A Spatial and Temporal Analysis of PFAS Sources and Loads in the First Industrial River Basin

Locating geographical sources of per- and polyfluoroalkyl substances [PFAS] to rivers, and quantifying the loading attributable to those sources, requires temporal and spatial analysis of PFAS loads across river basins. However, as most studies focus on the measurement of PFAS concentrations, there is a distinct lack of mass loading data for rivers worldwide. As a result, we do not have scientifically robust estimates of how much PFAS enter our rivers from different sources within a river basin or how much PFAS flows from rivers into the oceans.

Here, we present a temporal and spatial analysis of PFAS loads in the River Mersey Basin, England, a heavily industrialised and urbanised river basin. Our primary aim was to locate and quantify sources of PFAS to the river and to elucidate the spatial and temporal dynamics of PFAS transport.

Using a combined field sampling [n = 112] and modelling approach applied at the tributary to river basin-scale, our three-year study provides the first temporally robust estimates of PFAS export for a European river system and identifies the location and magnitude of PFAS river inputs across a major urban river basin.

Analysis of gadolinium anomalies at the river basin-scale reveals approximately 50% of PFAS are associated with effluents from wastewater treatment works [WwTWs]. This is confirmed by a mass balance analysis of river and WwTW PFAS loads. High spatial resolution studies of PFAS loads at the tributary-scale demonstrate large contributions [up to 70% of total loads] from industry and airports. For example, inputs from a major international airport are responsible for 66% of the total perfluorooctane sulfonic acid [PFOS] load in the River Bollin.    

Monitoring and analysis of PFAS river loads, rather than concentrations alone, allows the geographical location and magnitude of PFAS entry to rivers to be established. Temporally robust and catchment-scale PFAS river loading data are essential to help prioritize catchment management and remediation interventions and to reliably estimate the flux of PFAS from river basins to the oceans.