Two new scientific reports raised fresh fears on Tuesday about the environmental fallout from the world's worst offshore oil spill and questioned government assurances that most of the oil from the ruptured well in the Gulf of Mexico was already gone. In one of the reports, researchers at the University of Georgia said about three-quarters of the oil from BP's blown-out Macondo well was still lurking below the surface of the Gulf... University of South Florida...oceanographer David Hollander said..."Dispersed does not mean that it won't have an impact"...