Yuxin Ma

Antarctic polynyas serve as natural laboratories for investigating the complex atmosphere-ocean-ice interactions and potential ecological risks of per- and polyfluoroalkyl substances (PFAS) in remote polar environments. This study presents the first comprehensive assessment of traditional and emerging PFAS in the Amundsen Sea Polynya (ASP) during the austral summer (December 2023 to January 2024), integrating their occurrence in seawater and biological samples with key hydrographic and biogeochemical parameters. Short-chain compounds, such as perfluorobutanoic acid (PFBA), exhibited nearshore enrichment driven by atmospheric deposition followed by summertime meltwater release. Continuous sea-ice formation and brine rejection within the ASP further promoted the expulsion of PFBA with brine and its accumulation in the underlying Winter Water layer. In contrast, long-chain compounds, particularly 6:2 fluorotelomer sulfonic acid (6:2 FTSA), were preferentially incorporated into sea ice and advected toward the ASP margin─typically the marginal ice zone (MIZ)─by strong offshore winds. Their subsequent release during late-summer melting, coincident with elevated colored dissolved organic matter (CDOM), resulted in enhanced 6:2 FTSA concentrations throughout the MIZ water column, possibly modulated by both microbial transformation and particle adsorption-settling processes. High bioaccumulation and biomagnification of 6:2 FTSA in Antarctic krill and Adélie penguins highlight its ecological risk to the Antarctic marine ecosystem. Furthermore, PFBA detection in Circumpolar Deep Water (CDW) suggests potential interbasin transport via the Meridional Overturning Circulation (MOC), implying that global mid- and deep-ocean waters may serve as a long-term reservoir for PFAS.

Traditional and emerging per- and polyfluoroalkyl substances (PFAS) are widespread in coastal environments influenced by intense anthropogenic activity. However, their spatiotemporal dynamics in response to seasonal oceanographic processes remains insufficiently understood. By integrating basic hydrological and biogeochemical data, this study systematically compares the occurrence and behavior of traditional and emerging PFAS in full-depth seawater and surface sediments across the coastal East China Sea (ECS) during summer and winter. Waterborne PFAS consistently exhibited nearshore-to-offshore decreasing gradients and surface enrichment in both seasons, highlighting persistent terrestrial inputs. Notably, summer concentrations were generally lower, with weaker negative correlations with salinity, likely due to enhanced freshwater discharge during the wet season, which diluted and dispersed PFAS more effectively. Seasonal reversal of coastal currents driven by the monsoon further modulated the contaminant transport pathways. In contrast, sediment PFAS concentrations were generally higher in the summer, which can be attributed to stronger vertical mixing in the winter that facilitates the remobilization of contaminants. Enhanced sediment resuspension during the winter also promoted greater partitioning of PFAS, especially hydrophilic short-chain compounds, into the aqueous phase. These findings offer valuable insights into the seasonal variability and environmental behavior of PFAS in coastal marine systems.

Traditional per- and polyfluoroalkyl substances (PFASs) have been observed in the remote Southern Ocean. In contrast, current knowledge about emerging PFASs, such as perfluoroether carboxylic acids (PFECAs), and their transport mechanisms remains ambiguous. In this study, the occurrence and transport of both traditional and emerging PFASs in the surface seawater of the Southeast Indian Ocean and Antarctic marginal seas are comprehensively discussed by integrating hydrological data. Long-chain PFASs were restricted to the north of the thermohaline front in the Southeast Indian Ocean, suggesting a transport barrier effect and the input of terrestrial contamination from low-latitude regions. Conversely, unexpectedly high levels of short-chain perfluorobutanoic acid (PFBA) were limited to the south of the Antarctic Circumpolar Current, preventing further northward transport. PFBA showed significant positive correlations with two emerging PFECAs, perfluoro-2-methoxyacetic acid (PFMOAA) and fluoro(heptafluoropropoxy)acetic acid (3:2 H-PFECA), which were also widely detected in Antarctic marginal seas for the first time. This suggests their similar sources and environmental behavior, as they were probably formerly accumulated in Antarctic snow through atmospheric deposition and released into seawater during the summertime melting process.

Polycyclic aromatic compounds (PACs), including harmful polycyclic aromatic hydrocarbons (PAHs) and more toxic derivatives, are continuously released contaminants. Their provenance and dynamics in coastal oceans remain poorly understood. This study presents the first comprehensive assessment of PACs in coastal oceans by combining their presence with key hydrological and biogeochemical indicators, and potential microbial degradation. High concentrations of Σ₉₂PACs (48-660 ng/L) were observed in the East China Sea, influenced vertically by upwelling and related sediment resuspension during winter. Spatial heterogeneity reveals distinct distribution patterns: PAHs and alkyl-PAHs were mainly influenced by riverine inputs, horizontal transport via coastal currents, and fronts acting as barriers, in contrast, oxygen-PAHs and nitro-PAHs were primarily shaped by secondary transformations within warm water masses rich in nutrients. The relationship between dissolved PACs and chlorophyll a underscores the dominance of biodegradation over the marginal biological pump effect during wintertime low primary productivity. Metagenomic analysis further highlights microbial degradation as a crucial PAC removal pathway, with enhanced microbial diversity driven by terrigenous advection and upwelling. The methodologies and findings of this research provide valuable insights into PAC cycling in coastal oceans.

Organophosphate esters (OPEs) have been observed in the remote Arctic Ocean, yet the influence of hydrodynamics and seasonal sea ice variations on the occurrence and transport of waterborne OPEs remains unclear. This study comprehensively examines OPEs in surface seawater of the central Arctic Ocean during the summer of 2020, integrating surface ocean current and sea ice concentration data. The results confirm significant spatiotemporal variations of the OPEs, with the total concentration of seven major OPEs averaging 780 ± 970 pg/L. Chlorinated OPEs, particularly tris(1-chloro-2-propyl) phosphate (TCPP), were dominant. The significant impact of hydrodynamics on the OPE transport is demonstrated by higher OPE concentrations in regions with strong surface currents, especially at the edge of the Beaufort Gyre and the confluence of the Beaufort Gyre and the Transpolar Drift. Furthermore, OPE levels were generally higher in drifting-ice-covered regions compared to ice-free regions, attributed to the volatilization of dissolved OPEs formerly trapped below the sea ice or newly released from melting snow and sea ice. Notably, TCPP decreased by only 19% in the ice-free area, while the more volatile triphenyl phosphate decreased by 63% compared with the partial ice region.

Estuarine and coastal environments are important transport pathways and regional sinks for anthropogenic pollutants. In this study, the occurrence and transport of the continuously released organophosphate esters (OPEs) was investigated together with physical and biochemical parameters throughout the water column in the Changjiang (Yangtze) River estuary during the summer. Total dissolved and particulate OPEs showed great spatial heterogeneity, with mean concentrations of 550 ± 280 ng/L in the estuary, 110 ± 270 ng/L in the front/upwelling zone, and 410 ± 450 ng/L in the continental shelf. OPE concentrations in the estuarine bottom waters were high due to massive terrestrial/sediment inputs. In contrast, the “surface enrichment and depth depletion” of OPEs in the continental shelf was closely related to seasonal stratification. Reduced OPE concentrations were observed in the frontal/upwelling zone due to isopycnal heaving. Frontal activity and upwelling induced phytoplankton blooms in the coastal regions, which jointly contributed to elevated OPEs beneath surface water with high phytoplankton aggregation. The OPEs mainly originated from wastewater treatment plant discharges, industrial pollution and consumer products. These OPEs generally posed a low ecological risk to aquatic lives, but their long‐term effects cannot be ignored due to their continuous high production, usage and release.