Study on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) in the Excrement of Marphysa sanguinea

To clarify the degradation of polycyclic aromatic hydrocarbons (PAHs) in the environment, we measured the PAH concentration in fecal pellets excreted by the annelid, Marphysa sanguinea, in a tidal flat and investigated the time dependence of the concentration. The degradation of PAHs in the annelid's excrement approximately obeyed a pseudo first-order rate equation for initial 2 h. The half-lives of the PAHs were estimated to be 1.7-2.2 h. The cause of such rapid reduction in PAHs was discussed by taking into consideration the decomposition by enzymes and/or by microorganism in the excrement. Finally, the PAH reduction was ascribed to the transformation of PAHs into their derivatives by extracellular enzymes, produced by microorganisms in the excrement of M. sanguinea.