Degradation and Metabolism of Tetrabromobisphenol A (TBBPA) in Submerged Soil and Soil–Plant Systems

Abstract

Contamination by tetrabromobisphenol A (TBBPA), the most widely used brominated flame retardant, is a matter of environmental concern. Here, we investigated the fate and metabolites of (14)C-TBBPA in a submerged soil with an anoxic-oxic interface and planted or not with rice (Oryza sativa) and reed (Phragmites australis) seedlings. In unplanted soil, TBBPA dissipation (half-life 20.8 days) was accompanied by mineralization (11.5% of initial TBBPA) and the substantial formation (60.8%) of bound residues. Twelve metabolites (10 in unplanted soil and 7 in planted soil) were formed via four interconnected pathways: oxidative skeletal cleavage, O-methylation, type II ipso-substitution, and reductive debromination. The presence of the seedlings strongly reduced (14)C-TBBPA mineralization and bound-residue formation and stimulated debromination and O-methylation. Considerable radioactivity accumulated in rice (21.3%) and reed (33.1%) seedlings, mainly on or in the roots. While TBBPA dissipation was hardly affected by the rice seedlings, it was strongly enhanced by the reed seedlings, greatly reducing the half-life (11.4 days) and increasing monomethyl TBBPA formation (11.3%). The impact of the interconnected aerobic and anaerobic transformation of TBBPA and wetland plants on the profile and dynamics of the metabolites should be considered in phytoremediation strategies and environmental risk assessments of TBBPA in submerged soils.

A review of the environmental distribution, fate, and control of tetrabromobisphenol A released from sources

“…Reaction products include bisphenol A (BPA), and other intermediates that may be more persistent and toxic than TBBPA. O-methylation and debromination affect TBBPA occurrence in sediment and soil, where oxic and anoxic conditions may also lead to formation of BPA and mono-and dimethyl ethers Sun et al, 2014). TBBPA was observed to decrease with Gorga et al (2013) sediment depth in Lake Chaohu and the Pearl River Delta (Yang et al, 2012;He et al, 2013;Zhang et al, 2009b), which could result from degradation processes and increased usage in recent years.…”

Recent advances in the analysis of TBBPA/TBBPS, TBBPA/TBBPS derivatives and their transformation products

“…The transformation of 14 C-TBBPA in the soil and in the soil-plant system was investigated using GC-MS (Fig. 4A) [8,18]. Another complex exposure system was established that could be used to investigate the impact of interconnected aerobic and anaerobic transformations on TBBPA.…”

“…The application of calculation software could narrow the number of unknown candidates according to the consensus method. Strategies combining radioactive labeling, mass [17]; gray arrows indicate manganese dioxide exposed TBBPA, and GC-MS has been used [54]; red arrows indicate sunlight-catalyzed photolysis of TBBPA, and ion-trap-MS, FT-ICR-MS, and 1H (NMR) have been applied [16]; purple arrows indicate KMnO4-catalyzed degradation characterized by TBBPA, ESI-QqQ-MS [15]; black arrows indicate submerged anoxic-oxic interface and plant exposure, GC-MS [8]; light blue arrows indicate nitrifying activated sludge treatment on TBBPA analyzed using LC-ITMS [20]; orange arrows indicate biological transformation of TBBPA by Xenopus laevis and mammals based on LC-QqQ-MS and TOF-MS [56]. (B) Degradation of TBBPA derivatives predicted by UM-PPS.…”

“…The third group contains the transformation products of TBBPA/S and MTDs. For instance, TBBPA bis(methyl ether) (TBBPA BME) and TBBPA mono(methyl ether) (TBBPA MME) are the resultant transformation products of TBBPA via aerobic metabolism by bacteria [8]. Some products, such as TBBPA glucoside, could be formed as the result of biological transformation through the combination of TBBPA with biological molecules [9].…”

“…Cumulative evidence suggests that abiotic degradation, including photolysis, oxidation, reduction, and radical reactions, are involved in TBBPA degradation [14][15][16]. As compared with abiotic reactions, biotic reactions are considered to be the main transformation pathways of TBBPA and can result in the presence of unknown brominated substances in environmental compartments [8,17,18]. With the development of analytical methods based on MS, various transformation products of TBBPA have been observed [8,9,[15][16][17][18][19][20][21].…”