Taking another major step in sleuthing the 2010 Deepwater Horizon oil spill, a research team led by the Woods Hole Oceanographic Institution (WHOI) has determined what chemicals were contained in a deep, hydrocarbon-containing plume at least 22 miles long that WHOI scientists mapped and sampled last summer in the Gulf of Mexico, a residue of the Deepwater Horizon oil spill. Moreover, they have taken a big step in explaining why some chemicals, but not others, made their way into the plume.