Determination of organic fluorinated compounds content in complex samples through combustion ion chromatography methods: a way to define a "Total Per- and Polyfluoroalkyl Substances (PFAS)" parameter?

Emerging contaminants are a growing concern for scientists and public authorities. The group of per-polyfluoroalkyl substances (PFAS), known as 'forever chemicals', in complex environmental liquid and solid matrices was analysed in this study. The development of global analytical methods based on combustion ion chromatography (CIC) is expected to provide accurate picture of the overall PFAS contamination level via the determination of extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF). The obtained results may be put into perspective with other methods such as targeted analyses (LC-MS/MS). The impact of pH, the presence of dissolved organic carbon and suspended particles on AOF measurements were explored. The effectiveness of the washing step to remove adsorbed inorganic fluorine (IF) has been proven for samples containing up to 8 mgF.L-1. CIC-based methods showed good repeatability and reproducibility for the complex matrices studied. Environmental applications of these methods have been tested. AOF and EOF analyses could explain between 1 % and 23 % and 0.1 % to 2 % of total organic fluorine (TOF), respectively. The sum of PFAS compounds expressed as fluorine could explain from 0.2 % to 11 % and from 0.003 % to 5 % for AOF and EOF, respectively. These results also suggest that some fluorinated compounds are not adsorbed or extractable and/or lost by volatilisation during the application of AOF and EOF analytical procedure. These findings highlight that AOF and EOF are not entirely efficient as proxy to assess "total PFAS" for assessing environmental contamination by PFAS. However, these methods could still be applied to gain a better understanding of the sources and fate of PFAS in the environment.

In-depth prospection of Avène Thermal Spring Water reveals an uncommon and stable microbial community

BACKGROUND

Avène Thermal Spring Water (TSW) exhibits therapeutic properties in the treatment of skin pathologies. Arising from a dolomitic aquifer system, its physico-chemical properties are well-established and its bacteriological quality regularly monitored. The microbiota of this aquifer have been characterized.

OBJECTIVES

We aimed to describe the structure of the bacterial community inhabiting the deep aquifer and to examine its dynamics over time.

METHODS

The Avène TSW was collected at the catchment point and filtered through 0.1 µm pore size filters. The sampling was carried out every 3 months to generate a 4-year time series. The DNA extracted from filters was analysed using high-throughput 16S rRNA gene amplicon sequencing, and the microorganisms and their contribution were characterized by the taxonomic assignment of sequence variants generated from each sample.

RESULTS

Bacteria were distributed into 39 phyla. Nitrospirae and Proteobacteria were the most prevalent, accounting for 38% and 23% of the total community on average, respectively. A stable pattern was observed throughout the study. A few bacterial species were always detected, forming a core community of likely chemolithoautotrophic organisms which might use energy sources and nutrients produced from water-bedrock interactions. Most of the species were distantly related to organisms described to date.

CONCLUSIONS

Avène TSW provided by the deep aquifer system harbours a unique microbial community, shaped by the physico-chemical characteristics of the deep environment. Its remarkable stability over time has revealed a high level of confinement of the water resource.

Hydrochemistry of Avène thermal waters (Avène-les-Bains, France)

Avène Thermal Spring Water (Avène TSW) has been used since 1743 in the treatment of various pathologies. The hydrothermal system is delimited by a reservoir mainly composed by dolomite and quartz in which meteoric waters infiltrate allowing rock-water interactions that control the water's chemical composition. Water analysis and geochemical calculations highlight that water composition is stable and low mineral salt content are controlled by natural geochemical equilibrium and the solubility of the minerals calcite, dolomite and quartz according to temperature and CO₂ pressure within the reservoir. In addition, the annual monitoring of surface waters sampled on the impluvium surface area confirms the absence of anthropic impact on water quality. The forest and the low human activity of the watershed contribute to preserve the natural groundwater quality. This confirms that nowadays, the recharge water is still of great quality for the future generation.

Metal availability in a highly contaminated, dredged-sediment disposal site: field measurements and geochemical modeling

Two complementary approaches were used to characterize arsenic and metal mobilizations from a dredged-sediment disposal site: a detailed field study combined with hydrogeochemical modeling. Contaminants in sediments were found to be mainly present as sulfides subject to oxidation. Secondary phases (carbonates, sulfates, (hydr)oxides) were also observed. Oxidative processes occurred at different rates depending on physicochemical conditions and contaminant contents in the sediment. Two distinct areas were identified on the site, each corresponding to a specific contaminant mobility behavior. In a reducing area, Fe and As were highly soluble and illustrated anoxic behavior. In well-oxygenated material, groundwater was highly contaminated in Zn, Cd and Pb. A third zone in which sediments and groundwater were less contaminated was also characterized. This study enabled us to prioritize remediation work, which should aim to limit infiltration and long-term environmental impact.

Factors controlling the growth of the Yoshida ascites tumour in the uterus of the rat

The growth of the Yoshida ascites sarcoma following transplantation into the uterine lumen of the rat is influenced by the reproductive state of the animal. The uterus of a rat showing normal oestrous cycles is resistant to the growth of the tumour, although viable tumour cells survive for as long as 5 days within the uterine lumen. The tumour grows readily within the uteri of animals inoculated in early pseudopregnancy.

The uterine epithelium is important in determining the resistance of the uterus to tumour growth, since damage to the endometrium, or inoculation directly into the endometrial stroma permits tumour growth within the uterus of the cycling animal.