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Highlights • PFOS and PFOA levels are suggestive of levels of industrialization and poor environmental awareness. • Concentrations of PFOS and PFOA in porewater were greater than those in surface water. • Results of this study provided additional understanding of PFOS and PFOA partitioning between sediment and porewater. • Field – based fate and partitioning of PFOS and PFOA were highly dependent on salinity gradients. • Adsorption of PFOS and PFOA can be greater than expected due salinity changes in aquatic environment. Abstract Global concern on emerging pollutants such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are well documented. Unfortunately, information is either scarce or non-existing on the presence of these chemicals in most developing nations like Nigeria. The current study examined the distribution pattern and trend of PFOS and PFOA in surface water, porewater (PW) and sediments collected from three geopolitical zones with different levels of industrialization in Nigeria. PFOS and PFOA were concentrated using solid-phase extraction, identified and quantified by high performance liquid chromatography interfaced to a triple quadruple mass spectrometer. Detection of both PFOS and PFOA in all samples suggested wide distribution across Nigeria. Generally, PFOS dominated aqueous concentrations ranging from 3.9 to 10.1 ng L−1 in surface water, 10.9 to 20.4 ng L−1 in PW and 5.1 to 10.4 ng g−1 in bottom sediment. Field-based partition coefficients (K d) for both PFOS and PFOA were significantly correlated with salinity (r 2 = 0.84 and 0.78 respectively, p < 0.01); The K d values increased exponentially as a function of salinity. The enrichment of both PFOS and PFOA on sediment increased with increasing organic matter while in water with increasing salinity. The detection of these chemicals across all samples suggested urgent attention in their risk assessment. [ABSTRACT FROM AUTHOR]

Understanding sorption of PFOA on soil particles is crucial to evaluate its environmental risk. Here, sorption of PFOA onto ten agricultural soils was examined. The influence of soil physico-chemical properties on PFOA sorption was investigated. The sorption rate of PFOA followed a pseudo-second-order kinetics. Isotherm data of PFOA sorption was fitted with both Freundlich and linear models and the latter fitted better. The sorption-desorption of PFOA onto ten soil samples depended on soil organic carbon content and composition of soil minerals. The sorption and desorption isotherms of PFOA on ten soils were linear, except for the sorption of PFOA onto a few soils, which was described by the Freundlich equation with the parameter N >1. The main sorption mechanism of PFOA was hydrophobic interaction between the perfluorinated carbon chain and the organic matter of soil, as evidenced by the correlation between the solid-liquid distribution coefficient and the fraction of soil organic carbon. The sorption of PFOA in soils was highly irreversible. [ABSTRACT FROM AUTHOR]

The distribution and fate of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were investigated in the water and sediment of Bohai Bay, China, during 2011–2013. A total of 360 water samples and 60 sediment samples were collected from 20 locations. The median concentrations of PFOS and PFOA were 4.8 and 12.15 ng/L in the water, and 2.65 and 0.62 ng/g-dry in the sediment, respectively. Significant enrichment were observed for PFOS and PFOA in water of sea surface microlayer. The concentrations of these two compounds showed an apparent gradient from nearshore to offshore stations. The correlation analysis and the distribution tendencies indicated that freshwater inflowing to the bay was the main source of PFOS and PFOA. The salinity of seawater and the total organic carbon (TOC) content of sediment heavily affected the spatial distribution and the partitioning of PFOS and PFOA in the sediment-water system. [ABSTRACT FROM AUTHOR]

Sorption of perfluorinated compounds (PFCs) on carbon nanotubes (CNTs) is critical for understanding their subsequent transport and fate in aqueous environments, but the sorption mechanisms remain largely unknown. In this study, the sorption of six PFCs on CNTs increased with increasing C-F chain length when they had a same functional group, and the CNTs with hydroxyl and carboxyl groups had much lower adsorbed amount than the pristine CNTs, indicating that hydrophobic interaction dominated the sorption of PFCs on the CNTs. Electrostatic repulsion suppressed the sorption of PFCs on the CNTs, resulting in the lower sorption with increasing pH. Hydrogen bonding interaction was negligible. The hydrophobic C-F chains can be closely adsorbed on the CNTs surface in parallel to the axis or along the curvature, making it impossible to form micelles on the CNT surface, leading to the lower sorption than other adsorbents. [Copyright &y& Elsevier]

