Study On The Binding Of Polybrominated Diphenyl Ethers To Dissolved Organic Matter

Polybrominated diphenyl ethers (PBDEs) are widely used as additive brominated flame retardents (BFRs). PBDEs have been detected in lots of environmental and biota (including people) samples, and the level of PBDEs in the environment and biota presents obvious increasing trend. PBDEs have shown similar characteristics as persistent organic pollutants, such as long-distance transport, bioaccumulation. Tetra-, penta-, hexa-and hepta-BDEs are listed in the POPs by UNEP in May,2009.DOM (dissolved organic matter) is ubiquitous composition in environment, which was documented to be an important factor to affect the environmental behavior and ecological risk on a lot of pollutants (including heavy metals and organic pollutants). It was shown that DOM can increase the apparent solubility of hydrophobic organic compounds, change their bioavailability, enhance their transport and spread, thus increase their ecological risk. PBDEs show typical characteristics of hydrophobic organic compounds. Studying the interaction between DOM and PBDEs will be helpful to understand the environmental behaviors and to assess the ecological risk of PBDEs.In this study, equilibrium dialysis technique was used to determine the PBDEs-DOM partition coefficients (KDOC). PBDEs congeners (BDE-28, BDE-47, BDE-77, BDE-99,6-F-BDE-47, 5-MeO-BDE-47) and several kinds of DOM (Leonardite Humic Acid Standard, Aldrich Humic Acid, Elliott Soil Humic Acid Standard, and Suwannee River Fulvic Acid Standard) were applied. The influences of BDE congener, and DOM properties to the partition coefficients were examined.Results showed that DOM can significantly increase the apparent solubility of BDE congeners tested, and the enhancement was concentration-dependent for DOM. There is distinct difference on the binding ability for various DOM materials, and aromatic carbon in DOM molecular was inferred to be a key factor on the contribution of KDOC.Terrestrial DOM demonstrated stronger interaction with PBDEs than aquatic DOM. For tri-to penta-BDE congeners, the binding ability with DOM increase with Br number, and the substitution sites show significant influence on the KDOC coefficients. Other substitution function groups like F-, MeO-also showed some contributions. The KDOC obtained from single BDE congener exerted little difference from values gotten from the corresponding congener in penta-BDE technical mixtures, and the major trend between the congeners tested was quite similar. It was proved that DOM can notablly affect the behaviors and ecological risks of PBDEs, which worth further research efforts.