Sorption of Polyfluoroalkyl Surfactants on Surface Soils: Effect of Molecular Structures, Soil Properties, and Solution Chemistry.

Zwitterionic, cationic, and anionic per- and polyfluoroalkyl substances (PFASs) are identified in aqueous film-forming foam (AFFF) concentrates and AFFF-impacted sites. However, the mobility potential of zwitterionic and cationic PFASs is poorly understood, preventing reliable site assessment. The study aimed to elucidate the mobility behaviors of PFASs of various charge states in saturated soil-water systems and assess critical influencing factors.

Zwitterionic, cationic, and anionic perfluoroalkyl and polyfluoroalkyl substances integrated into total oxidizable precursor assay of contaminated groundwater.

The total oxidizable precursor (TOP) assay can be useful for integrating precursors to perfluoroalkyl acids (pre-PFAAs) into the assessment of sites contaminated by per- and polyfluoroalkyl substances (PFAS). Current research gaps include risks of instrumental matrix effects due to the complexity of post-oxidation extracts, potential reproducibility issues during TOP itself, and limited information for zwitterionic and cationic pre-PFAAs. We first investigated a suitable method for the analysis of groundwater samples, using liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS).

Isomer-specific biotransformation of perfluoroalkyl sulfonamide compounds in aerobic soil.

As an important reservoir of pollutants, soil may play a critical role in altering isomer ratios of perfluorooctane sulfonate (PFOS) or PFOS precursors (PrePFOS) via microbial processes, but this possibility has not yet been investigated, as well as the feasibility of using PFOS isomer ratio for source tracking in PFOS contaminated sites. In the present study, N‑ethyl perfluorooctane sulfonamide ethanol (EtFOSE) of the technical grade was incubated in soil microcosms for 105 days to examine isomer-specific transformation processes. Experimental data combined with a mathematical model suggest new biotransformation pathways leading to PFOS, including a direct pathway to produce PFOS via hydrolysis of the sulfonamide bond.

Optimization of extraction methods for comprehensive profiling of perfluoroalkyl and polyfluoroalkyl substances in firefighting foam impacted soils.

The comprehensive analysis of aqueous film forming foam (AFFF) formulations has led in recent years to the discovery of novel classes of perfluoroalkyl and polyfluoroalkyl substances (PFASs). Whether the pre-existing analytical methods for historically monitored PFASs, including perfluorooctane sulfonate (PFOS), could be transferable to a large breadth of newly identified PFASs remains, however, an open question. Data from various lines of evidence indicate that current extraction procedures previously validated with anionic and neutral PFASs may seriously underperform for many cationic and zwitterionic PFASs.

Novel Fluoroalkylated Surfactants in Soils Following Firefighting Foam Deployment During the Lac-Mégantic Railway Accident.

The derailment of an unmanned train carrying crude oil and subsequent fire in the town of Lac-Mégantic, Quebec, led to the use of 33 000 L of aqueous film forming foam (AFFF) concentrate. While it is known that per- and polyfluoroalkyl substances (PFASs) contained in AFFFs pose a potential environmental and health risk, critical knowledge gaps remain as regards to their environmental fate after release. The accident in Lac-Mégantic provided valuable information regarding the identity and concentration of PFASs present in the soil after the AFFF deployment, as well as their possible transformation over time.

Assessment of the Influence of Soil Characteristics and Hydrocarbon Fuel Cocontamination on the Solvent Extraction of Perfluoroalkyl and Polyfluoroalkyl Substances.

Sites impacted by the use of aqueous film-forming foams (AFFFs) present elevated concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS). The characterization of the PFAS contamination at such sites may be greatly complicated by the presence of hydrocarbon cocontaminants and by the large variety of PFAS potentially present in AFFFs. In order to further a more comprehensive characterization of AFFF-contaminated soils, the solvent extraction of PFAS from soil was studied under different conditions.

Generation of Perfluoroalkyl Acids from Aerobic Biotransformation of Quaternary Ammonium Polyfluoroalkyl Surfactants.

The aerobic biotransformation over 180 days of two cationic quaternary ammonium compounds (QACs) with perfluoroalkyl chains was determined in soil microcosms, and biotransformation pathways were proposed. This is the first time that polyfluoroalkyl cationic surfactants used in aqueous film-forming foam (AFFF) formulations were studied for their environmental fate. The biotransformation of perfluorooctaneamido quaternary ammonium salt (PFOAAmS) was characterized by a DT50 value (time necessary to consume half of the initial mass) of 142 days and significant generation of perfluoroalkyl carboxylic acid (PFOA) at a yield of 30 mol % by day 180.

Production of PFOS from aerobic soil biotransformation of two perfluoroalkyl sulfonamide derivatives.

The continuous production and use in certain parts of the world of perfluoroalkyl sulfonamide derivatives that can degrade to perfluorooctane sulfonic acid (PFOS) has called for better understanding of the environmental fate of these PFOS precursors. Aerobic soil biotransformation of N-ethyl perfluorooctane sulfonamide (EtFOSA, also known as Sulfluramid) was quantitatively investigated in semi-closed soil microcosms over 182 d for the first time. The apparent soil half-life of EtFOSA was 13.

Microbial degradation of polyfluoroalkyl chemicals in the environment: a review.

Polyfluoroalkyl chemicals containing perfluoroalkyl moieties have been widely used in numerous industrial and commercial applications. Many polyfluoroalkyl chemicals are potential perfluoroalkyl acid (PFAA) precursors. When they are released to the environment, abiotic and microbial degradation of non-fluorinated functionalities, polyfluoroalkyl and perfluoroalkyl moieties can result in perfluoroalkyl carboxylic (PFCAs) and sulfonic acids (PFSAs), such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).