Temporal Trends of Per- and Polyfluoroalkyl Substances (PFASs) in Tibetan Plateau Sediment Cores (1952–2020): Tracking Global Emission History and Industrial Transformation in PFAS Production

The Tibetan Plateau (TP), a critical sentinel for tracking long-range atmospheric transport (LRAT) of anthropogenic pollutants, provides indispensable archives for evaluating historical pollutant dynamics in pristine ecosystems. This study investigated temporal variations of 26 per- and polyfluoroalkyl substances (PFASs) in four alpine lake sediment cores across the TP spanning 1952-2020. Total PFAS concentrations ranged from 43.7 to 1428 pg g^-1 of dw. Linear regression of log-transformed PFAS concentration revealed a significant elevation-dependent trend across the studied lakes (<i>R</i>² = 0.58, <i>p</i> < 0.01) after excluding the lower-altitude, more human-impacted Qinghai Lake (3190 m), supporting mountain cold-trapping of these pollutants in high-altitude environments. Ranwu Lake demonstrated a unique PFAS profile dominated by perfluorobutanoic acid (PFBA), which contributed 48% of total PFASs on average, reflecting the predominant influence of glacier meltwater input pathways. The deposition flux exhibited an overall increasing trend, with fluctuations between 7.62 and 258 pg cm^-2 a^-1 during the studied period. Following a phase of relative stability or slight decline in the 1980s-1990s, all lakes showed a pronounced and sustained rise after 2000. Notably, the doubling time of short-chain PFBA (C₄) flux in these lakes was estimated to be 7.4-15.6 years since the post-2000 period. Compositional analysis revealed a global shift from long-chain to short-chain PFASs in TP lake sediments, as reflected by declining PFOS (C₈) and rapidly increasing levels of PFBA. The sedimentary record reveals temporal PFAS trends that closely track the historical evolution of global and regional PFAS emissions. Our findings provide crucial insights into the long-term trends of PFAS pollution in high-altitude ecosystems, contributing to global PFAS management efforts by assessing the effectiveness of regulations and the environmental impacts of industrial relocations.