'Citizen scientists' in clean-up of plastic bottles along the Thames

Thousands of plastic bottles will be collected from the shoreline of the Thames in London this weekend, the biggest mapping project ever to be attempted on the river.

Last year "citizen scientists" collected 2,500 bottles from 11 beaches helping to build an understanding of litter distribution in waterways.

This year members of the public will visit 20 different sites as part of the Big Bottle Count and the #OneLess campaign working to cut the amount of ocean pollution.

The number of volunteers has risen in recent years with 100 people trained up by charity Thames21 annually.

The charity says their citizen scientists are "the last line of defence in the battle against the plastic tide, and stopping it from reaching the sea".

Chris Coode, deputy chief executive of Thames21, told Sky News volunteer involvement is hugely significant.

"They have local knowledge and they know their local site really well… if we have a good network of citizen scientists we can build up a huge picture of data.

"We can have many more people capturing much more data than you could have with a paid scientist.

"…this is the key thing with citizen science if you can support them properly and create a method that is scientifically robust, so the data you are collecting actual scientists can use, then you can pass that information onto scientists who can analyse it.

"Then you're actually capturing a lot more data than you would otherwise be able to do through conventional science means.

"Also your citizen scientists become ambassadors for the cause."

The Big Bottle Count aims to remove plastic from the Thames but also to investigate where the bottles are coming from, where they are ending up and how their entry into the river can be stopped.

The #OneLess campaign is "working to create a refill revolution in London, creating a culture where using a refillable water bottle is the norm".

According to Thames21 the average adult in London buys 175 bottles of water a year.

The campaign and project coincides with an art installation tour of the banks of the river which showcases plastic retrieved from the Thames over a one-year period.

Artist Maria Arceo decided to do the project when she found a pair of sandals on the side of the river which are believed to be 100 years old.

Maria says she began questioning how long plastic would be in our oceans if leather could last a century in water.

The installation is called Future Dust and is in the shape of a giant footprint.

"This is only a fraction of what is out there," she said. "If you can multiply what I find if I just do one beach each day all over the Thames then what I pick up in one beach will be multiplied by all those other beaches.

"…and compared to all rivers around the world in comparison this is a clean river so I want people to realise just because it looks clean it doesn't mean it is. We need to change the way we behave."

:: You can find out more about Sky Ocean Rescue and get involved by visiting the campaign's website.