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Weird Facts About Oil and Oil Spills

NOAA Ocean Podcast: Episode 69

When it comes to oil spills and their impacts on marine environments, water and oil don’t mix. In this episode, we chat with an oil spill response expert, Doug Helton, regional operations supervisor for NOAA’s Office of Response and Restoration, Emergency Response Division, and discuss some weird facts about oil and oil contamination.

An oiled rock along the Mississippi River shoreline near New Orleans, Louisiana, following an April 2018 fuel oil spill.

An oiled rock along the Mississippi River shoreline near New Orleans, Louisiana, following an April 2018 fuel oil spill. Oil can come in different forms, including tarballs, pancakes, and mousse.


HOST: This is the NOAA Ocean Podcast. I’m Marissa Anderson. Today we're going to talk about oil, but we're not going to focus on what it is, or how it's used, or how it's related to climate change ... or any of the pros and cons of how we use this ancient fossil fuel. We're going to talk about what happens when oil spills into our coastal waterways. These spills, large and small, happen every day all around the world.

Oil spills can wreak havoc on ecosystems, with long-lasting damage to coastal plants and animals. And cleaning up these spills is harder and way more complicated than you think because once oil is spilled, it does some pretty weird stuff. And at NOAA, we have some of the world's top oil spill experts who provide scientific support to help deal with these spills in U.S. coastal waterways. Let's dive right into our discussion with Doug Helton, regional operations supervisor for NOAA’s Office of Response and Restoration, Emergency Response Division...

HOST: How many different types of oil are there?

HELTON: There's lots of different kinds of oils. There's two main classes, and that's crude oils and refined oils. Refined oils are the things that we put in cars and ships and airplanes.

Doug Helton, regional operations supervisor for NOAA’s Office of Response and Restoration, Emergency Response Division.

Doug Helton, regional operations supervisor for NOAA’s Office of Response and Restoration, Emergency Response Division.

So things like gasoline and diesel. Some ships use a very specialized, heavy fuel oil that's more like a roofing tar almost. So there's a whole range of refined oils, and then there's thousands of different kinds of crude oils. And some crude oils are very, very light, almost like a gasoline, and some are very heavy and come out of the ground almost like a tar — or in some cases, even almost like a solid material. So those can be very challenging to refine.

HOST: In your experience, are there typical types of oils that tend to make their way into waterways and the ocean?

HELTON: Yeah, the most common oils that are spilled are probably refined oils like diesel because they're used in so many different kinds of marine transportation — everything from pleasure boats, to tugboats, to freighters. So that's a very commonly spilled, commonly transported item. And then we see a lot of these medium-to-light crude oils that are produced in the Gulf of Mexico, like the same kind of material that was spilled during the Deepwater Horizon oil spill. So that's pretty common crude oil. So we see that fairly often, especially in Louisiana, Texas, and the Gulf Coast.

HOST: When these oils make their way into waterways or the ocean, do they typically float in the water or do they sink?

HELTON: Well, most oils float, but it depends a lot on the location where they're spilled. So most of the spills that we work on are in seawater, but occasionally we work on spills in freshwater and sometimes even in estuaries. So depending upon the density of the oil, that's the weight of the oil. Most of them will float, but if they're spilled in fresh water, some of them are close to the density of water and might be neutrally buoyant, and very few will sink when they're spilled. So those can be really challenging to deal with because most of the technology to clean up oil spills, things like oil booms and our floating barriers. So if the oil's not floating, then those barriers aren't gonna be very effective. I worked on a few spills in rivers where the oil might sink or be neutrally buoyant, and then it behaves almost like that oil you see in lava lamps, where it kind of bubbles around and is neutrally buoyant. And then as the currents carry the oil down river into more of a marine environment and more saltwater, then that oil might float once it reaches that saltwater environment, because the saltwater’s denser than freshwater.

HOST: When oils are in waterways or the ocean, how far of a distance can they travel on their own?

HELTON: As soon as oil is spilled, it starts doing a bunch of things. And one of them is that it starts to spread. And it's just like if you spilled, you know, a can of paint in your basement or milk on your kitchen counter, the first thing it's gonna do is just spread out. So that will happen almost instantaneously. And then once it starts to spread out, the environmental forces in the ocean, things like currents and winds, can start to carry it. We typically do a lot of modeling to figure out where the oil is going to go after an oil spill. And the general rule of thumb is that the wind is going to push the oil, but also the currents. And so the combination of winds and currents can move it dozens of miles a day, hundreds of miles over a week. So on a big spill, the oil could really move hundreds of miles from the source easily. So, and then it depends on if it's spilled into a place with really strong tidal currents. Like I live in Seattle in the Northwest, and we have a pretty big tide range every day in the Puget Sound. And some of the tide currents can be three or four, or up to 10 knots in some channels — so 10 miles an hour. And so if it's spilled in one of those kinds of locations, it could move very rapidly.