Abstract: Recent concerns have been raised concerning the widespread distribution of perfluorinated compounds in environmental matrices and biota. The compounds of interest include ammonium perfluorooctanoate (APFO, the ammonium salt of perfluorooctanoic acid, PFOA). APFO is used primarily as a processing aid in the production of fluoropolymers and fluoroelastomers. The environmental presence of perfluorooctanoate (PFO−, the anion of APFO) and its entry into the environment as APFO make quality aquatic toxicity data necessary to assess the aquatic hazard and risk of APFO. We conducted acute and chronic freshwater aquatic toxicity studies with algae, Pseudokirchneriella subcapitata, the water flea, Daphnia magna, and embryo-larval rainbow trout, Oncorhynchus mykiss, using OECD test guidelines and a single, well-characterized sample of APFO. Acute 48–96h LC/EC50 values were greater than 400mg/l APFO and the lowest chronic NOEC was 12.5mg/l for inhibition of the growth rate and biomass of the freshwater alga. Un-ionized ammonia was calculated to be a potential significant contributor to the observed toxicity of APFO. Based on environmental concentrations of PFO− from various aquatic ecosystems, the PNEC value from this study, and unionized ammonia contributions to observed toxicity, APFO demonstrates little or no risk for acute or chronic toxicity to freshwater and marine aquatic organisms at relevant environmental concentrations. [Copyright &y& Elsevier]

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are widespread contaminants in the environment, as well as in wildlife and in humans. The PFOS and PFOA concentrations were determined in historical human serum samples collected in Shenyang, China, in 1987 (n = 15), 1990 (n = 33), 1999 (n = 68) and 2002 (n = 119). The serum donors were students, faculty members and university workers. Since the serum PFOA and PFOS levels did not follow a normal or log-normal distribution, a nonparametric method was applied to analyze the historical trends. For the total male and female subjects, the median level of serum PFOA increased significantly from 0.08 μg/l in 1987 to 4.3 μg/l in 2002 (p < 0.05), while the median level of serum PFOS also increased significantly from 0.03 μg/l in 1987 to 22.4 μg/l in 2002 (p < 0.05). Both the serum PFOA and PFOS levels continued to increase from 1999 to 2002, with remarkable increases observed in females: 6.3-fold increase for PFOA and 13-fold increase for PFOS. In 2002, serum PFOA and PFOS concentrations of female subjects have increased to 4.9 μg/l and 22.4 μg/l in median, respectively, which are comparable to those in U.S.A. and Japan. For male subjects, serum PFOA and PFOS concentrations (1.6 μg/l and 8.3 μg/l in median, respectively) are comparable to those in Italy. The data from this study indicate that females are likely to experience higher exposure to these chemicals. [ABSTRACT FROM AUTHOR]

Abstract: Turtles rank high in the river food chain, and are suitable for predicting the bioconcentrations of chemicals through the food chain. Trachemys scripta elegans () and Chinemys reevesii () were captured in a river in Japan, from September to October 2003 and April to June 2004. Surface water samples were collected simultaneously from the same sites at which the turtles were caught. Serum perfluorooctane sulfonate (PFOS) ranged from 2.4 to 486μg/L, while water PFOS levels ranged from 2.9 to 37ng/L. The geometric mean (GM) (geometric standard deviation, GSD) of the bioconcentration factor (BCF) of PFOS was 10,964 (2.5). In contrast, the perfluorooctanoate (PFOA) level in water ranged from 16.7–87,100ng/L, and serum PFOA ranged from <0.2 to 870μg/L. The GM (GSD) of the BCF of PFOA was 3.2 (7.9). Furthermore, the BCF of PFOA decreased as the PFOA level in the surface water increased. PFOS could be preferentially bioconcentrated in biota, and PFOA, slightly bioconcentrated. [Copyright &y& Elsevier]