TRANSFORMATION OF DECABROMODIPHENYL ETHER (BDE-209) IN A SOIL-SEDUM ALFREII SYSTEM AND THE EFFECT ON SOIL ENZYME AND ACYL-HOMOSERINE LACTONES

The transformation behavior of decabromodiphenyl ether (BDE-209) and its influence on soil enzymatic activities and acyl-homoserine lactones in a soil-Sedum alfredii system were investigated by a 60-day culture with BDE-209 treatments (0, 2.5, 5, 10, 15, and 20 mg kg(-1)). The dissipation of BDE-209 in rhizosphere soil (10.3%-33.4%) was higher than non-rhizosphere soil (4.4%-16.0%). The trend of polybrominated diphenyl ethers (PBDEs) was similar to the dissipation of BDE-209 (491.4-599.1 ng g(-1) in rhizosphere soil and 264.4-434.7 ng g(-1) in non-rhizosphere soil). Soil BDE-209 was taken up into the aboveground parts of S. alfredii. The BDE-209 concentration in plant tissues decreased in the order stem > root > leaf, except in the 20 mg kg(-1) treatment (root > stem > leaf). The lower-brominated PBDEs were preferentially accumulated in leaves (804.74, 789.76, and 576.24 ng g(-1) for leaves, roots, and stems, respectively) in the BDE-209 spiked groups. The activities of glucosidase, sulfatase, and nitrate reductase first decreased and then stabilized with BDE-209 increase. The dehydrogenase, urease, and alkaline phosphatase activities were significantly positively correlated with BDE-209 (p < 0.05). Three acylhomoserine lactone signals (C4-HSL, 3-oxo-C6, and 3-oxo-C12) were detected in rhizosphere soil and non-rhizosphere soil, of which C4-HSL was dominant. This suggests that S. alfredii could accelerate the migration and transformation of BDE-209 and C4-HSL was positively correlated with soil enzymatic activities and BDE-209 treatments.