A Plume of Gas and Public Interest

Deepwater Horizon oil spill:  24 May 2010, NASA image (photo from Wikimedia Commons, NASA Goddard Space Flight Center)

The Deepwater Horizon blowout left an oily taste in the mouths of a lot of environmental groups.  But the taste is worse when you add in the extent of hydrocarbon gas release.

A University of Georgia-led study co-authored by Florida State University oceanographer Ian MacDonald found that up to 500,000 tons of gaseous hydrocarbons were emitted into the deep ocean.  This generated concentrations of 75,000 times the norm and could result in zones of oxygen depletion as microbes degrade the gaseous hydrocarbons.

The amount of gas released by the blowout is critical for determining potential impacts on deep oceanic systems.  The depth of the blowout (nearly 1 mile) is significant because the hydrocarbon gases become trapped in the water column.

Then, microbes consume the gases which leads to low-oxygen waters.  And the timescale for replenishing oxygen is many decades.

It's difficult to separate oxygen depletion due to gas from that due to liquid hydrocarbons.  Therefore, documenting the total mass of discharged hydrocarbons is important for understanding the long-term implications for the Gulf's microbial communities and food chain.

The team calculated the gas discharge to be equivalent to 1.6 to 3.1 million barrels of oil.  This figure encompasses a lot of uncertainty, but even the lowest is a significant increase in total discharge.

Where exactly has all of the gas gone?  Also difficult to say, as the shifting small-scale currents in the Gulf have probably dissipated the plumes and the associated low oxygen zones.  And it will take a long time for the microbes to consume all the gases released:  they need other nutrients which are in scarce supply, and once these nutrients are depleted, the microbes won't be able to grow.

The opportunities for multi-disciplinary modeling of fluid dynamics and microbiology and economic and social effects are endless.

It's been nearly a year since the blowout.  The plume of upset and urgency seems to have diffused quite a bit since then; with stories like this cropping up reasonably frequently but without nearly the publicity that they would have had nearer to the event.  It might be interesting to model public interest in a particular disastrous event (I'd hate to call it a "natural disaster") as a source plume.  Now that's a PhD thesis waiting to happen.