Environmental formation of sulfonated-PCBs and OH-sulfonated-PCBs: Is it greater under aerobic or anaerobic conditions?

The aerobic and anaerobic degradation of PCBs is well documented in literature. On the other hand, OH-sulfonated- and sulfonated-PCBs are newly discovered metabolites, therefore, little information is known about their fate in the environment. For instance, their formation in anaerobic conditions was never investigated. In the current paper, aerobic, anaerobic-aerobic (two steps mode) and anaerobic treatments were set up to compare for the first time the OH-, OH-sulfonated- and sulfonated-PCB production in different oxic and anoxic conditions. For this purpose, leaves of Quercus ilex were used as microbial inoculum in 40 mL vials spiked with PCB 155 used as individual contaminant. In general, all three classes were produced in every condition. The aerobic treatment was the best one, as the highest concentrations and number of congeners were detected. Then, the more oxygen decreases, the lower the concentration of metabolites formed: aerobiosis > anaerobiosis-aerobiosis > anaerobiosis. In addition, the same chlorination families for each class were formed, except for the anaerobiosis-aerobiosis treatment, where a hexa-Cl-sulfonated-PCB was also detected.