A composer marinated his music in oil slicks, duckweed and decaying leaves in a bizarre artistic project to raise awareness of London’s polluted rivers.

Rob St John soaked tape loops of field recordings taken by the River Lea, as well as new music he composed inspired by it, in the water itself for his project Surface Tension.

The Lancastrian musician, artist and writer left it in tubs of duckweed, decaying leaves and oil slicks for a whole month, with the aim of processing the recordings in a way echoing the Lea’s water pollution.

The eery result will be played in a gallery in Hackney Wick, where negatives of photographs he took which were given the same river water treatment will be on show.

The unusual project was commissioned last summer by Ben Fenton, co-ordinator of the ‘Love the Lea’ project run by waterway charity Thames21.

He asked Mr St John to design a project to creatively explore and document pollution along the River Lea, drawing from both art and science.

East London’s rivers are some of the most polluted in Britain, running with high levels of e-coli sewage bacteria, waste water from people’s homes and poisonous oils and chemicals from the roads.

The polluted water flows down the Lea Valley from Broxbourne into Hackney, killing fish and destroying ecosystems.

Mr Fenton said: “Rob’s work portrays the plight of the Lea through an inspiring mix of words, photos and music – we hope this to engage a new audience to support our Love the Lea and make a positive difference for this amazing river.”

Mr St John added: “The name Surface Tension comes from the variety of different ‘surfaces’ in the Lea Valley – from the polluted river surface overgrown with neon green weeds and gleaming with oil slicks, over rusting and crumbling brick and metal surfaces, to the shape-shifting role of environmental sound in telling us about people, places and the environment.

“Surface Tension is an album that is intricate, layered and accessible and it will hopefully contribute to raise awareness of the pollution problems facing the River Lea.”

Surface Tension will be on show at Stour Space, Roach Road, Hackney Wick throughout April.