PFAS River Export Analysis Highlights the Urgent Need for Catchment-Scale Mass Loading Data

Source apportionment
of per- and polyfluoroalkyl substances (PFAS)
requires an understanding of the mass loading of these compounds in
river basins. However, there is a lack of temporally variable and
catchment-scale mass loading data, meaning identification and prioritization
of sources of PFAS to rivers for management interventions can be difficult.
Here, we analyze PFAS concentrations and loads in the River Mersey
to provide the first temporally robust estimates of PFAS export for
a European river system and the first estimates of the contribution
of wastewater treatment works (WwTWs) to total river PFAS export.
We estimate an annual PFAS export of 68.1 kg for the River Mersey
and report that the yield of perfluorooctanesulfonic acid (PFOS) and
perfluorooctanoic acid (PFOA) in the catchment is among the highest
recorded globally. Analysis of river and WwTW loads indicates approximately
one-third of PFOA emitted from WwTWs is potentially stored in the
catchment and approximately half of PFOS transported by the River
Mersey may not originate from WwTWs. As governments move toward regulation
of PFAS in WwTW effluents, our findings highlight the complexity of
PFAS source apportionment and the need for catchment-scale mass loading
data. This study indicates that strategies for reducing PFAS loading
that focus solely on WwTW effluents may not achieve river water quality
targets.