"Non-limiting specific examples of superabsorbent polymers with differential swelling properties that are particularly useful in the method of the present invention include: a copolymer of acrylamide and sodium acrylate (TERRA-SORB GB, available from Industrial Services International, Inc., Bradenton, Fla.); hydrolyzed starch-polyacrylonitrile (TERRA-SORB available from Industrial Services Internat" . . . .