Oil Presence May Speed Corrosion


The presence of oil in water is believed to increase the rate of corrosion on ships with steel hulls, according to a research project led by representatives from George Mason University and the Bureau of Ocean Energy Management (BOEM).

The findings of the project, launched in 2013, were presented at the Ocean Sciences Meeting of the American Geophysical Union Monday (Feb. 22), the association announced in a statement.

Corrosion and Microbiology Research

A multidisciplinary team of scientists embarked on its investigation in order to examine the effects the Deepwater Horizon oil spill and dispersant exposure had on the shipwrecks that lie on the Gulf of Mexico ocean floor, as well as the microbial communities forming the base of these ecosystems.

The Gulf of Mexico Shipwreck Corrosion, Hydrocarbon Exposure, Microbiology, and Archaeology (GOM-SCHEMA) project is the first of its kind to study deep-sea shipwreck microbiomes and the long-term impacts an oil spill has on shipwrecks and their microbial inhabitants, the researchers said.

“We are filling a huge void in our scientific understanding of the impacts of the spill,” said Leila Hamdan of George Mason University, who co-leads the project with Melanie Damour of BOEM.

Scientists found that the presence of a shipwreck itself can influence which microbes are present on the seafloor. In addition, the release of 4 million barrels of oil from the Macondo well for 87 days in 2010 further significantly altered nearby shipwreck microbial communities.

Even four years after the event, the team found, the oil and dispersants were still affecting the community structure and function of these microbes, potentially impacting other parts of the ecosystem.

Testing in Field and Lab Settings

The GOM-SCHEMA team conducted field and laboratory experiments to determine whether crude oil, dispersed oil and/or dispersant affected the community composition, metabolic function and/or corrosion potential of microorganisms inhabiting shipwrecks.

Carbon steel coupons (CSC) were placed at impacted and non-impacted shipwrecks or into four experimental microcosm tanks. After a two-week acclimation period, tanks were treated with crude oil and/or dispersant or received no treatment.

When CSC and seawater samples for bacterial genetic analysis were collected (biweekly from tanks and at 16 weeks for field samples), the team found that Proteobacteria dominated field and lab CSC bacterial communities at 77-97 percent of sequences.

The CSCs that were exposed to the oil and oil/dispersants exhibited higher corrosion compared to dispersant and control treatments, according to the researchers. These findings indicate that exposure to oil and/or dispersant may alter bacterial community composition and speed up corrosion of the steel-hulled shipwrecks.

According to Jennifer Salerno, a microbial ecologist at George Mason University, the oil may support a microecosystem for microbes that eat away at the metal or could trap metal-degrading hydrogen sulfide released by the microbes close to the metal, Science News said in its coverage. The oil and seawater mixture essentially doubled the amount of observed corrosion in the tests.

The team also used innovative 3-D laser and sonar technology to obtain high-resolution images of the vessels to document their current state of preservation.

“These are pieces of our collective human history down there and they are worth protecting,” said Damour, adding that in some cases these ships may still contain human remains.

“We are concerned that the degradation of these sites a lot faster than normal will cause the permanent loss of information that we can never get back.”

Long-Term Applications

The new findings show that deep-sea shipwrecks could be used for long-term monitoring of deep-sea ecosystems, according to the researchers. Understanding this unique ecosystem could aid in protecting and conserving it—both the animals that live on the shipwrecks and the ships themselves, they said.

Information about these shipwrecks could also aid scientists who research the deep sea and companies performing activities there, they added.

The GOM-SCHEMA project is part of the National Oceanographic Partnership Program sponsored by BOEM, the U.S. Naval Research Laboratory, the Bureau of Safety and Environmental Enforcement and George Mason University.


Tagged categories: Asia Pacific; Colleges and Universities; Corrosion; EMEA (Europe, Middle East and Africa); Environmental Control; Environmental Controls; Latin America; Marine; North America; Oil and Gas; Research

Join the Conversation:

Sign in to our community to add your comments.