DISCOVERY • UNDERSTANDING • ACTION
BP Deepwater Horizon Oil Budget:
The Fate of the Oil – Ocean Leadership Perspective
On August 4th the federal government issued a report (www.deepwaterhorizonresponse.com/
posted/2931/Oil_Budget_description_8_3_FINAL.844091.pdf) highlighting the components of a federal
oil budget calculator. The conclusions in this report summarize the government’s and BP’s conclusions
of the fate of the estimated 4.9 million barrels of oil that was spilled into the Gulf of Mexico from the BP
Deepwater Horizon oil spill. According to these federal estimates, approximately 25% of the oil has
evaporated or dissolved in the water; another 24% has been dispersed through natural or chemical
means; and another 25% has been removed from the marine environment through direct recovery from
the well head (17%), burned (5%) or skimmed (3%). That leaves 26% of the oil classified as residual
or still in the water column, marine sediments or washed ashore.
These findings have been widely reported, and federal officials have been quoted, as suggesting that
only one quarter of the oil remains in the marine environment and thus three quarters of the problem
is effectively “gone”. However, there are a number of assumptions and significant uncertainties that
need to be addressed through comprehensive sampling, monitoring and research before one can
accept this conclusion.
Certainly, the Gulf of Mexico contains natural (physical, chemical, and biological) mechanisms for
transforming, transporting, evaporating or diluting the myriad of chemical constituents in the oil.
However, even if you accept the assumptions in this new federal report, upwards of 1.3 million barrels
of oil remain in the Gulf, or the equivalent of five Exxon Valdez spills.
If one accepts the report’s assumption that 24% of the oil has been chemically or naturally dispersed
into smaller globules in the water column, the question of how much is biodegraded still needs
to be answered. How does the 1.8 million gallons of dispersant interact with the oil and effect the
biodegradation rates of the myriad of compounds in the oil as well as the transfer rates of these
compounds into marine organisms? In addition it is fair to assume that the 25% assigned to evaporation
and dissolution processes will not be all evaporation. Thus, how much of the oil dissolved in the water
is biodegraded and over what timescale? It is also reasonable to assume that a large proportion of
the 26% assigned as residual will remain in the water column or sediments. Thus, there is significant
research that needs to be accomplished before it can be assumed that only 25% of the oil remains
in the Gulf.
One should also recognize that the microbial biodegradation of the thousands of organic compounds in
oil favors the short chain hydrocarbons leaving behind the more toxic and often carcinogenic polycyclic
aromatic hydrocarbons. Thus, it is essential to consider the chemical composition of the myriad of
compounds resulting from the oil mixture over time and not just the amount of oil remaining in the water.
It is clear that we now need to establish a comprehensive long term research program in order to
understand the effects of the spill on the ecology of the Gulf. We need to observe the chemical,
biological and physical changes of the oil and its effects on the ecosystem from the wetlands to the
deep water sediments. This will require federal leadership at the highest levels to develop, implement,
and fund a coordinated, comprehensive and transparent science and monitoring initiative between
the academic, federal and industry scientific communities. The American public needs to understand
that this problem is not rapidly going away and based on previous oil spills, significant impact to the
Gulf environment, ecosystems and communities will continue for many years.
Dr. Robert B. Gagosian
President & CEO
Consortium for Ocean Leadership