Phytoremediation of PAH-contaminated sediments with different organic matter contents by Potamogeton crispus L.

In this study, phytoremediation of polycyclic aromatic hydrocarbon (PAH)-contaminated sediments with different contents of sediment organic matter (SOM) by Potamogeton crispus L. was investigated to find out the key factor controlling PAH dissipation enhancements. After a 36-day experiment, dissipation ratios of phenanthrene and pyrene in sediments were improved by P. crispus but decreased with increasing SOM content, no matter with or without P. crispus. Furthermore, the results of polyphenol oxidase activity and PAH bioavailability showed that they were both higher in planted treatments than in unplanted treatments. Finally, the enhancements of rapidly desorbing fraction (i.e., the main portion to be readily biodegradable) in sediments with SOM contents of 1.20%, 3.14%, and 5.08% by plants were 20.0%, 40.7%, and 66.7% for phenanthrene, 22.2%, 36.8%, and 58.8% for pyrene, respectively, which is consistent with the change trends of dissipation enhancements of the contaminants in sediments. However, there was no significant correlation between the enhancement of polyphenol oxidase activity and the dissipation enhancement. These results suggested that the improved bioavailability by P. crispus should be the key factor leading to the dissipation enhancements of the contaminants in sediments with different SOM contents, which provides essential information for phytoremediation of PAH-contaminated sediments.