R5 AM Perflourochemical Biodegradation, Fate, and Transport|
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 321-323
637 (KAI-1117-833170) Physicochemical properties of fluorinated compounds: the impact of the F-C bond compared to the H-C bond.
Start time: 8:00 AM
Kaiser, M1, Botelho, M1, Cobranchi, D1, Kao, C-P2, Krusic, P1, Larsen, B1, Marchione, A1, Wooler, G1, Buxton, L3, Buck, R4, 1 DuPont CCAS, Wilmington, DE, USA2 DuPont ER&T, Wilmingtron, DE, USA3 DuPont FLPR, Wilmington, DE, USA4 DuPont DCSE, Wilmington, DE, USA
Measured physicochemical properties are important in the understanding of both environmental transport and exposure. Comparing both measured and literature values, we find significant disagreements for the same compounds. We have measured the solubility and vapor pressure of a variety of fluorinated compounds and also observed their sublimation behavior. We also observed significant differences in the data obtained, depending upon the principles used in the measurements. In this paper we shall report these data along with an explanation for the discrepancies. We shall also suggest some calculations that should be considered for vapor pressure to understand if the measured data are aligned with expectations for homologous series.
638 (SIM-1117-817354) The Adsorption of Perfluorooctanesulfonate onto Sand, Clay, and Iron Oxide Surfaces.
Start time: 8:20 AM
Simcik, Matt1, Smolen, Jean2, Johnson, Ramona1, Anschutz, Amy3, Penn, R3, 1 Department of Chemistry, Saint Joseph's University, Philadelphia, PA, USA2 Department of Chemistry, University of Minnesota, Minneapolis, MN, USA3 Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA
Fluorinated anionic surfactants have drawn considerable attention due to recent work that has shown significant concentrations of these compounds in surface waters. A detailed understanding of the transport and fate of fluorinated surfactants must start with elucidation of their mineral surface chemistry. Five well characterized solids were equilibrated with solutions of perfluorooctanesulfonate (PFOS) in order to characterize adsorption. Adsorbent surface area normalized adsorption isotherms for Goethite, Kaolinite, Ottawa sand standard, high iron sand and low iron sand will be presented. Additionally mass based adsorption isotherms for Lake Michigan sediment will be presented. Good mass balance was obtained during the experiments and equilibrium adsorption was highest on Ottawa sand standard and lowest on Goethite. There appeared to be no effect of pH on adsorption of PFOS to the mineral surfaces.
639 (HIG-1117-751419) Sorption of Perfluorinated Surfactants onto Sediments.
Start time: 8:40 AM
Higgins, C1, Luthy, R1, 1 Department of Civil & Environmental Engineering, Stanford University, Stanford, CA, USA
While perfluorochemicals (PFCs) have been detected in many different environmental media such as air, water, sediment, and biota, data on the partitioning of PFCs between these compartments are scarce. In particular, sorption of PFC surfactants onto sediments has been suspected and measured for a few PFCs such as perfluoroctanesulfonate (PFOS), but it remains unclear whether the organic-carbon partitioning paradigm for hydrophobic organic contaminants is applicable to these chemicals. PFC surfactant sorption may be influenced by other sediment geochemical parameters such as iron and aluminum oxide content, as has been shown for linear alkylbenzene sulfonate (LAS) surfactants. In addition, given the varying chain lengths of PFC surfactants used in the past and currently in use, an understanding of how sorption varies with perfluorocarbon chain length is warranted. To this end, batch sorption isotherm experiments were conducted using -irradiated sediments of varying geochemical compositions and anionic PFC surfactants of varying chain length. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates (PFCAs), perfluoroalkyl sulfonates, and perfluorooctyl sulfonamide acetic acids. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with significant sorption only occurring for PFCs with chain lengths of eight or greater (i.e., PFOS and perfluorononanoate, PFNA). Increasing partition coefficients with increasing chain length were evident for both perfluoroalkyl sulfonates and perfluorocarboxylates, with each CF2 moiety contributing approximately 0.5 log units to the measured partition coefficients. In addition, the perfluorooctyl sulfonamide acetic acids demonstrated substantially stronger sorption than PFOS. This stronger sorption may be at least partially responsible for the differences in relative abundances of PFOS and PFOS precursors observed between sediments and aqueous systems.
