In situ investigation of the depuration of fluoranthene adsorbed on the leaf surfaces of living mangrove seedlings

A novel approach for the in situ determination of fluoranthene (Fla) that was adsorbed onto the leaf surfaces of Avicennia marina (Am), Kandelia obovata (Ko), Bruguiera gymnorrhiza (Bg), and Aegiceras corniculatum (Ac) was established using laser-induced nanosecond time-resolved fluorescence (LITRF). The detection limits for the in situ determination of the Fla adsorbed onto the Am, Ko, Bg and Ac leaf surfaces were 0.03, 0.14, 0.16 and 0.31 ng spot−1, respectively. Using the LITRF method, the depuration of the adsorbed Fla from the leaf surfaces of the four selected mangrove species was investigated in situ. The results showed that the method was very simple and rapid to perform and it was applicable for a real-time in situ survey of the depuration processes of PAHs that were adsorbed onto the mangrove leaves. The depuration of Fla that was adsorbed onto the Am, Ko, Bg and Ac leaf surfaces followed fast and slow phases, both of which varied significantly between the mangrove species in terms of the elimination rate, the remaining Fla residues, and the effect of temperature on the remaining Fla residues on the leaf surfaces. Variations in leaf wax content and the leaf surface roughness among the four mangrove species were responsible for the differences in the rapid phase, while photolysis and penetration into the inner cuticle were dominant mechanisms for the slow depuration.