Beaches around Scapa Flow have a similar level of tiny plastic waste as industrialised waterways like the Clyde and Firth of Firth, new research has shown.

Sediment samples show that similar levels of microplastics were found in the northern body of water, despite its remoteness and Orkney's small population.

Scientists from Heriot-Watt University and Orkney Islands Council took more than 100 sediment samples from 13 locations around the Scapa Flow, and compared them to samples from the highly populated areas of the Clyde and Firth of Forth.

The results showed that microplastics -- tiny fragments of plastic from things like bags and clothing -- were present in all of the 13 samples.

Conservationists said that the find was "deeply concerning" and showed that it was vital to build on recent actions on plastic pollution.

The UK government has already announced plans to introduce legislation to ban the sale and manufacture of type of microplastic called microbeads: tiny beads in products such as toothpaste and shower gel which end up polluting seas because they are too small for water treatment plants to filter.

The Scottish Government recently announced plans for plastic cotton buds to be outlawed.

Meanwhile Western Isles Council has become the first local authority in Scotland to pledge to go plastic-straw free as part of calls for a wider ban.

Western Isles News Agency reported that the council said it was committed to phasing out plastic straws for civic catering as well as in all of its schools.

Dr Mark Hartl, associate professor of marine biology at Heriot-Watt, said the results of the Scapa Flow research was "surprising" given its location, sheltered within the Orkney Islands.

He said: "The fact that a relatively remote island has similar microplastic levels to some of the UK’s most industrialised waterways was unexpected, and points to the ubiquitous nature of microplastics in our water systems."

He called for a baseline record for all of the UK’s waters, "so that we can assess the impact of government policies that aim to reduce marine pollution, such as the microbead ban".

"At present we only have a patchwork of data from studies in Scotland and comparable North Sea locations.

“The growing amount of data regarding plastic litter contamination in the marine environment has led to the need for understanding the related risks not only to the health of marine life, but to humans as well: microplastics are working their way into our food chain," he said.

He said teams would be taking further samples in April as part of the Heriot-Watt’s Year of the Sea programme, which focuses on marine research.

Orkney Island Council said it will now also routinely test for microplastics during its annual sandy shore monitoring programme, with Heriot-Watt University providing analysis.

Friends of the Earth Scotland Head of Campaigns, Mary Church, said: "It is deeply concerning that microplastics are being found in high quantities in our marine environment so far from industrial hotspots, not that industry has any excuses for letting pollution escape. This research illustrates the plastic pollution epidemic that we've got ourselves into.

"It is vital that we change our attitude towards using and throwing away valuable resources if we are to reduce the damage we are wreaking on the our marine environment. Plastics are often only used for only a few minutes yet remain in our environment for generations.

"There is real public appetite for action on plastic pollution and recent environmental wins on plastic bags and cotton buds show that real change is achievable."

A spokeswoman for the Marine Conservation Society said it was "fascinating and crucial research".

She said: "We have long recognised the power of data as our 25 year running Beachwatch project has collected beach litter data from thousands of beaches showing important litter trends which we use to call for important policy changes such as the 5p carrier bag charge, the commitment to implement a Deposit Return System and the proposal for a ban on plastic cotton bud stems.

"The more data everyone can gather on both beach litter and microplastics will keep adding to that important evidence base to drive the policy changes our seas and shores need."

Jenni Kakkonen, a biologist with Orkney Islands Council’s Harbour Authority’s marine environmental unit, conducted the sampling in Orkney with her team.

Kakkonen, a part-time PhD student at Heriot-Watt’s International Centre for Island Technology (ICIT) on Orkney, said: “It’s important we keep an eye on the seas around us through research of this kind."

The findings of the research have been published in Marine Pollution Bulletin.