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John Kaba
7/12/10

Currently, my research is centered on the BP Deep Water Horizon well discharge.  Millions of gallons of crude oil have been pumped into the gulf and will affect northern gulf shores for years to come.  Small oil leaks the Gulf of Mexico are common, and there are microorganisms that readily degrade the oil fairly quickly, but can persist buried in beach sediments where oxygen and nutrients are limiting (Head et al. 2006).

John Seaguard

 


Primarily, I am looking into the fate of the oil once it reaches the shore.  Wave action and tidal pumping, both on diurnal and lunar cycles can move oil into the sediment.  Tar balls washing ashore are too large to penetrate the sediment, but under the hot Florida sun, some of the more volatile components can liquefy and permeate into the sediment.  This oil can be a huge problem to not only large animals like dolphins and pelicans, but also to plankton and interstitial beach fauna that migratory birds rely on.  Oil trapped in the sediment can also cause problems for ghost crabs and sea turtles when they dig into the beach.

Oil cores Currently I am testing changes in permeability, oxygen consumption/dissolved inorganic carbon (DIC) production, and microbial communities at beach sites before and after the oil has reached the shore, and the depth to which the oil penetrates the sand.  Samples have been taken from Daulphin Island, Alabama and St George Island and Pensacola, Florida.  Samples will also be run on a GC-MS to qualify and quantify hydrocarbons at various depths to monitor how the oil is degraded over time and which oil constituents are left in the sediment over a very long time.


Future oil experiments include observing penetration depth, oxygen consumption, DIC production, and degradation rates of tar balls, oil and oil with dispersant in sediment under varying conditions (oxygen, flow, temperature, light etc.).  Other possible experiments include chamber experiments with hydrocarbons labeled with stable isotopes to find out exactly which microbes are consuming the oil, and at what rates, both in oxic and anoxic conditions.

 

John diving

 


Previously, I worked with our post doc, Cedric Magen, on the degradation of dissolved organic carbon (DOC) in near shore sediments.  Several benthic stir chamber deployments were preformed to observe the degradation of DOC as it is moved through the sediment.  A large lab experiment was performed under very controlled conditions where DO13C was use to follow the degradation to DI13C by microbes under oxic and anoxic condition, both in sediment, highly filtered, and lightly filtered natural seawater.