Enantioselective accumulation of chiral polychlorinated biphenyls in lotus plant (Nelumbonucifera spp.)

Abstract Enantioselective accumulation of chiral polychlorinated biphenyls (PCBs) 91, 95, 136, 149, 176 and 183 was investigated in lotus plants ( Nelumbonucifera spp.) exposed to these chemicals via spiked sediment, to determine uptake and possible biotransformation for aquatic phytoremediation purposes. The concentrations of most PCBs were greatest in roots at 60 d (19.6 ± 1.51–70.6 ± 6.14 μg kg −1 ), but were greatest in stems and leaves at 120 d (25.3 ± 6.14–95.5 ± 19.4 μg kg −1 and 17.4 ± 4.41–70.4 ± 10.4 μg kg −1 , respectively). Total amounts were greatest at 120 d and significantly higher in roots than those in stems and in leaves (1457 ± 220–5852 ± 735 ng, 237 ± 47.1–902 ± 184 ng and 202 ± 60.3–802 ± 90.2 ng, respectively), but represented less than 0.51% of the total mass of PCBs added to sediments, indicating that lotus plants were unlikely to remove appreciable amounts of PCBs from contaminated sediments. Racemic PCB residues in sediment indicate no enantioselective biodegradation by sedimentary microbial consortia over the entire experiment. Preferential accumulation of the (−)-enantiomers of PCBs 91, 95 and 136 were observed in roots, stems and leaves, but non-enantioselective accumulation was observed for PCBs 149, 176 and 183. These results indicate that aquatic plants can accumulate PCBs enantioselectively via root uptake, possibly by biotransformation within plant tissues as observed for terrestrial plants. This is also the first report to identify optical rotation of the atropisomers of PCBs 91 and 95.