Modeling Global-Scale Fate and Transport of Perfluorooctanoate Emitted from Direct Sources

Abstract

The long-term (1950-2050) global fate of perfluorooctanoate (PFO) is investigated using the global distribution model, GloboPOP. The model is used to test the hypotheses that direct PFO emissions can account for levels observed in the global oceans and that ocean water transport to the Arctic is an important global distribution pathway. The model emission scenarios are derived from historical and projected PFO emissions solely from direct sources. Modeled ocean water concentrations compare favorably to observed PFO concentrations in the world's oceans and thus ocean inventories can be accounted for by direct sources. The model results support the hypothesis that long-range ocean transport of PFO to the Arctic is important and estimate a net PFO influx of approximately 8-23 tons per year flowing into the model's Northern Polar zone in 2005, an amount at least 1 order of magnitude greater than estimated PFO flux to the Arctic from potential indirect sources such as atmospheric transport and degradation of fluorotelomer alcohols. Modeled doubling times of ocean water concentrations in the Arctic between 1975 and 2005 of approximately 7.5-10 years are in good agreement with doubling times of PFO in Arctic biota estimated from monitoring data. The model is further applied to predict future trends in PFO contamination levels using forecasted (2005-2050) direct emissions, including substantial reductions committed to by industry. Modeled ocean water concentrations in zones near to sources decline markedly after 2005, whereas modeled concentrations in the Arctic are predicted to continue to increase until approximately 2030 and show no significant decrease for the remaining 20 years of the model simulation. Since water is the primary exposure medium for Arctic biota, these model results suggest that concentrations in Arctic biota may continue to rise long after direct emissions have been substantially reduced or eliminated.

Spatial distribution of per- and polyfluoroalkyl compounds in coastal waters from the East to South China Sea

“…Overall, the spatial distribution data obtained in this study is useful for global transport models (Armitage et al, 2006), in which industrial areas are considered as source of PFCs, and ocean water is important as a sink and for transport of these compounds. The ubiquitous presence of PFCs along the coast is an indicator of their widespread distribution and gives evidence on the risk that may pose to the overall area.…”

“…Interestingly, the concentration of PFOA was relatively high in seawaters of Iceland and Faroe Islands in the Arctic environment (Kallenborn et al, 2004). This can be explained by neutral, volatile precursor compounds, which can undergo long-range atmospheric transport and be degraded in remote regions Martin et al, 2006;Schenker et al, 2008) or by the direct transport of ionic PFCs by oceanic currents or by means of sea-spray (Armitage et al, 2006;McMurdo et al, 2008).…”

Distribution and long-range transport of polyfluoroalkyl substances in the Arctic, Atlantic Ocean and Antarctic coast

“…Significant relationship had been reported between PFASs concentration and mortal disease in marine organisms, and world wide detection of PFASs in serum has been of utmost concern Bonefeld-Jorgensen et al, 2011;Shankar et al, 2011). Armitage et al (2006) estimated that the PFOA flux to Arctic region was 8e23 t/a from direct emissions, and Prevedouros et al (2006) calculated the amount of perfluorooctanoic acid (PFOA) transported to the Arctic Ocean by water as 2e12 t/a. Hydrospheric transport was stressed due to the larger amount of PFASs in marine water than in air, although higher concentrations were measured in Arctic snow, which resulted from atmospheric deposition (Theobald et al, 2007).…”

Neutral poly- and perfluoroalkyl substances in air and seawater of the North Sea

“…Degradation of these precursors may account for the presence of PFOA and PFOS in remote regions (Andersen et al 2005;D'Eon et al 2006;Ellis et al 2004;Martin et al 2006;Zhao et al 2012). Apart from atmospheric reaction, degradation of FTOHs and FTSEs/FOSAs in the aquatic phase can be an additional source for PFCAs and PFSAs, especially in the remote oceans (Armitage et al 2006(Armitage et al , 2009Cousins et al 2011). Therefore, it would be very interesting to study neutral PFASs in the aquatic environment.…”