A UCL-led team suggests that the lovely brown hue of the Thames may be indicative of a more natural river

When Ray Davies penned the lyrics to Waterloo Sunset in 1967, the Thames was indeed filthy. Decades of heavy industry and poor pollution control had rendered the river devoid of animal life. These days, the river is home to over 120 species of fish, herons and cormorants are a common sight, and the Thames is among the cleanest metropolitan rivers in the world. Such a turnaround is something we all should be proud of as Londoners, but most people I talk to still think of the river as a smelly, polluted environment. It’s gloopy brown colour probably doesn’t help.

But now scientists at UCL’s Environmental Change Research Centre and the US Environmental Protection Agency say that rivers, brooks and ponds across the northern hemisphere are increasingly turning brown not through pollution, but because of dissolved organic matter. According to John Stoddard of the EPA:

‘The most important driver has actually been the major reduction in acid rain since the 1970s. As acidity and pollutant concentrations in the soil fall, carbon becomes more soluble, which means more of it moves into our lakes and rivers and more can be exported to the oceans.’

The full study is published in this week’s Nature, but Science News deserve a link for the cheeky headline ‘Don’t judge a brook by its colour’.

Image taken from hey mr glen’s Flickr photostream.