Skip to main content

Consequences of Deepwater Horizon oil spill

If you were able to stand on the bottom of the seafloor and look up, you would see flakes of falling organic material and biological debris cascading down the water column like snowflakes in a phenomenon known as marine snow.
Recent disasters like the Deepwater Horizon oil spill in the Gulf of Mexico, however, have added a new element to this natural process: oil.
During these events, the natural marine snow interacts with oil and dispersants to form what's known as marine oil snow as it sinks from the surface through water column to the seafloor sediments.
The danger with marine oil snow is that it transfers oil and its negative impacts from the water column to the sediments on the bottom of the seafloor, delivering a more diverse suite of oxygenated compounds to sediments and deep-sea ecosystems. These oxygenated forms of many oil compounds are more toxic to organisms in the sediments than are the non-oxygenated forms.
While this result may lessen the impact on near-surface organisms like fish and birds and shellfish, it transfers the oil to the deep ocean where it impacts fauna, deep corals, and fish down there, where adverse impacts were documented after the Deepwater Horizon oil spill.
The University of Delaware's Andrew Wozniak conducted research to investigate the fate and accumulation of marine oil snow in the Gulf of Mexico, the results of which were recently published in the Environmental Science and Technology journal.
Wozniak, assistant professor in the School of Marine Science and Policy in UD's College of Earth, Ocean and Environment, conducted the research while a research faculty member at Old Dominion University. He said that to recreate the conditions of the Gulf of Mexico, he and his collaborators used 100-liter glass tanks filled with seawater collected from the Gulf.
In addition to the seawater, they added plankton collected from coastal waters directly before the initiation of the experiment. They also added the kind of oil spilled during the Deepwater Horizon disaster, along with the chemical dispersant used to break it up, and monitored the tanks for four days.
Particles in the tanks formed on the surface, in the water column and the rest sank to the bottom. Wozniak collected the particles that sank and isolated the oil component to conduct a chemical analysis.
When they performed the chemical analysis and compared it to the initial oil, the samples differed in a way that could be attributed to microbial degradation.
Wozniak said this occurred as the marine oil snow sank through the water column.
When an event like an oil spill occurs, the phytoplankton and bacteria in the ocean interact with the oil -- which is bad for them -- and they release extracellular polymeric substances (EPS) which collects the oil.
"It's kind of a defense mechanism and because that EPS is sticky, it gets that oil aggregated and hopefully protects them from the oil," said Wozniak.
The result of the EPS protection is a base particle for other substances to glom onto.
"If something with enough density like minerals form on it, then they'll sink and that's when you get that marine oil snow," said Wozniak.
By looking at the degraded material at the bottom of the mesocosms, Wozniak could see that as the oil sank through the water column, it provided a microhabitat for microbes and microbes that prefer hydrocarbons and oil-like compounds proliferated.
In addition to supporting that community of bacteria, it also keeps a portion of oil that has been changed -- potentially for the worse -- in the ocean.
"It may have consequences for the toxicity of the oil because it oxygenates compounds," said Wozniak. "The oxygenated forms of some of the compounds, like Polycyclic Aromatic Hydrocarbons, tend to be more toxic and so it may have important implications for future study for what's happening in sediments or deep coral reefs."
The research was supported by a grant from the Gulf of Mexico Research Initiative to support consortium research entitled the Aggregation and Degradation of Dispersants and Oil by Microbial Exopolymers (ADDOMEx) Consortium.
Story Source:
Materials provided by University of Delaware. 
Note: Content may be edited.

Comments

Post a Comment

Popular posts from this blog

Major surgery associated with small, long term decline in brain functioning

Major surgery is associated with a small long-term decline in cognitive functioning -- equivalent, on average, to less than five months of natural brain ageing, finds a study in  The BMJ  today. But the odds of substantial cognitive decline also increase after surgery -- approximately doubling -- although the likelihood of this is much lower than after admission to hospital for a medical condition, the findings show. Cognitive decline is the gradual loss of brain functioning that occurs with ageing. It often starts decades before the conventional definition of old age and accelerates with ageing and the presence of an increasing number of underlying health conditions. Certain health issues, such as stroke, can lead to a large "step change" in cognitive decline, and there have been concerns that surgery might also do this, with some patients refusing beneficial surgical procedures as a result, say the researchers. Few previous studies have looked at the potential im...
Post a Comment
Read more

Dark matter may be older than the Big Bang

Dark matter, which researchers believe make up about 80% of the universe's mass, is one of the most elusive mysteries in modern physics. What exactly it is and how it came to be is a mystery, but a new Johns Hopkins University study now suggests that dark matter may have existed before the Big Bang. The study, published August 7 in  Physical Review Letters , presents a new idea of how dark matter was born and how to identify it with astronomical observations. "The study revealed a new connection between particle physics and astronomy. If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way. This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too," says Tommi Tenkanen, a postdoctoral fellow in Physics and Astronomy at the Johns Hopkins University and the study's author. While not much is known about its origins,...
Post a Comment
Read more

Scientists challenge notion of binary sexuality with naming of new plant species

A collaborative team of scientists from the US and Australia has named a new plant species from the remote Outback. Bucknell University biology postdoctoral fellow Angela McDonnell and professor Chris Martine led the description of the plant that had confounded field biologists for decades because of the unusual fluidity of its flower form. The discovery, published in the open access journal  PhytoKeys , offers a powerful example of the diversity of sexual forms found among plants. The new species of bush tomato discovered in remote Australia provides a compelling example of the fact that sexuality among Earth's living creatures is far more diverse -- and interesting -- than many people likely realize. Bucknell University postdoctoral fellow Angela McDonnell and biology professor Chris Martine led the study following an expedition last year to relocate populations of the new plant, which were first noted by Australian botanists during the 1970s. Herbarium specimens from th...
Post a Comment
Read more