Low-Density Plastic Debris Dispersion beneath the Mediterranean Sea Surface

Area of Science:

• Marine pollution
• Oceanography
• Environmental science

Background:

• Plastic debris is a major marine pollutant, with focus often on surface distribution.
• Low-density plastic is increasingly found in the water column and on the seafloor.
• Data on the origin and dispersion of sunken plastic is limited.

Purpose of the Study:

• To investigate the pathways and fate of sinking plastic debris in the Mediterranean Sea.
• To understand the sources and transport mechanisms of plastic pollution reaching the seafloor.
• To assess the shared responsibility for marine plastic pollution among Mediterranean countries.

Main Methods:

• Utilized a Lagrangian plastic-tracking model with realistic parameters.
• Incorporated a maximum estimated sinking speed of 7.8 meters per day.
• Simulated particle trajectories from surface release to seafloor deposition.

Main Results:

• Simulated sinking plastic particles traveled significant lateral distances (119-282 km) from their surface release points.
• Vessels were the source for 60% of plastic particles deposited on the coastal seafloor.
• Biological activities may contribute to plastic sinking throughout the water column.

Conclusions:

• Seafloor plastic pollution in the Mediterranean is a shared responsibility among bordering countries.
• Sunken plastic poses a potential threat to both pelagic and benthic marine organisms.
• Understanding plastic debris pathways is crucial for effective marine pollution management.