The sorption of anionic perfluorochemical (PFC) surfactants of varying chain lengths to sediments was investigated using natural sediments of varying iron oxide and organic carbon content. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates, perfluorosulfonates, and perfluorooctyl sulfonamide acetic acids. PFC surfactant sorption was influenced by both sediment-specific and solution-specific parameters. Sediment organic carbon, rather than sediment iron oxide content, was the dominant sediment-parameter affecting sorption, indicating the importance of hydrophobic interactions. However, sorption also increased with increasing solution [Ca2+] and decreasing pH, suggesting that electrostatic interactions play a role. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with each CF2 moiety contributing 0.50-0.60 log units to the measured distribution coefficients. The sulfonate moiety contributed an additional 0.23 log units to the measured distribution coefficient, when compared to carboxylate analogs. In addition, the perfluorooctyl sulfonamide acetic acids demonstrated substantially stronger sorption than perfluorooctane sulfonate (PFOS). These data should prove useful for modeling the environmental fate of this class of contaminants.

Currently there are few ideal methods for the characterization of nanoparticles in complex, environmental samples, leading to significant gaps in toxicity and exposure assessments of nanomaterials. Single particle-inductively coupled plasma-mass spectrometry (spICP-MS) is an emerging technique that can both size and count metal-containing nanoparticles. A major benefit of the spICP-MS method is its ability to characterize nanoparticles at concentrations relevant to the environment. This paper presents a practical guide on how to count and size nanoparticles using spICP-MS. Different methods are investigated for measuring transport efficiency (i.e. nebulization efficiency), an important term in the spICP-MS calculations. In addition, an alternative protocol is provided for determining particle size that broadens the applicability of the technique to all types of inorganic nanoparticles. Initial comparison, using well-characterized, monodisperse silver nanoparticles, showed the importance of having an accurate transport efficiency value when determining particle number concentration and, if using the newly presented protocol, particle size. Ultimately, the goal of this paper is to provide improvements to nanometrology by further developing this technique for the characterization of metal-containing nanoparticles.

Perfluorochemicals (PFCs) are the subject of increasingly intense environmental research. Despite their detection both in biota and in aqueous systems, little attention has been paid to the possible presence of this class of compounds in solid environmental matrixes. The limited available data indicate that some PFCs such as perfluorooctane sulfonate (PFOS) may strongly sorb to solids, and sewage sludge is widely suspected as a major sink of PFCs entering municipal waste streams. A quantitative analytical method was developed that consists of liquid solvent extraction of the analytes from sediments and sludge, cleanup via solid-phase extraction, and injection of the extracts with internal standards into a high-performance liquid chromatography (HPLC) system coupled to a tandem mass spectrometer (LC/MS/MS). The limits of detections of the method were analyte and matrix dependent, but ranged from 0.7 to 2.2 ng/g and 0.041 to 0.246 ng/g (dry weight) for sludge and sediment, respectively. A demonstration of the method was performed by conducting a limited survey of domestic sludge and sediments. The concentration of PFCs in domestic sludge ranged from 5 to 152 ng/g for total perfluorocarboxylates and 55 to 3370 ng/g for total perfluoroalkyl sulfonyl-based chemicals. Data from a survey of San Francisco Bay Area sediments suggest widespread occurrence of PFCs in sediments at the low ng/g to sub-ng/g level. Furthermore, substances that may be transformed to PFOS, such as 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA) and 2-(N-methylperfluorooctanesulfonamido) acetic acid (N-MeFOSAA), are present in both sediments and sludge at levels often exceeding PFOS.

Fluorochemicals have widespread applications and are released into municipal wastewater treatment plants via domestic wastewater. A field study was conducted at a full-scale municipal wastewater treatment plant to determine the mass flows of selected fluorochemicals. Flow-proportional, 24-h samples of raw influent, primary effluent, trickling filter effluent, secondary effluent, and final effluent and grab samples of primary, thickened, activated, and anaerobically-digested sludge were collected over ten days and analyzed by liquid chromatography electrospray-ionization tandem mass spectrometry. Significant decreases in the mass flows of perfluorohexane sulfonate and perfluorodecanoate occurred during trickling filtration and primary clarification, while activated sludge treatment decreased the mass flow of perfluorohexanoate. Mass flows of the 6:2 fluorotelomer sulfonate and perfluorooctanoate were unchanged as a result of wastewater treatment, which indicates that conventional wastewater treatment is not effective for removal of these compounds. A net increase in the mass flows for perfluorooctane and perfluorodecane sulfonates occurred from trickling filtration and activated sludge treatment. Mass flows for perfluoroalkylsulfonamides and perfluorononanoate also increased during activated sludge treatment and are attributed to degradation of precursor molecules.