Characterizing PFASs in aquatic ecosystems with 3D hydrodynamic and water quality models

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Environmental Modeling

Background:

• Understanding the complex pathways of per- and polyfluoroalkyl substances (PFASs) into aquatic environments is crucial.
• Spatiotemporal dynamics and transport mechanisms of PFASs across different environmental matrices are not well understood.

Purpose of the Study:

• To investigate the fate and transport mechanisms of PFASs in an estuarine reservoir.
• To quantify the distribution of total PFASs, perfluorooctanoate (PFOA), and perfluorooctane sulfonate (PFOS) across water, particulate matter, and sediments.
• To assess the potential ecological risks associated with PFASs in the reservoir.

Main Methods:

• Integration of monitoring data with a detailed 3D model incorporating hydrological, hydrodynamic, and water quality processes.
• Validation of model results against four years of field measurements.
• Quantification of PFAS distribution in dissolved, particulate, and sediment phases.

Main Results:

• The majority of PFASs (>95%) were found in the dissolved phase, with smaller fractions associated with detritus (1.0-3.5%) and phytoplankton (1-2%).
• Risk quotients for PFOS (<0.32) and PFOA (<0.00016) indicate acceptable risk levels in the reservoir.
• The reservoir demonstrated significant buffering capacity against a tenfold increase in external PFAS loading, especially for PFOA.

Conclusions:

• The integrated modeling approach effectively characterizes PFAS occurrence, sources, sinks, and trends in aquatic ecosystems.
• The study enhances understanding of contaminant transport and provides a framework for investigating mitigation strategies for emerging contaminants.
• Estuarine reservoirs can possess substantial capacity to mitigate risks from PFAS contamination.