In situ simultaneous investigation of the transport of phenanthrene and fluoranthene adsorbed onto the root surfaces to tissues of mangrove seedlings

Abstract

A novel method for the simultaneous in situ determination of phenanthrene (Phen) and fluoranthene (Fla) adsorbed onto mangrove root surfaces was established using laser-induced time-resolved nanosecond-fluorescence spectroscopy combined with a first-order derivative fluorometry (D-LITRF) method. The linear dynamic range, detection limit and recoveries of D-LITRF and laser induced time-resolved nanosecond fluorescence spectroscopy (LITRF) were of the same order. Using the established method, the transport of Phen and Fla from the mangrove root surface to tissues was simultaneously investigated in situ. The transportation coefficients of Phen and Fla adsorbed onto the root surface showed a good linear relationship with the content of root lipids, while the inhibition rates showed no significant correlation with the content of root lipids (p > 0.05). Further studies showed that the interaction between Fla and Phen decreased the transport kinetics, especially the slow and very slow transport kinetics. In addition, the coefficients and inhibition rates of the transport of Phen and Fla to Kandelia obovata (Ko) root tissues were evaluated at different temperatures. The results acquired by these in situ methods provide new information about how two PAHs components are transported from the mangrove root surface to the tissues.