PARENT SESSION

1B+C Abiotic Transformation + Biodegradation
Hall 9
1:45 PM - 3:30 PM, Monday, 28 April 2003
Chair: Peijnenburg, W.¹, ¹
Co-chair: Jafvert, C.T.², Gombar, V.K.³, ^{2 3}

(MO9/15) Heterogeneous Photochemical Reactions of Decabromodiphenylether.

Jafvert, Chad¹, Hua, Inez¹, Bezares-Cruz, Juan¹, Filley, Timothy¹, ¹ Purdue University, West Lafayette, IN, USA

ABSTRACT- Annual volumetric production of polybrominated diphenyl ethers (PBDPEs) in 1999 was approximately 67,000 metric tons, with production of decabromodiphenylether (DBDPE) accounting for much of this tonnage. In contrast to other recalcitrant organohalogens, such as PCBs, whose concentrations are tending to decline in the environment, the concentrations of PBDPEs in the environment have been increasing over the past several decades. The predominant congeners found in wildlife (i.e., fish and mammal species) tend to be the tetra- and penta- congeners. The near absence of the specific congener, DBDPE, in these animals is thought to result from mass transfer limitations due to its extreme hydrophobicity and molecular size. Hence, the question arises as to whether environmental decay pathways of DBDPE lead to any of the lesser brominated congeners that are commonly found in organisms. One possible environmental fate process for DBDPE is photolytic transformation. Hence, in this research the photochemical reactions of DBDPE precipitated onto hydrated surfaces was investigated. Solar exposure of DBDPE precipitated onto quartz tubes and hydrated with water resulted in approximately a 50% loss after 72 hrs, although a bromine mass balance indicated that only about 50% of the total Br was accounted for after 72 hrs. It is likely that this low mass balance occurs due to polymerization of molecules within the precipitate during irradiation. In contrast, less than 10% of the DBDPE decayed when precipitated on humic acid (HA) coated silica particles, exposed to 96 hrs of solar irradiation. Despite the attenuation in rate, a greater increase in the HPLC intermediate/product peak areas was evident compared to samples in the absence of HA. A similar result occurred when HA was added directly to the aqueous phase.

Key words: solar irradiation, polybromodiphenylethers, reductive dehalogen, decabromodiphenylether