640 (LIU-1117-819955) Sorption and Biotransformation of 8:2 Fluorotelomer Alcohol by Surface Soils.
Start time: 9:00 AM
Liu, J1, Nies, L2, Nakatsu, C, Lee, L1, 1 Agronomy Department, Purdue University, West Lafayette, IN, USA2 Civil Engineering Department, Purdue University, West Lafayette, IN, USA
Telomer-based polymers and surfactants serve as excellent surface modification and protective chemicals. However, they are suspected to degrade into perfluorinated acids during disposal and contribute to the global contamination in humans, wide life and environmental compartments. Elucidating the mobility and persistence of fluorotelomer alcohols in soils is an important step towards understanding the fate of these polymers and surfactants in the environment particularly in landfills where products with these coatings such as carpets and paper utensils are disposed. Sorption and biotransformation in soils were investigated for 8:2 fluorotelomer alcohol (CF3-(CF2)7-(CH2)2-OH), which is the most abundant species among fluorotelomer alcohols of different carbon chain lengths. Sorption from aqueous solutions by five soils representing a wide range of properties was determined directly and extrapolated from data measured in acetone/water solutions using a log-linear cosolvency model, which minimizes experimental artifacts from volatilization, degradation, and dissolved organic carbon (DOC). Extrapolated aqueous sorption coefficients from the cosolvency method were in good agreement but consistently higher than those measured directly, which was attributed to fluorotelomer alcohol association with the DOC in aqueous solutions. 8:2 fluorotelomer alcohol sorption was exothermic and appeared to be primarily driven by hydrophobic partitioning with a log Koc value (OC-normalized soil-water distribution coefficient, L/kg) of 4.13±0.16, which is comparable to a 3-ring polyaromatic hydrocarbon. Aerobic biotransformation was investigated in the presence of different organic co-substrates (methanol, ethanol, octanol, acetone, ethyl acetate, and 1,4-dioxane). The high volatility of the 8:2 fluorotelomer alcohol requires that it be added to soil microcosms via a cosolvent. In a preliminary 7-day, the 8:2 fluorotelomer alcohol was aerobically transformed into 8:2 saturated and unsaturated acids with all co-substrates. Longer incubation studies are being conducted to assess if pathways for further transformation, reaction rates, and microbial consortium are affected by co-substrates.
(58108) COFFEE BREAK.
Start time: 9:20 AM
641 (WAN-1117-037677) Microbial Biotransformation Pathways of 8-2 Fluorotelomer Alcohol (FTOH).
Start time: 10:00 AM
Wang, N1, Szostek, B2, Buck, R3, Folsom, P1, Powley, C2, Berti, W1, 1 DuPont Central Research and Development, Newark, DE, USA2 DuPont Haskell Laboratory, Newark, DE, USA3 DuPont Chemical Solutions Enterprise, Wilmington, DE, USA
The fluorotelomer raw material intermediate 8-2 Telomer B Alcohol [CF3(CF2)7CH2CH2OH; 8-2 FTOH ] is a principal raw material used to manufacture fluorotelomer-based products. If a fluorotelomer-based product were biodegradable in the environment, the 8-2 FTOH would be an expected initial degradation product, which may be subsequently transformed in the environment. We have investigated the biotransformation of 14C-labeled 8-2 FTOH [CF3(CF2)614CF2CH2CH2OH] by soil, activated sludge, sediment, and mixed bacterial culture over a period up to 7-month to determine the pathways of biotransformation in these matrices. We have found that the 8-2 FTOH can be readily transformed by microorganisms. The experimental methods, observed stable and transient transformation products, and proposed biotransformation pathways will be presented. In all studies, biodegradation to form products with less than eight carbons has been observed. The implications of these results in relation to the potential contribution of FTOH raw materials and fluorotelomer-based polymeric products to the presence of perfluorinated carboxylic acids in the environment will also be discussed.
