Are the Corexit 9500 oil disputants that BP is using on the massive Gulf spill causing excessive evaporation and black oily rain to fall in Louisiana?

This shocking video shows what appears to be the aftermath of oily rain, filmed in River Ridge -- just outside New Orleans. The filmmaker captures the clearly visible sheen in the gathering puddles, and describes the remaining substance as "thick" and "foamy," noting that it not only looks but also smells like the oil they witnessed the day before on Gulf beaches from the spill.

But can crude oil really evaporate?  The answer is yes, in fact in many of the early news broadcasts both government and BP officials said that the shoreline cleanup issues would be lessened due to normal evaporation. Expect those same experts to now deny that there is oil raining down on the Gulf states, but the facts will prove this is indeed happening.

According to a 2003 study titled "Oil in the Sea III: Inputs, Fates, and Effects" put out by Ocean Studies Board, Marine Board, and Transportation Research Board, oil behaves very differently when on the open water. The study states:

"Within a few days following a spill, light crude oils can lose up to 75 percent of their initial volume and medium crudes up to 40 percent. In contrast, heavy or residual oils will lose no more than 10 percent of their volume in the first few days following a spill. Most oil spill behavior models include evaporation as a process and as a factor in the output of the model."

As this diagram shows, 100% of gasoline evaporates within a few hours, and medium crude loses up to 40% of it's volume. The question is whether BPs Corexit 9500 oil disputants are accelerating the natural evaporation process. So the next time it rains in Louisiana, remember that you better not light a match!