Perfluoroalkyl Substances in the Western Tropical Atlantic Ocean

Area of Science:

• Environmental Chemistry
• Oceanography
• Contaminant Hydrology

Background:

• Perfluoroalkyl substances (PFAS) are persistent organic pollutants with widespread environmental presence.
• Understanding PFAS dispersion in marine environments is crucial for assessing ecological and human health risks.

Purpose of the Study:

• To evaluate the dispersion and concentration of PFAS in surface and deep waters of the Western Tropical Atlantic Ocean (TAO).
• To identify dominant PFAS compounds and their distribution patterns across different latitudinal sectors and depths.

Main Methods:

• Analysis of eight quantifiable PFAS (∑8PFAS) in surface and deep-water samples collected across the TAO (15°N to 23°S).
• Assessment of PFAS concentrations (pg/L) and detection frequencies at various depths (down to 5845 m).
• Correlation of PFAS distribution with oceanographic factors like water mass origin, currents, and upwelling.

Main Results:

• Surface water ∑8PFAS concentrations ranged from 11 to 69 pg/L, lower than previously reported.
• Perfluoroalkyl carboxylic acids (PFCAs) were the predominant PFASs; perfluorooctanoic acid (PFOA) was most common (67%).
• PFAS distribution and profiles varied significantly with depth and latitude, with coastal waters showing decreasing concentrations and offshore waters showing higher detection in intermediate depths.

Conclusions:

• PFAS concentrations in the Western TAO are relatively low, with PFCAs being the dominant class.
• Water mass origin, surface currents, and coastal upwelling significantly influence PFAS distribution and profiles in the TAO.
• The study highlights the complex interplay of oceanographic processes in determining contaminant fate in marine ecosystems.