title: Estimating stepwise debromination pathways of polybrominated diphenyl ethers with an analogue Markov Chain Monte Carlo algorithm.
abstract: A stochastic process was developed to simulate the stepwise debromination pathways for polybrominated diphenyl ethers (PBDEs). The stochastic process uses an analogue Markov Chain Monte Carlo (AMCMC) algorithm to generate PBDE debromination profiles. The acceptance or rejection of the randomly drawn stepwise debromination reactions was determined by a maximum likelihood function. The experimental observations at certain time points were used as target profiles; therefore, the stochastic processes are capable of presenting the effects of reaction conditions on the selection of debromination pathways. The application of the model is illustrated by adopting the experimental results of decabromodiphenyl ether (BDE209) in hexane exposed to sunlight. Inferences that were not obvious from experimental data were suggested by model simulations. For example, BDE206 has much higher accumulation at the first 30 min of sunlight exposure. By contrast, model simulation suggests that, BDE206 and BDE207 had comparable yields from BDE209. The reason for the higher BDE206 level is that BDE207 has the highest depletion in producing octa products. Compared to a previous version of the stochastic model based on stochastic reaction sequences (SRS), the AMCMC approach was determined to be more efficient and robust. Due to the feature of only requiring experimental observations as input, the AMCMC model is expected to be applicable to a wide range of PBDE debromination processes, e.g. microbial, photolytic, or joint effects in natural environments.
authors.affiliation: Department of Civil Engineering and Mechanics, University of Wisconsin - Milwaukee, Milwaukee, WI 53211, United States; Illinois Sustainable Technology Center, University of Illinois Urbana - Champaign, Champaign, IL 61820, United States. Electronic address: yhzou@illinois.edu.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Zou
authors.affiliation: Department of Civil Engineering and Mechanics, University of Wisconsin - Milwaukee, Milwaukee, WI 53211, United States.
authors.forename: Erik R
authors.initials: ER
authors.lastname: Christensen
authors.affiliation: Illinois Sustainable Technology Center, University of Illinois Urbana - Champaign, Champaign, IL 61820, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: School of Public Health, University of Illinois - Chicago, Chicago, IL 60612, United States.
authors.forename: Hua
authors.initials: H
authors.lastname: Wei
authors.affiliation: School of Public Health, University of Illinois - Chicago, Chicago, IL 60612, United States.
authors.forename: An
authors.initials: A
authors.lastname: Li
mesh_terms: D000465:Algorithms; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry*; D054879:Halogenation; D006586:Hexanes / Q000737:chemistry; D008390:Markov Chains; D008956:Models, Chemical; D010782:Photolysis; D013472:Sunlight
chemical_list: D055768:Halogenated Diphenyl Ethers; D006586:Hexanes; C026385:n-hexane; C512044:2,2',3,3',4,4',5,5',6-nonabromodiphenyl ether; C512045:2,2',3,3',4,4',5,6,6'-nonabromodiphenyl ether; C010902:decabromobiphenyl ether
keywords: Debromination pathways; Markov Chain Monte Carlo; Polybrominated diphenyl ethers; QSAR; Stochastic processes