Potential role of sea spray generation in the atmospheric transport of perfluorocarboxylic acids
Centre for Environmental Modelling and Chemistry, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada. Environmental Toxicology and Chemistry
(Impact Factor: 3.23).
08/2010; 29(8):1703-8. DOI: 10.1002/etc.228
The observed environmental concentrations of perfluorooctanoic acid (PFOA) and its conjugate base (PFO) in remote regions such as the Arctic have been primarily ascribed to the atmospheric transport and degradation of fluorotelomer alcohols (FTOHs) and to direct PFO transport in ocean currents. These mechanisms are each capable of only partially explaining observations. Transport within marine aerosols has been proposed and may explain transport over short distances but will contribute little over longer distances. However, PFO(A) has been shown to have a very short half-life in aqueous aerosols and thus sea spray was proposed as a mechanism for the generation of PFOA in the gas phase from PFO in a water body. Using the observed PFO concentrations in oceans of the Northern Hemisphere and estimated spray generation rates, this mechanism is shown to have the potential for contributing large amounts of PFOA to the atmosphere and may therefore contribute significantly to the concentrations observed in remote locations. Specifically, the rate of PFOA release into the gas phase from oceans in the Northern Hemisphere is calculated to be potentially comparable to global stack emissions to the atmosphere. The subsequent potential for atmospheric degradation of PFOA and its global warming potential are considered. Observed isomeric ratios and predicted atmospheric concentrations due to FTOH degradation are used to elucidate the likely relative importance of transport pathways. It is concluded that gas phase PFOA released from oceans may help to explain observed concentrations in remote regions. The model calculations performed in the present study strongly suggest that oceanic aerosol and gas phase field monitoring is of vital importance to obtain a complete understanding of the global dissemination of PFCAs.
Available from: Rainer Lohmann
- "In the oceans, perfluorooctanoic acid (PFOA) is the most frequently detected PFCA, and often detected at greatest concentrations (Yamashita et al., 2005, 2008). Per-and polyfluoroalkyl substances compounds are transported away from their production and use locations by a combination of transport with ocean currents (Armitage et al., 2006), atmospheric transport and oxidation of fluorotelomer alcohols (Ellis et al., 2003), and transport with sea-salt aerosols (McMurdo et al., 2008; Webster and Ellis, 2008). Perflourinated compounds have been detected in biota, including humans world-wide (Giesy and Kannan, 2002; Houde et al., 2006). "
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ABSTRACT: Here we estimate the importance of vertical eddy diffusion in removing perfluorooctanoic acid (PFOA) from the surface Ocean and assess its importance as a global sink. Measured water column profiles of PFOA were reproduced by assuming that vertical eddy diffusion in a 3-layer ocean model is the sole cause for the transport of PFOA to depth. The global oceanic sink due to eddy diffusion for PFOA is high, with accumulated removal fluxes over the last 40 years of 660 t, with the Atlantic Ocean accounting for 70% of the global oceanic sink. The global oceans have removed 13% of all PFOA produced to a depth greater than 100 m via vertical eddy diffusion; an additional 4% has been removed via deep water formation. The top 100 m of the surface oceans store another 21% of all PFOA produced (∼1100 t).
Available from: Andrew J. Peters
- "Only recently was a model developed that included a preliminary representation of aqueous aerosols as a separate environmental compartment not at equilibrium with the atmosphere (Webster et al., 2010). It is noteworthy that for models of chemical fate in indoor environments, the two-resistance film theory will also underestimate the effect of such domestic water uses as showering (Webster et al., 2010). There is a clear need for field measurements to address the question of the degree of enrichment of sea spray aqueous aerosol with surfactants and hence their importance in this class of chemicals with regard to atmospheric transport. "
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ABSTRACT: Nonylphenol ethoxylates (NPEOs) are environmentally ubiquitous non-ionizing surfactants that show a preference for the air–water interface. They are therefore potentially subject to enhanced transport by aqueous aerosols. The extent to which aqueous aerosols affect the overall environmental fate and behavior of NPEOs is investigated with a combination of laboratory and field experiments and mathematical modeling. Aqueous aerosol droplets were generated in a laboratory-based experimental system. Aqueous aerosols were measured to have concentrations of NPEOs at least four times greater than in the bulk source water.The concentration of nonylphenol and nonylphenol monoethoxylate in aqueous aerosols off the coast of Bermuda were 4.3–19.2 times higher than in coastal water and open water collected from the Bermuda Atlantic Time Series sampling site. Coastal water showed higher concentrations than open water samples ranging from 36 to 51 ng L−1 and 14 to 21 ng L−1 respectively. Depth profiling showed a loss of detection below 300 m. Aqueous aerosol enrichment was demonstrated and relative atmospheric concentrations ranged from 0.28 to 1.8 ng m−3. A generic marine model was developed using independent North Sea data to estimate the relative potential for NPEO transfer within spray droplets to the atmosphere and subsequently into the gas phase by volatilization. The results were compared to the estimated direct volatilization from the surface of a natural water body. The upward mass flux of NPEOs by direct volatilization was comparable in magnitude to the fluxes due to spray generation, depending on the wind speed and droplet sizes. The experimental results and the model calculations were illustratively applied to reported NPEO concentrations in the North Sea. Aerosol generation provides a feasible mechanism for atmospheric transport of NPEOs and their degradation products, nonylphenols (NPs).
Available from: Lutz Ahrens
- "  Second, neutral, volatile precursors, such as fluorotelomer alcohols (FTOHs), fluorinated sulfonamides, and sulfonamidoethanols (FOSAs and FOSEs), could undergo long-range atmospheric transport and be degraded in remote regions to perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs),  or third, direct atmospheric gas phase or aerosol-mediated transport of PFCAs and PFSAs is possi- ble.    The last two hypotheses are supported by the determination of precursors in urban and remote atmosphere and PFCAs/PFSAs in aerosols.   In addition, PFCAs and PFSAs were detected in arctic snow samples, which indicates a CSIRO PUBLISHING L. Ahrens et al., Environ. "
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ABSTRACT: Perfluoroalkyl compounds (PFCs) and total mercury (THg) were investigated in fish liver collected from four high-mountain lakes in the French alps in which the water was fed only by atmospheric deposition. Concentrations of various PFCs, including C9-C15 perfluoroalkyl carboxylates (PFCAs) and perfluorooctane sulfonate (PFOS) were quantified. The PFOS concentration was similar in all high-mountain lakes with mean concentrations ranging from 3.61- 4.24 ng g1 wet weight (ww) indicating homogeneous atmospheric deposition. Conversely, the spatial distribution of PFCAs and THg was strongly influenced from a different emission source, which is probably the city of Grenoble, which resulted in significantly higher concentration levels of PPFCAs in three lakes (Po0.001) and of THg in two lakes (Po0.05) located easterly from Grenoble. Furthermore, the positive correlation between PFCAs and THg suggest similar transport and bioaccumulation pathways. The contribution of the longer chain PFCAs decreased with increasing distance from the local source area of Grenoble, which could be attributed to their less pronounced transport potential. Results from this study demonstrate that the contamination of PFCs and THg in the fish of the high-mountain lakes originated from atmospheric deposition and subsequent bioaccumulation.
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