HOST: Do oils come in different colors?

HELTON: Like I said, once oil is spilled, it begins to change, and one of those changes is color. Part of that is that as the oil spreads, that layer of oil on the water gets thinner and thinner. So when you see, say, a leaking car on a rainy day, and there's a little bit of sheen on — an oil sheen on a puddle in the parking lot. That's typically what we call a rainbow sheen. It's a very, very thin layer of oil, and that refracts light, and so it looks like a rainbow as it gets thicker, it gets darker. If you see dark oil on the water typically means that it's thicker. It also depends on the kind of oil that was spilled in the first place. So some oils are naturally colorful and then some are artificially colored. Diesel is one that often has a red dye added to it. It's called red-dyed diesel — and it's dyed that color for taxation purposes. So that marine diesels and things that don't have to pay road taxes will be dyed red so they can't be sold in the automotive and road market. So if you see a red, a very bright red oil spill, it's probably a red-dyed diesel. There are some natural oils that are naturally colorful, and then over time as the oil degrades in the environment, it can change colors. You may remember after the Deepwater Horizon oil spill, there were pictures of oil coming ashore. That was kind of orangish and reddish, and that's because it starts to mix with water and become an emulsion or a mousse, kind of like mayonnaise. It gets whipped up by the waves and energy and will take on different colors.

HOST: You had previously mentioned how oil can take a mousse form. Could you describe a little more about the different forms that oils can take? I know there's some various terminology like mousse, pancakes, and tarballs.

HELTON: So there are a lot of different shapes and forms that oil can take. Mousse is one that is — we refer to it as an emulsion — so it's a mixture of oil and water. So once oil is spilled, if it's a calm day, it may just move slowly and slowly reach a shoreline and be picked up. If there's surf or a lot of wave energy, it can get turbulently mixed up and turn into this sort of emulsion that can be stable and last for a long time. Oil can also create these different kinds of tar mats and tarballs, and those are different shapes of oil as it degrades and why there's in the environment. So, initially, it might start out as a big continuous oil slick, but wave energy will break those into smaller and smaller chunks. And so the oil might start out as a big, dark slick, and then over the course of days, two weeks, turn into chunks of oil that can be the size of dinner plates to smaller and smaller pieces that we call tarballs. Those are more like a cookie or that size. And depending upon the things like if the oil comes ashore and mixes with sand, then it can have a lot of other material mixed into it. After a while, it can be hard to tell — is it oil, or is it just some sort of organic material — sandy, peaty soil, for example? Those tarballs can be very, very persistent, and people who live in the Gulf Coast may see them all the time from the natural sources that are out in the Gulf of Mexico. If you walk on the shoreline in Texas, or even in Southern California, it's really common to find these tarballs that are on the outside kind of weathered looking, almost like a charcoal briquette looking, but if you break it open, it might be gooey inside like a chocolate brownie. And that can stick to your clothes and your shoes and that kind of thing, pretty common.

HOST: So if oils, or say, those tarballs for instance — if they're not removed from the environment, and they're left there, how long would it take for them to degrade?

HELTON:The tarballs can be persistent for months and months, maybe years. And they're not all from accidental oil spills. A lot of those tarballs may be from natural seeps in the ocean. People may know about oil seeps, like the famous one in California is the La Brea Tar Pits. So these are places where oil seeps up to the surface of the land and makes a pool. In the ocean there are seeps, but instead of staying in a pool, it reaches the sea floor and slowly refloats and comes to the surface. And so those oil seeps are very, very common in places like Southern California and in the Gulf of Mexico. And that's why people are drilling for oil debtors, that there's these pools of oil. Some of those seeps are persistent enough that you can see them on satellites. And they might even be noted on a nautical chart that there's a natural seep there. Sometimes when there's an oil spill, you might see tarballs after a few weeks. But sometimes those tarballs are also just from those natural sources and will be always out there on the shoreline, but at some low level. There might be a tarball every couple meters, or a couple yards on a beach, might be a natural phenomenon, or it could be an indication that there's an oil spill that hasn't been reported.

HOST: Aside from those natural sources, where else do oils come from?

