Where We Live | The State of the Gulf: Where Has All the Oil Gone?

December 10, 2010


By Karen Pritchard

Flourish magazine | Fall 2010

In April of this year, an explosion occurred on British Petroleum’s Deep Water Horizon drilling platform, killing 11 workers and injuring many more. With this began three months of riveting television.

We watched in horror as the oil crept closer to the Louisiana wetlands. We sat riveted to the view of the gusher spewing toxic chemicals into the deep. Reporters followed the march of the oil along the Gulf beaches of Mississippi, Alabama, and Florida. We had daily updates of the failed attempts to cap the well, constant news reports of the economic hardships suffered by coastal communities, and devastating video of the brown pelicans so recently released from the endangered species list pitifully dragging around wings drenched in oil.

In April my friend Charles Gheen described the feeling of our Gulf Coast city: “We’re sitting here in Pensacola with much of the population feeling like they’re under the same Sword of Damocles as when a huge category five hurricane is careening around the Gulf of Mexico menacingly.”

Nightly on our news reports the oil was 10 miles, seven miles, three miles south of the beach. Then, in late June, two months after the initial explosion, oil came ashore on Pensacola Beach. I went to see it first hand. There were scores of people on the beach, but no one swimming, no one was digging sand castles, and no one was jumping in the surf. We looked like mourners at a funeral. Some people stood in silence, some walked around and poked the massive blobs of tar, and some wept openly. That was the last time I went to the beach last summer.

Then, seemingly miraculously in mid-July, the oil stopped gushing. BP managed to put a containment cap in place. It held. A tropical disturbance broke up much of the remaining oil and—hallelujah—the oil disappeared!

In early August, the federal government announced that 4.9 million barrels of oil had gushed from the deep ocean well. A small percentage was contained, but 4.1 million barrels had been unleashed in the Gulf of Mexico. The government estimated that half of the oil had either evaporated or been removed manually from the ocean surface, 25 percent had been dispersed or removed by natural processes, and 25 percent was onshore or buried in the deep ocean.

And with that, the country moved on. No more live feed of oil spewing into the ocean’s depths, no more video of oil floating on the surface, and no reason to stay glued to your television. Mission Accomplished.

Famous last words
Or was it? What actually happened to all that oil?

Government estimates of the oil’s evaporation are fairly accurate. Crude oil is a mixture of different forms of hydrocarbons (organic compounds made entirely of hydrogen and carbon), and the type of oil typically produced in the Gulf of Mexico is called light sweet crude. Sweet means that it has a fairly low percentage of sulfur impurities. Light means that it has a higher percentage of lighter, more volatile hydrocarbons, which evaporate easily: Light crude can loose 75% of its starting mass in a few days. Its highly volatile hydrocarbons include some extremely toxic substances such as benzene, toluene, and xylene, but fortunately these evaporate quickly and tend not to accumulate in the food chain.

It is also likely that 25 percent of the oil was dispersed or removed naturally from the water. Many forms of bacteria consume hydrocarbons. In fact, remediation for the 1989 Exxon Valdez oil spill in Alaska included adding fertilizers to increase the growth of oil-consuming bacteria. But in the deep waters of the Gulf of Mexico, fertilization is unnecessary. Natural seeps of oil in deep Gulf waters release as much oil each year as was spilled by the Exxon Valdez incident. The bacteria in this region have developed along with these seeps and can devour oil at surprisingly fast rates.

Oil threatens the Gulf’s most fragile ecosystems
But this accounting still leaves 25 percent of the oil remaining. Seems minor? Not so fast. Twenty-five percent means over one million barrels of oil, more than was spilled by the Exxon Valdez. Although the volatile portions of this crude oil may have evaporated, heavier products have been left behind to sink to the ocean floor. Unfortunately this oil will degrade much more slowly and may affect the deepwater for years. Already core samples taken of deepwater sediment have found large deposits of crude to be devastating sediment fauna and flora.

Crude oil also remains near shore. Surface oiling is evident along the Louisiana shoreline, particularly within the sensitive marshes of Barataria Bay. The coastal wetlands and marshes of Louisiana are some of the most extensive in the United States. Fisheries associated with these habitats are responsible for 30 percent of the U.S. finfish and shellfish production each year. The wetlands also serve as critical nursery areas for most fish found in the Gulf of Mexico. Besides being a home to aquatic species, the wetlands also function as habitat for numerous coastal bird species and migrating waterfowl.

