“Marine oil spill response is always evolving because everyone is trying to improve things.”
– Dr. Heather Dettman
Dr. Heather Dettman, a research scientist with Natural Resources Canada (NRCan), is considered a national and international expert on the fate and behaviour of petroleum products. During her time with NRCan, Dr. Dettman has developed expertise in the characterization of heavy oil and oil sands bitumen. She has applied this knowledge to specific research topics including refinery corrosion, petroleum upgrading and refining, bioprocessing and diesel fuel analysis.
Today, Dettman and her team at NRCan’s CanmetENERGY, Canada’s leading research and technology organization in the field of clean energy, have developed state of the art oil spill test facilities and are studying the behaviour of petroleum products including crude oil and heavy oils like diluted bitumen when spilled in water environments.
Tell us about a project you are currently working on.
At our lab we’ve built spill test facilities where we can study the behaviour of oil spilled in either fresh or salt water over a range of environmental conditions. Lab studies have included both fresh and salt water conditions. In the tanks, we are simulating oil that has reached shore and is being mixed with water and added sediment, in the surf. The tanks we use have adjustable wave and temperature conditions, and for one tank, the room temperature can be adjusted so that we can simulate both summer and winter air conditions. Our lab is unique in the extent of the test conditions and analyses we can do. As we change the conditions in the tank, we can follow how much of the oil evaporates, as well as how much of the oil floats, sinks or disperses into the water, and interacts with sediment.
We analyze the chemistry of the oil from the time that it enters the water environment. This allows us to follow the composition of the oil over time as it weathers. We’ve spent years testing different types of diluted bitumen products under different conditions. Diluted bitumen (dilbit), like conventional crude oil, is a mixture of oil types ranging from light to heavy oils. Bitumen has a lower content of light oil in it than conventional crude so needs extra light oil, called diluent added to it to make it ‘pipeline-able.’ It is not oil sands. Bitumen is the oil extracted from oil sands when the sand is removed.
To learn more about the test tank facilities, watch this CanmetENERGY video:
What are the objectives of the study?
At our facility, the primary goal of our work is to develop an understanding of petroleum, and particularly heavy oils like diluted bitumen. This understanding then allows for the design and optimization of technologies meant to minimize the environmental impacts of the production and refining of petroleum products.
Since 2012, we have been investigating how diluted bitumen and conventional crudes behave in water environments. It was then that we defined a research program at CanmetENERGY focused on oil spills. Our objectives then became to determine:
- How oil behaves under different environmental conditions;
- How that behaviour changes as you refine (or partially upgrade) the oils; and,
- How the toxicity of the oil changes as it weathers in different water environments.
What are the key messages of your research?
- Oil behaviour is complex and dependent upon the conditions of the spill.
- Higher viscosity oils, also known as heavy oils, do not mix into the water column as readily as low viscosity, light oils. The fluidity of low viscosity oils allows them to mix with water like cream mixes into coffee.
- If oil mixes with water, it can then interact with sediment. An interaction with sediment can then lead to the oil sinking. This is called sedimentation. Submerged oil can be problematic because it can have longer-term impacts.
- The behaviour of diluted bitumen is not unexpected or totally different from other petroleum products. Consequently, current spill response techniques for these oils can also be used when responding to diluted bitumen spills. We are finding that diluted bitumen floats for three weeks and beyond in the water environment conditions we have tested. Its tendency is to float.
- Diluted bitumen “absorbs” water. In a spill scenario, if diluted bitumen first enters freshwater in a river and then moves into saltwater it will be carrying fresh water and so will continue to float if it is already doing so. However, if it is spilled into salt water first, it will absorb the salt water. If the oil then moves into freshwater, or if it gets hit with rain which is also fresh water, then it could become submerged because the salt water it is carrying will make it more dense, or heavier, than the fresh water. This is important for responders to understand so they can prioritize preventing oil spilled in a marine environment from entering a freshwater environment.
- The toxicity of oil changes as it biodegrades in the water. Like other crude oils, diluted bitumen is most toxic when it initially enters the water and becomes less so as the lightest components of the oil either evaporate or are biodegraded.
When can we expect this project to be complete?
Our research is ongoing. Every year we accumulate more information and present snapshots of our results.
How do you anticipate your research being applied?
Every year we publish the results of our work and present at a technical seminar on environmental contamination and response organized by Environment and Climate Change Canada called AMOP. We are also beginning to publish our work in major academic journals.
We are collaborating with toxicologists to determine how toxicity changes with time after a spill. The toxicity results together with our chemical data are being used by graduate students to perform risk assessment analyses.
This work will also inform spill response and preparedness projects under Canada’s Oceans Protection Plan (OPP). So, the work that takes place in our chemistry lab is being applied for both policy development and in risk assessment by spill responders. It’s cool.
How is this research funded?
The funding for this research comes directly from the Government of Canada. Our most recent round of funding was announced last year as part of the OPP and it will support our work for the next four years.
What do you wish everyone knew about your research?
It’s not as simple as ‘does it sink or does it float.’ Oil’s behaviour is always dependent on environmental conditions.
We are developing more information so that spill responders can be better prepared to respond to spills of all oil types. Responders work with a wide range of oils and oil behaviours. No one can say oil is going to behave one way all the time, every time, because it’s not. What we are finding is that we don’t understand all triggers of an oil’s potential behaviour – for instance, for why conventional crudes can form a “chocolate mousse”-like texture during one spill scenario and not in the next. As well, when a crude oil “disappears”, is it all truly gone, or have parts of it just gone someplace else? We are working to add more information to fill these gaps and give responders a more complete understanding of petroleum behaviours.
What do you wish everyone knew about marine oil spill response?
Marine oil spill response is always evolving because everyone is trying to improve things. Oil spills are complex. Oil spill behaviour is complex and spill response really depends on environmental conditions and the knowledge people have. However, it’s not rocket science; people can learn the logic of it.
Spill responders are used to responding to oil spills of all types and response techniques have been developed and continue to be developed for the range of behaviours of all products transported across water environments. Responders know that diluted bitumen floats in the marine environment and that tools are currently available to recover diluted bitumen spills. But it’s not just about whether the oil sinks or floats. It’s not that simple.
What inspires you to do this work?
I want to understand why. Why is the oil behaving the way it is? Why might the toxicity be changing? Why? That’s my personal interest in it.
I was originally trained as a biochemist. In biochemistry, research is focused on determining the mechanisms for how and why things do what they do. So now that I am working with petroleum I ask:
- Why does one oil disperse, and what problems does it cause in which types of environments?
- Why does another oil not disperse, and what problems does it cause in which types of environments?
- Why does oil seeping into oceans naturally not appear to cause problems? Where does this crude oil go?
Where can we learn more?
You can learn more about Heather Dettman and her work on this episode of AskNRCan, Natural Resources Canada’s podcast, called “The science of diluted bitumen”:
Or by visiting the following sites:
More about Dr. Heather Dettman:
Dettman received her Ph.D. in Biochemistry from the University of Alberta. After completing a Natural Sciences and Engineering Research Council of Canada postdoctoral fellowship at Yale University, she was hired by the University of Ottawa to be manager of the Chemistry Department Nuclear Magnetic Resonance Spectroscopy Facility before joining NRCan in 1990.
#clearfacts #marinesafety #oilspill
Published September 20, 2018
Last modified on December 28, 2020