Tuesday, December 17, 2013


Hi! I'm CJ Beegle-Krause, a researcher at SINTEF, in Trondheim, Norway. I work with a large group of people working to better understand oil spills. Some people work on the chemistry and toxicity of oil, while my team works on computer modeling of the oil in order to answer many questions such as "Where does the oil go?", "How does the oil change in the environment?", and "What are the potential environmental impacts of the oil?" Additionally, we have some people working on how to clean up spilled oil. We  perform laboratory and open ocean field work with oil as well as develop computer models.

The picture above shows two types of spills: a leaking ship and a subsurface well. The oil will be located on the water surface and in the water column. Collecting oil with a towed boom and application of chemical dispersants from a helicopter are two response options shown in the picture, though there are more options such as in situ burning. Models can help responders evaluate different response measures as they formulate their plans. Winds and waves can disperse oil into the water column as droplets, and chemical dispersants also change the surface oil into smaller droplets in the water column.  In the DROPPS project we are working to improve modeling of the droplet related processes, particularly related to potentially applying chemical dispersants. A great deal of research goes into making a computer model appropriate for making decisions in real life situations.

For oil droplets, how small is small? Let's talk in terms of a human hair, which ranges in diameter from 17µm (pale blonde) to 181µm (black) (Thanks Wikipedia![1]). The lower end of this range is at the limit of what the human eye can perceive.

Oil droplets are small, but they are big news in understanding the movement and potential impacts of oil spills. The rise speed of an oil droplet is proportional to the droplet's diameter. Droplets that you can barely see will rise very slowly. Larger droplets, say millimeters in diameter, will rise more quickly, and can reach the ocean surface in a matter of hours from deep in the ocean. Smaller droplets take longer to rise, and very small droplets at ~10 µm in diameter are too small to rise, as they are trapped by friction with the water.
The mini Tower Basin
 

Why is something so small so important? The droplet size distribution determines how much of the oil will remain within the ocean, and how much will rise at the surface. During an oil spill, responders may have the option to add chemical dispersants to the spill, either from the surface or subsurface, to alter the droplet. Chemical dispersants break up oil into smaller droplets, so more of the oil stays within the water column. If a spill is in an area with many water birds, keeping as much oil as possible in the water column may be better, so chemical dispersants might be used immediately. On the other hand, if the spill is in a sensitive coral reef area, leaving the oil at the surface may be better, with cleanup using booms and skimmers to remove surface oil. In the US, response decisions are made jointly within the Unified Command, whose members include the U.S. Coast Guard, Trustee Federal and State Agencies, and the responsible party. They use output from computer models to evaluate the oil spill’s predicted path and any changes in the oil location from the potential use of chemical dispersants.

The Tower Basin


SINTEF has a new Tower Basin, which is 6 m high and 2 m wide: a big tank for making small droplets. We use it to simulate deepwater well blowouts. We do experiments to release different oil types under pressure through a small nozzle, and use different chemical dispersant ratios injected into the rising plume of oil droplets to change the droplet size distribution.

The modeling group works to put together the laboratory and field work with mathematical models in order to make predictions about where the oil will go in an oil spill, and how one might clean that oil up. We work on software called OSCAR (Oil Spill Contingency And Response) and DREAM (Does-related Risk and Effect Assessment Model). These models help people plan for and respond to oil spills.

Members of the Sintef modeling group





 
 

Tuesday, November 26, 2013


Hey everyone! My name is Liana Vaccari and I’m a PhD student in Chemical Engineering at the University of Pennsylvania. The research group I’m a part of has spent a lot of time understanding how things change at fluid interfaces, especially with microscopic particles. I took that know-how to look at the behavior of the oil-seawater interface when it is covered with a natural microparticle: bacteria. In the ocean, there are some bacteria that know when even small amounts of oil are present and they can feed on it. Encouraging them to eat the oil is a great way to get rid of this pollutant, but it’s definitely not that simple. Some bacteria species also form strong biofilms on various surfaces, and I’m studying the evolution of a biofilm that the bacteria, Pseudomonas sp., make between the oil and seawater. This could affect the way drops get broken up in the water column (something David talked about in his post in October) if the biofilms surround it.

David talked about using the crude oil from the Gulf of Mexico. The reason it’s so nasty is that there are all sorts of molecules that change the properties of interfaces, etc. Therefore, I’ve been using a very simple oil to get a good starting point in understanding what happens just with bacteria present. My experiments are also on a much smaller scale than David’s. The needle in the image below is only 1 millimeter across. For perspective, a millimeter is approximately the thickness of a credit card.

