Phytoremediation of PAH-contaminated sediments by Potamogeton crispus L. with four plant densities

Abstract

In order to investigate the effect of plant density of Potamogeton crispus L. on the remediation of sediments contaminated by polycyclic aromatic hydrocarbons, a 54-day experiment with four plant densities(642, 1,604, 2,567 and 3,530 plants/m2)was conducted. The results showed higher plant density with slower plant growth rate. Surface area per plant was the most sensitive root parameter to plant density. At the end of the 54-day experiment, planting P. crispus enhanced the dissipation ratios of phenanthrene and pyrene in sediments by 6.5%—26.2% and 0.95%—13.6%, respectively. The dissipation increment increased with increasing plant density. Plant uptake accounted for only a small portion of the dissipation increments. Furthermore, P. crispus could evidently improve sediment redox potentials, and strong positive correlations between root surface area and the redox potential as well as between the redox potentials and the dissipation ratios of phenanthrene and pyrene were obtained, indicating that the oxygen released by the roots of P. crispus might be the main mechanism by which P. crispus enhanced the dissipation of PAHs in sediments.