A large amount of plastic debris was found in the River Thames during eel and mitten crab research in 2012.
Over a three month period between September to December 2012 8,490 submerged plastic items were trapped in eel fyke nets anchored to the riverbed at seven localities in the upper Thames estuary.
While sorting through the nets, the rubbish was set aside, bagged up and transported to the wet laboratory at the Museum for sorting into seven major litter categories.
The rubbish was catalogued by counting the number of items in each of the seven categories and recording the information on a data sheet based on the Ocean Conservancy’s International Coastal Clean-up data card. The proportion of rubbish in each category was calculated for the haul as a whole, and also for each of the seven locations within the upper Thames Estuary.
The results show that:
- the majority of litter items were some type of plastic
- more than 20% of the litter items were components of sanitary products
- the most contaminated sites were in the vicinity of sewage treatment works
While floating litter is visible, this study also demonstrates that a large volume of unseen submerged plastic is flowing into the marine environment. It is therefore important that this subsurface component is considered when assessing plastic pollution input into the sea.