In situ monitoring the photolysis of fluoranthene adsorbed on mangrove leaves using fiber-optic fluorimetry.

A newly established fiber-optic fluorimetry was used to determine the fluoranthene (Fla) adsorbed on the leaf surfaces of three mangrove species, such as Excoecarla agallocha (Ea), Kandelia candel (Kc) and Aegiceras corniculatum (Ac). With the method, the photolysis of Fla adsorbed on Ea, Kc and Ac leaf surfaces was studied. Under the laboratory conditions, using a high pressure mercury lamp as light source, photolysis was found to be the main transformation pathway for the Fla adsorbed on the three mangrove leaves, whereas disappearance of the adsorbed Fla as a result of volatilization and absorption could be negligible. The photolysis of Fla adsorbed on the three mangrove leaf surfaces followed first-order kinetics with photolysis rates of Fla in the order of Ac > Ea > Kc. The photolysis half lives of Fla adsorbed on the leaves were from 14.32 min to 69.31 min. The different initial concentrations of Fla adsorbed on the selected mangrove leaves did not affect the photolysis rates of Fla. The absorption characteristics of leaf-wax played an important role to influence the different photolysis rates of Fla adsorbed on these three mangrove species.