River Thames pollution, Arctic freshwater bulge
28 February 2012
This week in the Planet Earth Podcast: Sue Nelson goes to the River Thames in central London to find out why nitrate pollution has trebled since the 1930s. Later on, she talks to a researcher about an unusual freshwater bulge in the Arctic, and asks if we should be concerned. Finally, we hear a round-up of some of the news from the natural world.
Fifty years ago the River Thames was so polluted hardly anything lived in it. But changes in the law mean it's now considered one of the cleanest rivers running through a major city.
Despite that, scientists have recently discovered that fertilisers used in intensive agriculture since the Second World War have taken a surprising amount of time to find their way from farmland to the river. So its hard-won cleanliness is now at risk. Sue goes to the Thames to find out more.
Later, Sue talks to a scientist about her recent discovery of a worrying bulge of freshwater in the Arctic Ocean, and asks how it might affect us.
Click the play button above to listen now.
A full text transcript is available.
Finally, in a news round-up, we hear about the epic migration of a tiny songbird, how midges are more control of their direction than previously thought, and the love song of a long-extinct bush cricket.
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