Fate of bisphenol A and nonylphenol in the lake riparian zone: Distribution, transport, and microbial response

The lake riparian zone (LRZ) is a key area of material circulation between terrestrial and aquatic ecosystems. However, the exchange of endocrine disrupting compounds (EDCs) in this area is still unknown. Thus, in this study, the distribution, convection and microbial response of two typical EDCs, bisphenol A (BPA) and nonylphenol (NP), in submerged (SS) and temporarily flooded sediment (FS) of LRZ were investigated by in-situ diffusive gradients in thin films technology. Concentrations of BPA (11.07 +/- 2.49 mu g/kg) and NP (20.42 +/- 8.23 mu g/kg) in FS significantly fluctuated with depth, conversely, their concentrations in SS increased steadily with depth (BPA: 14.01 74.76 mu g/kg; NP: 14.14 137.01 mu g/kg). BPA and NP dynamics analysis based on the DIFS (DGT-induced fluxes in sediments) model and fugacity fraction showed the water-sediment exchange capacity of BPA and NP in SS was on average 2-3 times higher than in FS. Some bacterial genera involved in nitrogen metabolism can effectively transform BPA and NP, such as Pseudomonas, Novosphingobium, and Sphingomonas, which are more active in oxygenic FS than in hypoxic SS. Considering this evidence as well as an increasing EDCs pollution, the behavior and quantification of EDCs at the water-sediment interface of the LRZ merits a further investigation.