Figure 2: Total heterotrophic bacterial populations (cfu/g soil on YEPG plates) in lysimeters 1 through 6 at (A) the beginning of the field study and (B) approximately 14 years later demonstrated consistent groupings of population concentrations between lysimeters 1, 2, 4, and 6, which received a PAH challenge, and lysimeters 3 and 5, which did not receive a PAH challenge.