Even the beautiful Gulf Coast beaches are still under assault. Nearly 500 miles of Gulf beaches are still experiencing light to moderate oiling. This is not new crude coming ashore but rather tar, which was buried earlier in the season, coming onshore as small tar balls and tar mats. This tar is oil that has been buried underneath beach sands, where oil-digesting bacteria—because they require oxygen—can’t digest it, and it will remain there until it is mechanically removed—a process that was complicated by the presence of sea turtles that nest on the Gulf beaches this summer.

Still more tar remains buried in near shore sediments. Here in Pensacola, we thought our protective booms had prevented oil from entering our bay. Those hopes have been dashed by recent discoveries of oil buried in sediments inside Pensacola Bay.

Fortunately this oil is weathered and minimally toxic. Most of the damage from the remaining mixture of hydrocarbons will stem from oil that forms a sticky, tar-like substance and smothers living organisms. But even this weathered oil is not completely inert. Only the future will reveal what effects the residual compounds will have on the flora and fauna at the Gulf’s deepest points. While weathered, buried oil has a low probability of moving from water into living organisms, its effects could still range from carcinogenesis to immune system suppression.

The oil’s damage is done
So it is true that—apart from the lingering effects it leaves behind—most of the oil is gone. Does this mean we have dodged a huge oil-dripping bullet? Unfortunately, no. There are many unknowns about the effect the oil had on ecosystems while it was spilling. But here’s what we do know.

Many shrimp, blue crab, and finfish numbers have actually increased in the wake of the oil spill. This may seem surprising, but it is less a direct result of polluted waters than the oil spill’s effect on the Gulf fishing industry. Many of these populations, which have been over-harvested in the past, benefited from the release of harvesting pressure when the disaster closed fisheries during what would have been heavy harvesting periods. But not all harvestable species were positively affected. The disaster severely impacted oyster harvesting in Louisiana, where tar mats have smothered large areas of oysters.

In an ironic twist, the primary impact on oysters and some other species seems to have resulted from efforts to protect the marshes from oil. In an attempt to flush oil away from Louisiana marshes, large quantities of freshwater were released directly into the marshes’ brackish water. Species that could not rapidly adapt to the freshwater dilution died.

The oil spill also damaged the Gulf’s delicate deepwater coral reefs. First discovered in the 1970’s, these deep reefs, found only in the Gulf of Mexico, are vital to over 70 different species of fish. Early inspection of these corals after the oil spill was encouraging. Corals found 20 miles away from the site of the spill looked healthy. However, further inspection closer to the oil spill has revealed large areas of corals smothered in oil, dying or already dead.

The Gulf of Mexico’s uncertain future
What we know about the biological impacts of the spill is dwarfed by what we don’t know. The real unknown is what will happen to future populations. Although it’s unlikely that toxic hydrocarbons will increase in concentration as they move up the Gulf food chain, we don’t know what disruptions to the interconnected aquatic populations have occurred until the larval organisms of those populations grow up.

Many species, like pink and brown shrimp, bluefin tuna, loggerhead sea turtles, and brown pelicans, were actively spawning or nesting during the oil spill. Many more were in sensitive larval forms when oil moved into the marshes. We already know that oil contaminated blue crab larvae. What effect will this have on the blue crab’s future? Will the larvae survive to adulthood? Will the adults be more susceptible to disease? Will the adults produced by these larvae even be able to spawn? We simply don’t know.

The future of those of us living along the Gulf is equally uncertain. For example, the menhaden fishery of the Gulf of Mexico is the third largest in the US. The menhaden is a fish prized for its high levels of healthy omega-3 oils. A crash in this population would be economically devastating to commercial fishing in the Gulf of Mexico. This population is being closely monitored due to fears that fish stock will collapse in a manner similar to that seen in Alaska after the Exxon Valdez spill.

A corner of God’s creation tarnished
Even now, thinking about the oil spill and the unknown future of the Gulf brings me to tears. Most residents in my town have lived in deep depression since the oil spill. Many have been harmed economically, many have been harmed psychologically, and still more have been harmed spiritually.

Normally I would have spent many summer afternoons hiking and kayaking along the Gulf islands. Instead I have stayed away from my beloved beaches. They have been tarnished, and I have lost the joy of exploring this area of God’s creation. The minute-by-minute hit television drama of the summer may have ended, but the Gulf still needs your prayers for healing. And so do we.

