PFAS hotspots in Swedish offshore sediments: Regional patterns and sorption dynamics

Area of Science:

• Environmental Chemistry
• Marine Pollution Studies

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants with widespread environmental presence.
• Offshore sediments can act as sinks and reservoirs for various contaminants, including PFAS.

Purpose of the Study:

• To investigate the distribution and sorption behavior of PFAS in Swedish offshore sediments across five sub-basins.
• To identify factors controlling PFAS accumulation in these marine environments.
• To assess the role of offshore sediments as PFAS reservoirs.

Main Methods:

• Analysis of PFAS concentrations in sediment samples from the Bothnian Bay, Bothnian Sea, Baltic Proper, Southern Baltic, and North Sea.
• Conducting sorption experiments to evaluate PFAS affinity with sediment components.
• Statistical analysis to correlate PFAS levels with sediment properties like organic carbon content.

Main Results:

• Elevated PFAS concentrations were detected, particularly in the northern Swedish offshore basins (Gulf of Bothnia), with total PFAS up to 27 μg kg⁻¹ dry weight.
• PFAS composition varied geographically, with carboxylates dominant in the north and sulfonates in the south.
• Sorption experiments indicated that organic carbon content, not sediment location, was the primary driver of PFAS partitioning.

Conclusions:

• The high PFAS levels in northern basins are primarily source-driven, not controlled by sediment sorption characteristics.
• Offshore sediments serve as significant reservoirs for PFAS, emphasizing their importance in marine pollution.
• Region-specific monitoring and source control strategies are crucial, alongside incorporating sorption dynamics into marine pollution assessments.