Decade-long historical shifts in legacy and emerging per- and polyfluoroalkyl substances (PFAS) in surface sediments of China's marginal seas: Ongoing production and ecological risks.

Since the addition of perfluorooctane sulfonate (PFOS) to the Stockholm Convention in 2009, it became imperative to reassess the distribution and ecological risk of per- and polyfluoroalkyl substances (PFAS) in coastal sediments over the past decade as sediment records the history of pollutants from human activities. To achieve this, sediments were collected in 2009 and 2021 from China's coastal regions. Despite the consistent geographical pattern where the highest concentrations of ∑PFAS were found in the Yellow Sea, temporal changes have emerged. During the studied period, ∑PFAS levels experienced an increase in the East China Sea while concurrently witnessing a decrease in the South China Sea. Of significance, emerging PFAS compounds displayed not only rising concentrations but also a broader array, pointing towards their intensified production and utilization within China. Alarmingly, PFOS levels in sediments taken from the East China Sea maintained a consistently high ecological risk status over the last ten years. Significant correlations were found between long-chain PFAS and organic carbon content. Comparisons between datasets from 2009 to 2021 uncovered a shifting ecological risk landscape, with heightened concerns for PFOA in the East China Sea, while PFOS-associated risks appeared to diminish in the South China Sea-potentially reflecting the transition to alternative PFAS chemicals. The research reinforces the importance of continuous monitoring and emphasizes the urgent necessity for deeper exploration into the environmental implications and hazards posed by emerging PFAS.