Desorption from natural absorbents is an underlying process affecting the transport, chemical activity, and biodegradation of organic compounds in the environment. It is commonly understood that biodegradation of sorbed organic compounds involves at least two rate processes of desorption and biodegradation. These two rate processes, desorption and biodegradation, are both controlled by the concentration of organic compounds in liquid phase, thus the liquid-phase concentration of substrate is both the result of, and the driving force for, the two rate processes. In most natural environments, however, this situation may be further complicated by the interactions of the two processes. Previous studies mainly focused on the effects of desorption on biodegradation and bioavailability of organic contaminants, little is known about how the biodegradation process affects the desorption process. In the present study, twelve desorption systems derived from four adsorbents of two different types, prepared by treatments after adsorption equilibrium of phenol on agricultural soil and black carbon (BC), were used to investigate the desorption behavior of the phenol on the four adsorbents under the different bacterial densities of Pseudomonas putida ATCC 11172. The majority of phenol were adsorbed within the micropores of BC which was characterized to possess more micropore structures compared to the soil. All the sorption isotherms of phenol by the adsorbents were nonlinear, which were well fitted by Freundlich adsorption model. The results demonstrated that the biodegradation of phenol was rate-limited, depending on desorption rate of phenol from BC, while desorption was controlled by the biodegradation rate for the phenol sorbed on soil. The desorption data were fitted to a three-compartment model which divided the desorption into rapidly, slowly and very slowly desorbing compartments, and the respective parameters were calculated. As expected, desorption rate constants for three-compartment model followed the progression of rate constant of rapid desorption (r_q) > rate constant of slow desorption (r_s) > rate constant of very slow desorption (r_vs). Accompanied with cell density increasing in BC desorption systems, the rapidly desorbing fractions and slowly desorbing fractions increased by approximately 2-10 times, the very slowly desorbing fractions decreased by 40%-60%, and the rate constant of desorption for each fractions approximately maintain stable for the phenol adsorbed by BC. In contrast, for the phenol sorbed by soil, the three desorbing fractions did not change notably while the respective rate constant of desorption increased. These results indicated that the three desorbing fractions of phenol were related to surface structure of the adsorbents. For phenol sorbed on BC, the overall desorption was dominated by slowly and very slowly desorbing compartments and biodegradation rates were limited by desorption rates. Biodegradation could accelerate desorption rates of slowly and very slowly desorbing compartment of phenol on BC. For phenol sored on soil, however, the overall desorption was dominated by rapidly desorbing compartments, biodegradation rates were not limited by desorption rates and in turn could not affect each of the three desorbing compartments. In addition, the bioavailability of phenol in this study was related to the properties of microorganisms and absorbents. Microorganisms could not access the phenol sorbed in the micropores on BC due to the size of cell which was physically excluded from the micropores.