Plastic in the Thames: a river runs through it.

Area of Science:

• Environmental Science
• Marine Biology
• Pollution Studies

Background:

• Marine plastic pollution is a recognized global issue.
• The contribution of freshwater catchments to this pollution is understudied.
• Submerged plastic debris poses an underestimated threat to marine ecosystems.

Purpose of the Study:

• To quantify submerged plastic pollution originating from freshwater catchments.
• To identify the types and sources of plastic debris in the Thames estuary.
• To assess the significance of sub-surface plastic flows into marine environments.

Main Methods:

• Deployment of eel fyke nets at seven localities in the upper Thames estuary over three months (September-December 2012).
• Interception and quantification of submerged plastic items.
• Analysis of plastic item types, with specific attention to sanitary product components.
• Identification of highly contaminated sites, particularly near sewage treatment works.

Main Results:

• A total of 8490 submerged plastic items were collected.
• The majority of intercepted items were plastic.
• Over 20% of litter items consisted of sanitary product components.
• Sites near sewage treatment works showed the highest contamination levels.

Conclusions:

• Freshwater catchments are a significant, often unseen, source of submerged plastic pollution entering marine environments.
• Sanitary product components represent a substantial portion of this plastic debris.
• Effective assessment and mitigation of marine plastic pollution must consider sub-surface flows from rivers and estuaries.