HELTON: Well,oil is a very big part of our economy and is used in all sorts of different ways. So anytime you store or transport oil, there's a risk of spills. There's lots of different kinds of ships that use oil. So a cargo ship, fishing boats, tugboats, all can have accidents and be sources. People think that oil tankers are a big source, but they're just one. Oil tankers like the Exxon Valdez carry a huge amount of oil, but they're relatively rare spills from those kinds of sources. Oil's also transported in barges and things like even cruise ships can carry millions of gallons of oil for their own use. Oil’s transported by pipelines, and sometimes those pipelines are in coastal areas, so if there's a break in the pipeline, it can spill into a waterway, into a river. Oil’s transported by railroads, so we work on rail accidents occasionally where a rail accident might put oil again into a river or body of water. There's oil production, so oil exploration, like offshore oil rigs like the Deepwater Horizon. There's thousands of those around our coastal waters, and they can have production accidents when they're exploring for oil; they can have accidents when they're producing oil; and then that oil, once it's extracted from the seafloor, goes into a network of pipelines that carry it to shore so there can be accidents along the way. You could have an event like a ship accident, a ship running aground, or a ship colliding with another one that could cause an oil spill. You could have a natural event like a hurricane that could disrupt an offshore oil terminal, offshore oil rig, and create a spill. So there's lots of different ways that oil can get into the water. One of the projects I've worked on has been looking at some historic shipwrecks. And most of the time when a ship sinks, it breaks apart and spills oil right then, but there are a number of wrecks in U.S. waters where the ship sank, and the oil stayed on the wreck, and then — over decades as that ship deteriorates on the seafloor — it starts to release oil.

HOST: In those instances where an older shipwreck starts to release the oil, what can be done to prevent more of a spill or contamination?

HELTON: There's some specialized tools to look at shipwrecks and try to remove oil from them. So sometimes if a modern event occurs, like say, a ship sank today, we would probably send down underwater remote-operated vehicles like little submarines that could go down and take a look at the wreck. There are some tools that can actually drill into the wreck and attach valves and pump the oil off. So we've done that in a few wrecks over the past few years. There was a wreck off of Long Island, New York, called the Coimbra that sank. The first few months of World War II, it was a tanker that was sunk by a German submarine and sat there for 70, 80 years until it started to leak. And a couple years ago, the Coast Guard and NOAA worked with other response organizations to mount an effort to tap into that wreck and pump the oil off.

HOST: Is it challenging to identify the source of a spill? Say if there’s a beach or a coastal area, and there are signs of an oil spill, say either a slick or tarballs, is it hard to try to find out where that came from?

HELTON:Yeah, identifying the source of oil can be a challenge. Sometimes it's obvious you have a big event like an oil rig on fire or a ship been distressed, and it's an obvious source. But there are times when we see oil in the water, and we don't know where it came from. And in the Gulf of Mexico, there are thousands of oil rigs. So the operators of those oil rigs are supposed to report if they have a spill, but they may not know that they had a spill or they may not report it. And then that oil drifts towards another offshore rig. And so there might be confusion about who the source is. There's thousands of miles of abandoned and derelict pipelines in the, especially in the Gulf of Mexico again, pipelines that were built, and the rig may have been removed, but the pipe, and the pipe hopefully was cleaned and, but sometimes those start to leak. So we've got a fair number of, what we call mystery spills and part of the challenge is, can we use our models and tools to identify where that oil might have come from? So we can predict where oil is going to go if there's an oil spill, but we can also kind of run those models in reverse and say if we found oil on this shoreline or this body of water, where might it have come from. Some oils are distinctive and we can tell them apart chemically, so if we can get a sample of the oil, we can do a match to a ship. So if a ship is carrying a specific high crude oil, we can take a sample from the ship, a sample from the oil out on the shoreline and see if it chemically matches. But some oils are really commonly used like diesel fuel. So it'd be like if you found gasoline in a parking lot — which car did it come from? Well, all those cars have gasoline. They all have pretty similar gasoline. It's going to be hard to sort out which one it came from.

HOST: So if members of the public, if somebody happens to see a spill or what they think is a spill, are there any numbers or groups that folks should reach out to to report it?

HELTON: Yeah, if you see an oil spill or you think an oil spill is going on, there is a National Response Center that's staffed 24/7 and it's 1-800-424-8802. And that is the number to call and they will take their report and then pass that on to the local Coast Guard and EPA office that would be responsible for that area. That notification would also go out to other agencies like NOAA and Department of Interior and even go to tribes and other affected, potentially affected groups. So the National Response Center would also, on a significant spill, put out information about what's going on and may put out reports. That same number is the number that a shipper or a spiller would call and report it themselves. So hopefully they've already reported that oil spill, and the National Response Center will be happy to take an additional report from somebody observing it nearby, but they may already know about it.

HOST: This is the NOAA Ocean Podcast, thanks for joining us today. If you’d like to learn more about oil, be sure to check out our show notes. And make sure you subscribe to us in your podcast player of choice so you can dive in to all our episodes.