Benzo[a]pyrene (BaP) is a common environmental disrupting chemical that can cause endocrine disorders in organisms. However, the continued interference effects of BaP on multi-generation fish needs further research. In this study, we performed different periods (G1F1-3, G2F2-3, G3F3) of BaP exposure on marine medaka. We determined the embryo toxicity, and analyzed relative reproductive genes (ERα, cyp19a and vtg1) to predict the sexual differentiation of marine medaka. The results showed that high concentrations of BaP (200 μg·L⁻¹) significantly delayed the hatching time of embryos. Moreover, medium/high concentrations of BaP (20 and 200 μg·L⁻¹) prolonged the sexual maturity time of marine medaka. The relative gene expression of ERα, cyp19a and vtg1 were measured at 5 d_pf of embryos. We found that BaP had significantly inhibited the expression of the genes related to female fish development. Consequently, there were more males in the offspring sex ratio at BaP exposure. Overall, BaP can cause embryonic toxicity and abnormal sexual differentiation, while the expression of related reproductive genes can effectively indicate the sex ratio.

Sediment cores were collected from four outlets in the Pearl River Estuary (Guangdong Province, China) and dated using the ²¹⁰Pb method to investigate the pollution history of the area due to its relatively stable sedimentation status and hydrographic conditions in recent decades. The ages of the sediment cores were dated over 40 years (1968–2015). The concentrations at the four outlets ranged from 2.21 to 48.52 ng g⁻¹ dw for nonylphenol and were non-detectable for 23.64 ng g⁻¹ dw for bisphenol A (BPA), which exhibited a decreasing trend from north to south as well as seaward. The fluxes (2.84 to 112.91 ng cm⁻² yr⁻¹ and non-detectable to 59.33 ng cm⁻² yr⁻¹ for nonylphenol and bisphenol A, respectively) stabilized in the 1980s to 1990s due to the construction of sewage treatment systems. The fluxes increased again in the 21st century, which reached a peak ca. 2010 but declined in recent years due to the establishment of regulations and the decreasing number of industrial enterprises. Fluctuations in the pollution composition coincided with industrial development and governmental policies.