Estimation of per- and poly-fluoroalkyl substances mass loads in the Danube River using passive sampling

Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River

The existing technologies in municipal wastewater treatment plants are ineffective in eliminating persistent fluorine-containing contaminants. At the same time, there is an increasing demand for novel organofluorine compounds, particularly in the production of lithium-ion batteries, as well as in the agrochemical and pharmaceutical sectors for more efficient ingredients. This implies that we must account for ongoing changes in the fluorine levels within riverine environments. To determine the fluorine concentration in the water phase of rivers, it is essential to measure both inorganic fluoride and total organofluorine concentrations. These analytes were measured in water samples collected monthly from twelve locations along the Hungarian section of the Danube River during the period from July to December 2023, applying ion-chromatography and combustion ion-chromatography. The concentration of inorganic fluoride ranged from 28 to 76 µg/L, with a median of 45.3 µg/L. The total adsorbable organofluorine concentrations were between 0.22 and 12.5 µg/L, with a median of 2.43 µg/L. To assess the impact of restrictions on the use of PFOA and PFOS compounds, these substances were quantified using a UHPLC-Q-TOF-MS system. A comparison of our data with previously published concentrations in the Danube River reveals a decreasing tendency, justifying the restricted use of these chemicals.

A POCIS-based approach for the monitoring of pharmaceuticals in wastewater treatment plants: Calibration and deployment challenges

The impact of pharmaceuticals in aquatic environments requires complementary monitoring techniques to the more conventional grab sampling approach for an improved sample representativity. This study explores the application of Polar Organic Chemical Integrative Samplers (POCIS) in the analysis of a wide range of pharmaceutical residues in wastewater effluent, highlighting its advantages over grab sampling. Passive sampling techniques, extending sampling duration several days or weeks, provide continuous and representative data, improving the punctual nature of grab sampling. Despite their advantages, achieving quantitative results remains a challenge. Calibration through precise determination of sampling rates (RS) is recommended to convert the accumulated contaminant mass on the adsorbent to water concentrations. In the present work, 78 pharmaceuticals were preselected for stability suitability for POCIS passive sampling. RS were experimentally determined for 49 stable compounds: 33 of them had not been previously reported and most the other 16 agree with previous published literature. These RS were used to determine the concentration of pharmaceuticals in a wastewater treatment plant (WWTP) near to Barcelona, Spain over 3 weeks. High concentrations of 1,7-dimethylxanthine (2897 ng L-1), 4-acetamidoantipyrine (191 ng L-1), acetaminophen (165 ng L-1) and rasagiline (152 ng L-1) were found. This study examines POCIS deployment strategies, calibration, and analysis methods for 49 pharmaceutical compounds in an WWTP effluent. This research establishes a robust methodology for quantitative passive sampling of pharmaceuticals in aquatic environments, providing critical insights for more accurate monitoring of pharmaceuticals of environmental concern.

Transport and dispersion of PFOA and PFOS in the Black Sea

A 3-D transport and dispersion model was applied to study the recent past and future dynamics of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) concentrations in the Black Sea for the 2016-2030 period. The modelled surface concentrations show a distinct seasonal behaviour, shaped by winter to spring convective mixing. A significant increasing long-term trend in PFOS concentrations is established, with concentrations in water layers 200 m below the surface increasing at 4-8% per year. Driving mechanisms for PFOA and PFOS transport and accumulation in the subsurface and deeper layers are the cooling of the surface water in winter and the transport of water masses from the North Western Shelf (NWS) of the Black Sea. A simulated 50% phase-out of PFOA and PFOS from 2020 to 2030 shows a 21% reduction in PFOA, while PFOS continues to increase.

The influence of climate changes on heavy metals accumulation in Alosa immaculata from the Danube River Basin

This research report provides a comprehensive overview of the historical trends in heavy metal concentrations in the Pontic shad (Alosa immaculata) populations from both the Danube River and the Black Sea, while also exploring the potential influence of global warming on metal accumulation. Through bibliometric modeling analysis, it reveals significant limitations in existing international research, particularly the lack of comprehensive data on the impact of hydroclimatic changes on heavy metal accumulation in Alosa immaculata. Recognizing the critical importance of studies on heavy metal bioaccumulation in Danube shad, this research underscores their significance in defining tolerance thresholds, quantifying the impact of toxic elements along the aquatic food chain, and enhancing the economic sustainability of ichthyofauna monitoring efforts. Furthermore, these studies contribute invaluable insights into the complex dynamics of aquatic ecosystems, offering essential decision-making support for optimizing commercial fishing management practices on the Danube and ensuring robust support systems for industrial fishing endeavors.