642 (BER-1117-855591) Biodegradation studies of fluorotelomer-based polymers in activated sludge, soil, and sediment.
Start time: 10:20 AM
Berti, William1, Szostek, Bodan2, Schaefer, Edward3, Van Hoven, Raymond3, Wang, Ning1, Gannon, John1, Buck, Robert4, 1 DuPont Central Research and Development, Newark, DE, USA2 DuPont Haskell Laboratory for Health and Environmental Sciences, Newark, DE, USA3 Wildlife International, Ltd., Easton, MD, USA4 DuPont Chemical Solutions Enterprise, Wilmington, DE, USA
Biodegradation of fluorotelomer-based polymers in the environment is of interest to determine whether they may be a potential source of perfluorinated carboxylic acids (PFCAs). Studies to determine whether the fluorotelomer moieties covalently bonded in these polymers can be liberated and transformed to PFCAs are underway. The biodegradation studies are being conducted in aerobic sludge and under aerobic and anaerobic conditions in soils and sediments. Treatments for the soil studies include an untreated control soil, live (non-sterilize) soil containing the test substance (i.e., commercially-sold polymer product emulsion) added at 200 mg polymer kg-1 soil (soil dry wt.), sterilized soil containing the test substance, and sterilized soil containing 8-2 Telomer B Alcohol (8-2 TBA), two telomer acids, and 8, 9, 10, and 11 carbon-containing PFCAs to assess recoveries over the year-long experiment. The test vessels are incubated statically at 20°C. Anaerobic conditions are imposed by flushing the test vessels with anaerobic mixed gas and then sealing them. Treatments and methods for the sediment studies are similar to those of the soil studies. Sediment and water are added to each test vessel so the resulting water:sediment volume ratio is between 3:1 and 4:1 and the minimum sediment layer is approximately 2 cm. In addition to headspace and sediment extract samples, separate aqueous samples are collected and analyzed for the sediment studies. Analyses of the test systems from the activated sludge and soil studies indicate that ppb levels of 8-2 TBA, two telomer acids, and 8 to 11 carbon-containing PFCAs extracted from soils are accounted for by transformation of residual fluorotelomer raw materials present in the polymer products.
643 (WAS-1118-340637) Design of Biodegradation Experiments for Fluorotelomer-Based Polymers.
Start time: 10:40 AM
Washington, John1, Ellington, J.1, Jenkins, Thomas1, Evans, John1, Henderson, W1, 1 USEPA, National Exposure Research Laboratory, Ecosystems Research Division, 960 College Station Rd., Athens, Georgia, USA
Fluorotelomer-based polymers (FBPs) are used in a wide variety of consumer products and are widely distributed throughout society. Accordingly, there is great interest in whether and how fast these materials might degrade in various environmental settings. Known and expected qualities of FBPs and fluorinated monomers, as well as extraction and analytical considerations, contribute challenges in logical design of FBP-biodegradation studies to avoid artifacts. Microbial enzyme induction for degradation of FBPs, should it occur, could be long relative to typical periods for biodegradation experiments; consequently, it might be advisable to collect and test acclimated as well as pristine media. A useful quality of FBPs is the chemical stability of the polymers and, therefore, half-lives are anticipated to be long relative to typical laboratory experiments. Failure to account for this stability in experimental design can affect results by: i) yielding unsatisfactory resolution of reaction rate to quantitate degradation constants; and ii) ingrowth of potential degradation products could be insufficient to determine whether the products are from leaching of residual monomers in the FBP or microbially mediated breakdown of the FBP structure. Consequently, sufficient microcosms, resources and time should be allotted to allow extended incubations. The compatibility of potential perfluorinated degradation products with glass, Teflon and other common experimental materials is uncertain with respect to irreversible sorption, diffusivity and extraneous sources of perfluorinated compounds; consequently, experimental materials must be tested for compatibility with potential degradation products. Maintenance of the air-tight integrity of reaction vessels is critical so that volatile potential degradation products will not diffuse from the containers over long experiments; this is especially relevant considering possible constraints on acceptable materials for sealing containers. Consequently, integrity of microcosm containers must be confirmed experimentally. We report: 1) how these and similar factors have affected our experimental design; and 2) on our early experimental efforts.
