Sorption behavior of bisphenol A on marine sediments

摘要

Bisphenol A (BPA) is a known endocrine disrupting chemical (EDC) that has been widely used for the production of polycarbonate plastics and epoxy resins. In this experimental study, the sorption behavior of BPA on the marine sediments sampled from 6 different sites in the Mai Po Nature Reserve in Hong Kong was investigated. BPA sorption on the sediments can be well described by a linear sorption isotherm, suggesting a partition of BPA between the aqueous solution and the organic matter of the sediments. The BPA partition coefficient, K_d. for the raw sediment samples varied from 4.43 to 8.54 L/kg (R~2: 0.91-0.96) in nearly proportion to the organic content of the sediments. After the treatment of H_2O_2 oxidation for organic removal, the sediments had the K_d value reduced by more than 50%. However, the organic residue or black carbon of the sediments after the H_2O_2 treatment had a much greater sorption capacity than the natural organic matter on the sediment which was oxidized by H_2O_2. The organic normalized partition coefficients (K_(oc)) averaged around 1355 L/kg for the H_2O_2-treated sediment, which was more than three times greater than the K_(oc) value of 447 L/kg for the raw organic matter of the sediments. In addition to the organic content of the sediment, BPA sorption also was affected by a number of environmental factors. A pH drop, a temperature decrease and a reduction in salinity would increase the sorption of BPA on the sediment. The research findings are of significance to the description and assessment of the fate and transport of BPA and other similar EDCs in marine water-sediment systems.