New PFASs Identified in AFFF Impacted Groundwater by Passive Sampling and Nontarget Analysis

Monitoring contamination from per- and polyfluoroalkyl substances (PFASs) in water systems impacted by aqueous film-forming foams (AFFFs) typically addresses a few known PFAS groups. Given the diversity of PFASs present in AFFFs, current analytical approaches do not comprehensively address the range of PFASs present in these systems. A suspect-screening and nontarget analysis (NTA) approach was developed and applied to identify novel PFASs in groundwater samples contaminated from historic AFFF use. A total of 88 PFASs were identified in both passive samplers and grab samples, and these were dominated by sulfonate derivatives and sulfonamide-derived precursors. Several ultrashort-chain (USC) PFASs (≤C3) were detected, 11 reported for the first time in Australian groundwater. Several transformation products were identified, including perfluoroalkane sulfonamides (FASAs) and perfluoroalkane sulfinates (PFASis). Two new PFASs were reported (((perfluorohexyl)sulfonyl)sulfamic acid; m/z 477.9068 and (E)-1,1,2,2,3,3,4,5,6,7,8,8,8-tridecafluorooct-6-ene-1-sulfonic acid; m/z 424.9482). This study highlights that several PFASs are overlooked using standard target analysis, and therefore, the potential risk from all PFASs present is likely to be underestimated.

Unregulated Active and Closed Textile Mills Represent a Significant Vector of PFAS Contamination into Coastal Rivers

Despite concerns over the ubiquity of per- and polyfluoroalkyl substances (PFAS), little is known about the diversity of input sources to surface waters and their seasonal dynamics. Frequent use of PFAS in textiles means both active and closed textile mills require evaluation as PFAS sources. We deployed passive samplers at seven sites in an urban river and estuary adjacent to textile mills in Southern Rhode Island (USA) over 12 months. We estimated monthly mass flows (g month-1) of perfluorohexanoic acid (PFHxA: 45±56), and perfluorooctanoic acid (PFOA: 30±45) from the upstream river influenced by an active mill. Average mass flows were 73-155% higher downstream, where historical textile waste lagoons contributed long chain perfluoroalkyl acids (PFAA). Mass flows of PFNA increased from 7.5 to 21 g month-1 between the upstream and downstream portions of the rivers. Distinct grouping of the two main PFAS sources, active textile mills and historical waste lagoons, were identified using principal components analysis. Neither suspect screening nor extractable organofluorine analysis revealed measurable PFAS were missing beyond the targeted compounds. This research demonstrates that both closed and active textile mills are important ongoing PFAS sources to freshwater and marine regions and should be further evaluated as a source category.

Occurrence and transport of novel and legacy poly- and perfluoroalkyl substances in coastal rivers along the Laizhou Bay, northern China

The pollution profiles of 25 legacy and emerging poly- and perfluoroalkyl substances (PFASs) in the estuaries along the Laizhou Bay, northern China were investigated to better understand the new structure of PFASs under international regulations and to estimate the mass loadings of PFASs in coastal rivers. About 39.87 kg/d of PFASs were discharged into the Laizhou Bay by the Xiaoqing, Mi and Zhimai Rivers. Total PFAS concentrations in the Xiaoqing River decreased notably in recent years, but were still greater than the levels in 2011. Contribution of replacement substances exhibited an increasing trend in recent years. However, the long-chain chemicals were still the larger contributors of PFASs. Perfluoromethoxypropionic acid (PFMPA) was first detected with high concentrations ranging from 165.3 to 586.3 ng/L in the Xiaoqing River. The results of this study provided baseline data for ecological risk assessment, environmental management and corresponding development of pollution treatment technology.