644 (MAB-1117-777215) Fate of FTOHs in the Environment.
Start time: 11:00 AM
Mabury, Scott1, 1 University of Toronto, Toronto, ON, Canada
The chemical architecture of the alkyl fluorine bond imparts unique and useful properties such that it is now widely utilized in both consumer and industrial applications. Some of these properties result in fugitive emissions of fluorinated alkyl compounds that are subsequently widely dispersed in the environment, bioaccumulative, and yield highly persistent and potentially toxic degradation products. Of particular interest are the fluorotelomer alcohols (FTOHs) that are widely incorporated into polymers for the paper, carpet, and textile markets. Residual FTOHs are present in significant quantities in fluorinated polymers and data suggests they may be the dominant source of these perfluorinated alkyl acid (PFCAs) precursors in the atmosphere. FTOHs are widely observed across North America in the 10 to 100 pg/m3 range. They react primarily with OH leading to a lifetime on the order of 20 days, sufficient for significant long-range transport. The sole degradation product is the FTOH aldehyde, also long-lived, which proceeds through successive OH initiated reactions to ultimately yield the FTOH acids, perfluorinated aldehydes, PFCAs (1 to 10%), and carbonyl fluoride as the dominant product. PFCAs appear in the majority of biological samples tested and are particularly high in remote Arctic regions in species at the top of the food chain. The PFCA isomer signature suggests a linear alkyl source thereby ruling out an electrochemical process. Metabolism studies, in both microbes and rats, show analogous transformation pathways leading to PFCAs, as well as highly reactive intermediates. Substantial evidence now supports an overall theory that FTOHs are the primary source of PFCAs in the remote environment and may be important in human exposures.
645 (BUC-1117-824039) What is the Environmental Fate of 8-2 Fluorotelomer Alcohol? Facts & Myths.
Start time: 11:20 AM
BUCK, R1, KORZENIOWSKI, S1, WATERLAND, R2, WANG, N2, BERTI, W2, GANNON, J2, SZOSTEK, B3, POWLEY, C3, KAISER, M2, 1 DUPONT CHEMICAL SOLUTIONS ENTERPRISE, WILMINGTON, DE, USA2 DUPONT CENTRAL RESEARCH & DEVELOPMENT, WILMINGTON, DE, USA3 DUPONT HASKELL LABORATORY, NEWARK, DE, USA
Fluorotelomer alcohols [F(CF2CF2)nCH2CH2OH; FTOHs] are a raw material used in the manufacture of fluorotelomer-based surfactant and polymeric products. FTOHs are present as residual raw materials in products at low levels, tenths of a percent or less. In addition, FTOHs are expected to be a product from degradation of products should that occur. They have been the focus of much scientific investigation to understand their physical-chemical properties as well as their environmental fate. The most widely studied FTOH is 8-2 FTOH (n=4). While it has been portrayed that 8-2 FTOH degrades exclusively to perfluorooctanoic acid (PFOA) in the environment, the scientific facts suggest otherwise. This paper will review existing data as well as summarize the latest studies to investigate the abiotic and biotic degradation of 8-2 FTOH in the atmosphere, sludge, soil and mammals. The results from recently completed studies in these matrices show that PFOA is generally only a minor transformation product from degradation of 8-2 FTOH. Integral to fate investigations are physical-chemical and partitioning properties. The implications of recent measurements will be interwoven into the presentation.