Perfluorinated acids as novel chemical tracers of global circulation of ocean waters

• Published in: Chemosphere (Oxford) Vol. 70; no. 7; pp. 1247 - 1255
• Main Authors: Yamashita, Nobuyoshi, Taniyasu, Sachi, Petrick, Gert, Wei, Si, Gamo, Toshitaka, Lam, Paul K.S., Kannan, Kurunthachalam
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2008; Elsevier
• Subjects: Alkanesulfonic Acids - analysis; Caprylates - analysis; Chemical tracer; Deep seawater; Earth, ocean, space; Environmental Monitoring; Exact sciences and technology; External geophysics; Fluorocarbons - analysis; Global circulation; Marine; Other topics; Perfluorinated chemicals; PFOA; PFOS; Physics of the oceans; Seawater - analysis; Water Pollutants, Chemical - analysis; AN, North Atlantic; IS, South Pacific; ANW, Atlantic, Labrador Current; ANE, Atlantic, Denmark Strait, Denmark Strait Overflow Water; ANW, Labrador Sea; ISW, Indian Ocean; AN, North Atlantic, North Atlantic Current; Global circulation; Chemical tracer; PFOA; Perfluorinated chemicals; Deep seawater; PFOS; ocean currents; world ocean; tracers; Sulfonate; Persistent organic pollutant; Spatial distribution; Depth profile; Organic fluorine compounds; Carboxylate; Water pollution; organic compounds; ocean circulation; Chemical contamination; Concentration distribution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.07.079

Perfluorinated acids (PFAs) such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are global environmental contaminants. The physicochemical properties of PFAs are unique in that they have high water solubilities despite the low reactivity of carbon-fluorine bond, which also imparts high stability in the environment. Because of the high water solubilities, the open-ocean water column is suggested to be the final sink for PFOS and PFOA. However, little is known on the distribution of PFAs in the oceans around the world. Here we describe the horizontal (spatial) and vertical distribution of PFAs in ocean waters worldwide. PFOS and PFOA concentrations in the North Atlantic Ocean ranged from 8.6 to 36 pg l −1 and from 52 to 338 pg l −1, respectively, whereas the corresponding concentrations in the Mid Atlantic Ocean were 13–73 pg l −1 and 67–439 pg l −1. These were completely different from the surface waters of the South Pacific Ocean and the Indian Ocean (overall range of <5–11 pg l −1 for PFOS and PFOA). Vertical profiles of PFAs in the marine water column were associated with the global ocean circulation theory. Vertical profiles of PFAs in water columns from the Labrador Sea reflected the influx of the North Atlantic Current in surface waters, the Labrador Current in subsurface waters, and the Denmark Strait Overflow Water in deep layers below 2000 m. Striking differences in the vertical and spatial distribution of PFAs, depending on the oceans, suggest that these persistent acids can serve as useful chemical tracers to allow us to study oceanic transportation by major water currents. The results provide evidence that PFA concentrations and profiles in the oceans adhere to a pattern consistent with the global “Broecker’s Conveyor Belt” theory of open ocean water circulation.