First evidence of plastic fallout from the North Pacific Garbage Patch

Area of Science:

• Marine pollution
• Oceanography
• Environmental science

Background:

• Oceanic garbage patches, like the North Pacific Garbage Patch (NPGP), highlight extensive plastic pollution.
• The ultimate fate of plastic debris within these gyres is largely unknown.

Purpose of the Study:

• To investigate the vertical transfer of plastic debris from the NPGP surface into the deep sea.
• To quantify plastic fragment concentrations in the water column below the NPGP.

Main Methods:

• Numerical and mass concentration measurements of plastic fragments (500 µm to 5 cm) in the water column.
• Analysis of polymer composition and size distribution of suspended plastic particles.
• Correlation analysis between surface plastic debris and water column concentrations.

Main Results:

• First evidence of vertical plastic debris transfer from the NPGP into the deep sea.
• Plastic fragment concentrations decline with depth, following a power law.
• Particles in the water column match the size range of those missing from the surface; polymer composition is similar to surface debris (polyethylene, polypropylene).

Conclusions:

• The presence of plastics in the NPGP water column results from the fallout of smaller fragments from surface waters.
• This study elucidates a key pathway for plastic pollution reaching the deep ocean.
• Findings underscore the pervasive nature of plastic pollution across oceanic layers.