This picture is of an oil drop and an oil layer that I aged in the bacteria suspension for a day. Afterwards, I pressed the drop against the layer above and deformed it significantly, but it didn’t pop! I was surprised at how strong it was,
and decided to learn more about the formation of the film.
 
Basically, I have been tracking how things (bacteria and very tiny beads) behave at the oil-water interface when I let it sit for a couple of days. My main tool for these experiments is a microscope, where I record a huge amount of data.
 

 

Soon, I’ll be integrating my work with some of the larger scale projects. This will give us a more realistic view of what is happening in the ocean when these oil spills happen.

Wednesday, October 16, 2013


Howdy! My name is David Murphy, and I’m a postdoctoral fellow in Mechanical Engineering at Johns Hopkins University. I’m working with the other DROPPsters here at Hopkins (and across the world!) to study how oil spreads out in the ocean once it is spilled. It is important to understand how the oil breaks up into smaller and smaller blobs so that we can understand where it will eventually end up. Oil in the ocean can be dispersed due to many different environmental forces, such as currents, turbulence in the ocean, waves on the surface, and mixing created by swimming animals. Here at Hopkins we do experiments to simulate these mixing events in the laboratory so that we can better predict where the oil will go.
In this picture, you can see several of the tanks where we do experiments. The large tank on the right contains an oil/water mixture from one of my experiments.
In order to make our experiments as realistic as possible we are using real crude oil from the Gulf of Mexico. Crude oil is NASTY stuff! It is dangerous since it is flammable; it is also volatile, which means it gives off hazardous fumes. In order to keep us safe, we have a high-powered ventilation system to remove the fumes and fireproof cabinets where we store the oil. We also wear gloves to protect our skin.
The fireproof cabinet where we store the crude oil
Of course, once we have completed an experiment, we have to clean up. One of the things I’ve learned as a DROPPster is that oil is hard to clean up! It takes a lot of work to clean out our tanks after doing an experiment, and this makes me sympathize with the folks cleaning up oil on the beaches and in the marshes after a real oil spill. As we clean up in the lab, we can’t drain the oily water into the sewer, so we have a skimmer that separates the oil from the water. We can then collect the oil and dispose of it properly.

The skimmer and oil barrel where we collect oil after an experiment

Cleaning up after an experiment in our sink that drains to the skimmer
Finally, I want to give a little taste of what oil looks like when it is mixing with water. In the video below, oil that has been mixed with dispersant is leaking out of a nozzle to form a plume. This simulates oil rising from an oil well blowout on the bottom of the ocean. Like dish soap, dispersant reduces the interfacial tension between the water and the oil and allows the oil to break up into tiny droplets that will disperse in the ocean more easily. We’re studying how dispersant interacts with environmental flows to promote oil dispersal.


video

Monday, September 30, 2013


Hi! My name is Tracy Harvey and I am a master’s student at the University of Texas at Austin Marine Science Institute (UTMSI). Here at UTMSI, we are investigating the biological impacts of oil spills as part of the DROPPS (Dispersion Research on Oil: Physics and Plankton Studies) Consortium. I have been doing short-term incubation experiments exposing different species of protozoa, a group of unicellular organisms found in the ocean, to crude oil. Understanding protozoa responses to dispersed oil is important because they are a diverse group at or near the base of marine food webs.

One of the coolest species I have worked with is Noctiluca Scintillans (commonly known as 'sea sparkle'). N. Scintillans is a planktonic organism that gets its food by consuming other organisms. It is native to the Gulf of Mexico and is known for its bioluminescence along the coast during winter months, as seen in the picture below. Bioluminescence is the production and emission of light by a living organism and is often used as a defense against predators.

http://www.flickr.com/photos/mutolisp/8728146283/
In order to culture these guys we have to take plankton tows off the UTMSI research pier on incoming tides.


 As you can see, we end up catching a lot more than just N. Scintillans!


Because of N. Scintillans’ transparent balloon-shaped body it is easy to see what is going on internally. Compared to other protozoa cells, these cells are quite large. We are currently in the process of looking at N. Scintillans under the microscope to see if oil exposure changes its behavior. 

My next step is to look at the swimming behavior of other protozoa exposed to crude oil. Be sure to stay tuned to the DROPPS blog for more information on our research!