title: Comparing measured and modelled PFOS concentrations in a UK freshwater catchment and estimating emission rates.
abstract: The lifecycle, sources and fate of perfluorooctane sulfonate (PFOS) continue to generate scientific and political interest, particularly since PFOS was listed by the Stockholm Convention and largely restricted in Europe. It continues to be detected in aquatic environments, with only limited studies into the on-going sources. This paper explores PFOS emissions discharged by the general population into a small catchment comprising two rivers in the UK. A sampling campaign was undertaken to improve our understanding of population-derived PFOS sources from sewage treatment plants (STPs) and in rivers. A corresponding modelling exercise allowed an emission estimate of 13μg/day/per capita to be derived for the Aire and Calder rivers. PFOS emission was linked to STP discharges bylinear regression of measured and modelled concntrations (R(2)=0.49-0.85). The model was able to accurately estimate the spatial trends of PFOS in the rivers, while predicted concentrations were within a factor of three based on per capita emission values taken from the literature. Measured PFOS concentrations in rivers suggested that emissions from STPs are partially dependent on treatment type, where plants with secondary or tertiary treatment such as activated sludge processes emit less PFOS, possibly due to increased partitioning and retention. With refinements based on the type of treatment at each STP, predictions were further improved. The total PFOS mass discharged annually via rivers from the UK has been estimated to be between 215 and 310kg, based on the per capita emission range derived in this study.
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Earnshaw
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Paul
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy.
authors.forename: Robert
authors.initials: R
authors.lastname: Loos
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Tavazzi
authors.affiliation: European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Paracchini
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Scheringer
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: Konrad
authors.initials: K
authors.lastname: Hungerbühler
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Jones
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK; Centre for Ecology and Hydrology, LA1 4AP, UK. Electronic address: a.sweetman@lancaster.ac.uk.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sweetman
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry*; D004784:Environmental Monitoring; D005466:Fluorocarbons / Q000737:chemistry*; D007700:Kinetics; D008962:Models, Theoretical; D045483:Rivers / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry; D006113:United Kingdom; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017738:Alkanesulfonic Acids; D005466:Fluorocarbons; D012722:Sewage; D014874:Water Pollutants, Chemical; C076994:perfluorooctane sulfonic acid
keywords: Emissions; Modelling; Monitoring; Perfluorooctane sulfonate; River Aire; Stockholm Convention