Yulin Yan

Vertical distribution of archaeal communities associated with anaerobic degradation of pentabromodiphenyl ether (BDE-99) in river-based groundwater recharge with reclaimed water

When groundwater is recharged with reclaimed water, the presence of trace amounts of biorefractory pentabromodiphenyl ether (PBDE, specifically BDE-99) might cause potential groundwater pollution. A laboratory-scale column was designed to investigate the distribution of the community of archaea in this scenario and the associated anaerobic degradation of BDE-99. The concentration of BDE-99 decreased significantly as soil depth increased, and fluorescence in situ hybridization (FISH) analysis suggested that archaea exerted significant effects on the biodegradation of PBDE. Through 454 pyrosequencing of 16s rRNA genes, we found that the distribution and structure of the archaeal community associated with anaerobic degradation of BDE-99 in the river-based aquifer media changed significantly between different soil depths. The primary debrominated metabolites varied with changes in the vertically distributed archaeal community. The archaea in the surface layer were dominated by Methanomethylovorans, and the middle layer was mainly composed of Nitrososphaera. Nitrosopumilus and Nitrososphaera were equally abundant in the bottom layer. In addition, Methanomethylovorans abundance depended on the depth of soil, and the relative abundance of Nitrosopumilus increased with increasing depth, which was associated with the oxidation-reduction potential and the content of intermediate metabolites. We propose that Nitrososphaera and Nitrosopumilus might be the key archaeal taxa mediating the biodegradation of BDE-99.

Competitive sorption and desorption between BDE-47 and BDE-99 by different river- and farmland-based aquifer media

AbstractTwo main PBDEs that have potential endocrine disrupting properties—2,2,4,4′-tetrabromodiphenyl ether (BDE-47) and 2,2′,4,4′,5-tetrabromodiphenyl ether (BDE-99)—have been detected in environmental samples and have drawn public attention. In a single solute system, three aquifer media, Beijing river aquifer media, Beijing farmland soil, and Fujian farmland soil (FN), with different properties were collected as the main sorbents to investigate the sorption and desorption characteristic of BDE-47. The results indicate that a two-compartment first-order model could adequately describe the sorption kinetics of BDE-47. FN has the largest adsorption capacity, showing that a high organic matter content could improve the soil adsorption capability. In binary-solute systems, a series of BDE-99 with different concentration suppresses the sorption of BDE-47. The result indicates that the sorption capacity of BDE-47 significantly decreases with the increasing concentration of BDE-99, and the decreasing tendency...