Karen Pritchard is an Instructor of Biology at the University of West Florida with a Ph.D. in Forest Resources specializing in Toxicology and Fish Pathology. When not teaching, Karen can be found running, hiking, or mucking around in her veggie garden. She is a companion to a dog, a cat, and four attack chickens.

{ 2 comments… read them below or add one }

Larry Oliver December 13, 2010 at 11:03 pm

Thank you so much for providing this comprehensive view of the state of the Gulf. It has been very hard to get a coherent picture of what has been happening from an objective view. Trying to integrate the hype, counter-hype, noise, and deafening silence from various parts of the media has made it difficult to understand what’s really happening.

If you have any insight into articles like this, http://english.aljazeera.net/indepth/2010/11/201011872121964396.html which come from world class journalists, I’d love to hear it… anything to settle the fog :)

Thanks in advance for any help or insight you can provide.


Larry Oliver
twitter: @tweetingdonal

Karen Pritchard December 14, 2010 at 12:46 pm

Hi Larry,

Thanks for your comment and concern about the issue of oil dispersants, in particular.

The use of dispersants was (and still is) a hot topic. Were they being used to “hide” the magnitude of the oil spill? Or were they being used to honestly reduce the environmental effects? We may never know. But we do know that they made oil products that normally would not mix readily with water do so more effectively (think salad dressing – sometimes oil and water do mix, temporarily).

What would this do to various crude oil fractions within the water column – the only comment I can make is that it would increase the availability to oil consuming bacteria. What I don’t know is how it might affect the volatilization of the oil (particularly the light PAHs – polycyclic aromatic hydrocarbons) compared to simply allowing the crude to disperse naturally within the water column. However, a mixture of the oil and dispersants do not appear to be more directly toxic than the oil alone (http://www.epa.gov/bpspill).

The EPA also monitored air quality including PAHs along the Gulf Coast. PAHs are those very volatile compounds that are most directly toxic within crude oil.

So what to make of reports of individuals along the Gulf Coast with measurable levels of some of these compounds in their blood? This is very tough to answer. First, I want to make it very clear that I am not an expert in Human toxicology. I also have no research background in oil spills. Several of my colleagues at UWF are experts and many of them are involved in research associated with the spill. But I am not one of them.

Here are a couple of comments associated with these reports of PAHs and their metabolites measured in humans.

The problem I see is the elimination time of these volatile compounds from the body is very short. The half life of each of these metabolites is incredibly short – a couple of days at max. For people to be sustaining a body level – they would have to be chronically exposed. Which immediately brings up the question – what is the source of the chronic exposure? Is it the air along the Gulf Coast? From what I can see of air measurements of PAHs by the USEPA, this doesn’t seem incredibly likely. And of course, the highest measurements have been found directly along the Louisiana coast and most high during the highest periods of oiling. I’m just not sure what levels of exposure would lead to chronic body burdens, but it would have to be chronic exposure.

Could there be a water source? I’m not sure what the levels monitored elsewhere are but here in Pensacola, we just haven’t seen many days with any detectable levels of PAHs (also known as PNAs –polynuclear aromatics)

I have some friends going out on a research cruise next week to measure levels of PNAs in the deeper waters off Pensacola – I’ll let you know what they find

So yes, there are measurable levels in the air and some to a small degree in the water. But primarily nearer the actual spill site and the coastal regions of Louisiana that experienced the dominant impact. So I wouldn’t contest a report of body burdens with the oil spill as the culprit in someone who worked directly on the Louisiana coastal waters every day.

I absolutely believe that many of the cleanup workers were exposed to benzene and other volatiles at levels far above OSHA standards. But I have no real data to back up that belief. And I don’t believe that any attempt was made to blood test these individuals during the clean up process. But as I said in the article – these volatiles don’t build up in the body, they don’t bioaccumulate. And that’s due to the very short half life in the body. What we are going to see in these workers are the toxic effects of exposure.

As far as long term epidemiological work especially around Louisiana is concerned, it is going to be horribly complicated by the sheer volume of refinery operations and other industrial processes in the area. Plus smokers will be chronically exposed to PAHS such as benzene so that makes data interpretation that much more difficult. Smokers of a pack and half a day are typically exposed to 10x as much benzene as non-smokers each day, so you might expect to see a measurable amount in a smoker’s body. Does this mean they aren’t being exposed elsewhere – no, but it makes cause and effect much more difficult to prove.

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