This is a piece from the blog, "Gulf Oil Slick". In the article it describes how oil acts in water, how it rises to the surface, and how the chemical composition changes.
This is a very scary article.
http://bpoilslick.blogspot.com/2010/05/volcano-of-oil-erupting_14.htmlLink above is for the full story.
Some excerpts:
When An Oil Spill Originates on the Surface
Here is what happens when oil hits the salt water. If it is poured on top of the sea, oil begins to do several things. First some of it dissolves in the salt water. This dissolving is a bit limited but amounts to several percent per day of the spill exposure to the ocean. Some of the oil evaporates. This is several percent per day. This slows over time. As the oil dissolves and evaporates the parts that do this are primarily volatile fractions. These are things like Gasoline and other light components that go away pretty quickly. Once these are gone the remaining oil is heavy fraction crude. This begins to sink into the water very slowly, eventually falling to the ocean bottom over about 6 weeks. Typically this floats into an area where the shoreline is and embeds about 18 inches deep in the sand. This buried oil is not harmless. Just because the beach might appear on the surface to be clear, the sub-surface oil continues its toxic work. It locates precisely where the little sea creatures live, and it goes on killing them for about 10 years.
The reason a slick would carry farther than predicted is that the salt water is saturated with oil and the air around it is saturated, so the slick cannot dissipate. In the case of the BP Gulf leak, the size of the slick and the location of on shore oil say this slick represents at least 2 times the amount of oil BP estimated would never reach land -- or 330,000 barrels per day, minimum. This is an educated guess, borne out by aerial photos and the like.
And more....
When Oil Shoots Up Through 5000 Feet of Salt Water -- Fractionating Column
<snip>
Rising through 5000 feet of water, the oil is going through a process that the oil men call Fractionating. Literally the tremendous pressure and temperature issue are the equivalent of taking the oil and boiling it in a cracking tower 5000 feet high. The oil and Natural Gas change on their way up. The very light, easy-to-evaporate parts are all that is rising to the surface.
The heavy oil isn’t even getting to the top. That oil is losing its volatile fractions and is being dragged along with the rising column into the surface water where it is probably distributing as tar balls that are not being skimmed up or burned or otherwise dispersed.
In fact the chemicals added at the well head to disburse the oil, speed this process up. This oil is mixed into the water for the top 250 feet or so. Salinity and temperature issues probably keep this oil from ever reaching the very top of the water. The exact behavior here will not be known until studies are published some years from now. This is the first time humans have encountered a deep ocean leak of this magnitude. We're in uncharted territory here. Volume per volume, it is highly probable that due to this fractioning, this oil blowing into the ocean from a mile down is causing far more ecological trouble than a surface spill of similar size.
<snip>
Even if they suck up the oil on the surface, most will be underwater. But I guess outta sight, outta mind.
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