals for
guides and bear guards. The BASC staff is extremely environmentally
knowledgeable. In following their instructions and following the BASC safety rules,
our staff was reasonably safe despite very harsh conditions. To further local
interaction, we spoke at the local high school science classes, helped with science
projects, and participated in science lectures that were open to the public. We also
participated in the local pastime, Bingo, and continually interacted with locals and
sought their guidance on communication at multiple levels within the community.
11
Test Results
We completed several rounds of tests with the copepods, both standard
reference toxicity tests and tests with oil and dispersed oil, both fresh and weathered.
The copepods survived well in the cold room. The test protocol was an emulation of
the CROSERF testing (Aurand and Coelho, 2005) using a spiked exposure. Most
such tests are done with 96-hour exposures. We made assessments at the 96-hour test
period, consistent with most protocols, but then held the animals for up to two weeks
after the exposure to measure long term responses to spiked initial exposures
consistent with observations made by recent Norwegian experiments with Arctic
copepods (Melbye, 2008). Based on the survival of the controls and a consistent dose
response relationship between total oil and PAH concentrations the tests conducted
over the summer and into the winter were successful. The results are under review
and a scientific paper is being developed but they are not available for distribution at
this writing.
12
Future Research
Our research efforts on biodegradation and toxicity will continue into the
summer of 2010 and will then be prepared as technical reports, scientific papers and
dissertations. We anticipate that the majority of this work will be available during the
late summer or early fall of 2010. We also anticipate preparing several papers about
sampling methodologies and testing procedures that we have developed for this
programs as well as an interlaboratory comparison of test procedures and results with
another Arctic research laboratory.
13
Acknowledgments
We want to acknowledge the field and laboratory help of Kim Facker of UAF,
as well as the support of the BASC staff.
14
References
Aurand, D. and G. Coelho, (2005), Cooperative Aquatic Toxicity Testing of
Dispersed Oil and the “Chemical Response to Oil Spills: Ecological Effects Research
Forum (CROSERF).” Retrieved March, 2010 from http://www.ecosystemmanagement.net/assets/documents//FINAL%20CROSERF%20REPORT.pdf
Aurand, D. and C. G. Coelho, (2004), Net Environmental Benefit (Ecological Risk)
Assessment: Consensus Workshop. Retrieved March 2010 from
http://www.ecosystemmanagement.net/assets/documents//Upper%20Mississippi%20River%20ERA%20Fin
al%20Report.pdf
Aurand, D., L. Walko, and R. Pond, (2000), Developing Consensus Ecological Risk
Assessments. Retrieved March 2010 from http://www.ecosystemmanagement.net/assets/documents//CG%20ERA%20Guidebook.pdf
Belore, R.C., K. Trudel, J. Mullin, A. Guarino, "Large-scale Cold Water Dispersant
Effectiveness Experiments with Alaskan Crude Oils and Corexit 9500 and 9527
Dispersants", Marine Pollution Bulletin, 58:118-128, 2009.
Bird, K. J., R.R. Charpentier, D.L. Gautier, D.W. Houseknecht, T.R. Klett, J.K.
Pitman, T.E. Moore, C.J. Schenk, M.E. Tennyson, and C.J. Wandrey, (2008),
Circum-Arctic Resource Appraisal: Estimates of Undiscovered Oil and Gas North of
the Arctic Circle. Retrieved March 2010 from
http://energy.usgs.gov/flash/CARA_slideshow.swf
Buist, I., "In Situ Burning for Oil Spills in Ice-Covered Waters", Interspill, 2004.
Clark, J., "Fate of Dispersed Oil in Arctic Conditions", in Proceedings of the Effects
of Dispersed Oil: Emphasis on Cold Water Environments of the Beaufort and
Chukchi Seas Workshop, NewFields Northwest, Anchorage, AK, 2008.
Etkin, D.S., "Factors in the Dispersant Use Decision-Making Process: Historical
Overview and Look to the Future" in Twenty-First Arctic and Marine Oilspill
Program Technical Seminar, Environment Canada, 281-304, 1998.
George-Ares, A. and J. R. Clark, "Aquatic Toxicity of Two Corexit Dispersants",
Chemosphere, 40:897-906, 2000.
Lessard, R. R. and G. Demarco, "The Significance of Oil Spill Dispersants", Spill
Science & Technology Bulletin, 6(1):59-68, 2000.
Lunel, T., "The Sea Empress Spill: Dispersant Operations, Effectiveness and
Effectiveness Monitoring", in Proceedings of the Conference, Dispersant Use in
Alaska: a Technical Update, Anchorage, AK, 18-19 March, 1998.
Melbye, A., "Fate and Effects of Physically Dispersed Oil". in Proceedings of the
Effects of Dispersed Oil: Emphasis on Cold Water Environments of the Beaufort and
Chukchi Seas Workshop, NewFields Northwest, Anchorage, AK, 2008.
NewFields, "The Effects of Dispersed Oil: Emphasis on Cold Water Environments
of the Beaufort and Chukchi Seas", in Proceedings of the Effects of Dispersed Oil:
Emphasis on Cold Water Environments of the Beaufort and Chukchi Seas Workshop,
NewFields Northwest, Anchorage, AK, 2008.
NRC, "Using Oil Spill Dispersants on the Sea", Marine Board of the National
Research Council, The National Academy Press, Washington, D.C., 1989.
NRC, "Oil in the Sea III: Inputs, Fates, and Effects", The National Academy Press,
Washington, DC., 2003.
Rand, G. M., P. G. Wells, and L.S. McCarty, "Introduction to Aquatic Toxicology",
in Fundamentals of Aquatic Toxicology: Effects, Environmental Fate, and Risk
Assessment, 2nd ed., G. M. Rand (eds.), Taylor & Francis, Washington, DC, 3-66,
1995.
SINTEF, "Seminar on the JIP on Oil Spill Contingency for Arctic and Ice Covered
Waters", Anchorage, AK, 2009.
Swannell, R.P.J., F. Daniel, B.C. Croft, M.A. Engelhardt, S. Wilson, D.J. Mitchell,
and T. Lunel, "Influence of Physical and Chemical Dispersion on the Biodegradation
of Oil under Simulated Marine Conditions", in Proceedings of the 20th Arctic and
Marine Oilspill Program Technical Seminar, Environment Canada, Vancouver, BC,
Canada, 617-641, 1997.
Nordtug, T. and Ø. Johansen, Effect of Dispersed Oil – Status of Knowledge, Criteria
for Establishment of Threshold Values and Recommendations for Further
Experimental Studies, Report SINTEF A3036, 2007.