As much as half of some British beaches’ coarse sediments consist of human-made materials such as brick, concrete, glass and industrial waste, a study has found.
Climate breakdown, which has caused more frequent and destructive coastal storms, has led to an increase in these substances on beaches. Six sites on the Firth of Forth, an estuary on Scotland’s east coast joining the River Forth to the North Sea, were surveyed to better understand the makeup of “urban beaches”.
The researchers used a systematic search method to collect and analyse sediment from beaches at Torryburn, Ravenscraig, the Fife coastal path, Carriden, Granton and Prestonpans.
On Granton beach near Edinburgh, researchers from the University of Glasgow found evidence that up to half of the beach’s coarse sediments were from human-made materials. These sediments mostly derive from matter swept from land into the Forth by the erosion of coastal industrial sites and the dumping of waste.
This phenomenon is not unique to Scotland. On Crosby beach in Merseyside, waste from collieries and the blitz in the second world war now forms a large part of what is called sand. The Thames estuary’s sediments are also thought to be made up of a significant amount of human-made materials. On a sandy bank opposite Canary Wharf, littered bricks that have rounded over time are referred to as “Thames potatoes”.
Larissa Naylor, professor of geomorphology and environmental geography at the University of Glasgow and a co-author of the study, published in the journal Sedimentology, said: “Beaches are not static landforms – they change. How does a brick become a ‘Thames potato’? It’s not all just about marine plastics. People don’t necessarily know about things like this.”
She called for further research on urban coastal areas, saying this was vital for understanding how coastal management might evolve.
Across the surveyed beaches, an average of 22% of coarse sediments were found to be what the team called “anthropogenic geomaterial”. They said this warranted a new scientific classification: “anthropogenic sand and gravel” beaches. Scientists have said that as climate breakdown continues to accelerate coastal erosion, changes to the landscape could have an unpredictable effect on ecosystems.
“Research like this casts a new light on how human activity is affecting the natural world,” Naylor said.
