Per- and polyfluoroalkyl substances (PFAS) constitute a diverse group of synthetic organo-fluorinated compounds with a wide range of applications in firefighting foams, cosmetics, textile industry, polymer manufacturing, surfactants etc. These have entered the environment via a wide range of sources and uses, and some can further partially transform into species that are recalcitrant in the environment. Hence, they persist in the environment and are sometimes referred to as ‘forever chemicals’ that are not easily removed via typical pollution treatment facilities such as wastewater treatment plants (WWTP). These chemicals can therefore be detected in water bodies via effluent discharges, impacting water quality and organisms in water bodies.
The potential for long range transport, persistence, bioaccumulation and toxicity of these PFAS have caused these chemicals to be designated as being of emerging concern, and restrictions were imposed on the use of some PFAS. Furthermore, due to their diversity, nature and chemical properties, their analysis in environmental media is challenging. However, techniques that are mostly based on liquid chromatography tandem mass spectrometry (LC-MS/MS) have recently allowed for their detection at the typically low levels (ng/L) found in the environment. The sources, distribution, and risks of PFAS within a catchment are not yet fully understood. Data are particularly limited across Scotland. A Scotland’s Centre of Expertise for Waters report identified a lack of sufficient open access PFAS data to aid in risk assessments in private water supplies. Whilst monitoring programmes, such as the Chemicals Investigation Programme (CIP) 2 and 3 seek to provide data for trend analysis and to build further knowledge and understanding of PFAS in WWTP influents & effluents, gaps still exist on the influence and significance of source pathways (e.g., landfill leachate and industrial waste) which are also managed via WWTP and still need to be investigated. Also, most monitoring programmes have focused on traditional grab sampling, which unfortunately does not provide information on the more environmentally relevant freely dissolved concentrations which delivers information on the bioavailability of these chemicals. Such time-weighted average concentration can be obtained when passive sampling approaches e.g., ChemCatcher or the polar organic chemical integrated sampler (POCIS) are integrated into sampling regimes. Undertaking monitoring within a specific catchment, whereby monitoring is carried out spatially and temporally along with corresponding influent and effluent discharges of WWTP within the catchments will aid in the identification of the sources, levels, and distribution of PFAS chemicals. Monitoring of effluents can aid to further focus PFAS reduction efforts and identify potential risks to receptors.
This project aims to assess the levels and sources of PFAS chemicals in effluent waters within the Ugie and Dee Catchments in the Northeast of Scotland. This will involve:
1. Establishing and validating new analytical techniques (LC-MS/MS) for target PFAS and selected precursors, including novel sampling techniques using passive samplers. Passive sampling provides time-weighted average concentrations which are essential for catchment-scale monitoring and in support of traditional grab sampling.
2. Assessing the risk posed by PFAS chemicals in Scottish waters at catchment-scale with a view to focus PFAS reduction efforts. The influence and significance of other source pathways such as landfill leachate and industrial waste will also be investigated.
3. Proposing a monitoring, mitigation, and management strategy for PFAS in Scottish waters based on findings from the catchment study.