Nanoplastic concentrations across the North Atlantic.

Area of Science:

• Environmental Science
• Oceanography
• Chemical Oceanography

Background:

• Marine plastic pollution is a global issue, with research focusing on macro and microplastics.
• Ocean nanoplastics (<1 μm) are largely unquantified, creating a gap in understanding plastic mass budgets.
• Existing studies have not fully addressed the scale and impact of nanoplastics in marine environments.

Purpose of the Study:

• To quantify nanoplastic concentrations across the North Atlantic water column.
• To assess the contribution of nanoplastics to the overall marine plastic mass budget.
• To investigate the distribution patterns of nanoplastics from subtropical gyres to shelf areas.

Main Methods:

• Ocean-basin scale transect sampling across the North Atlantic.
• Measurement of nanoplastic concentrations (polyethylene terephthalate, polystyrene, polyvinyl chloride) in the water column.
• Comparison of nanoplastic concentrations between mixed layer, intermediate, and bottom waters.

Main Results:

• Nanoplastic concentrations ranged from 1.5-32.0 mg m⁻³ throughout the North Atlantic water column.
• Mixed layer nanoplastics were 1.4 times higher than intermediate depths, with peaks near Europe.
• Subtropical gyre intermediate waters showed 1.8 times higher nanoplastic concentrations than the open North Atlantic.
• Bottom waters had the lowest concentrations (~5.5 mg m⁻³), primarily polyethylene terephthalate.
• Estimated mixed layer nanoplastic mass in the temperate to subtropical North Atlantic reached 27 million tonnes.

Conclusions:

• Nanoplastics constitute a substantial, potentially dominant, fraction of marine plastic pollution.
• The estimated mass of nanoplastics rivals or exceeds previous estimates for macro/microplastics in oceans.
• Further research is crucial to understand the full impact and fate of nanoplastics in marine ecosystems.