A second leak at the Shell oil platform in the North Sea is proving harder to stop than the first.

A Chinese protest against a chemical factory was one of the largest in three years — at least 12,000 people — and may herald a shift towards more public action in the country.

Philadelphia Mayor Michael Nutter is exchanging ideas with leaders in Rio about greening their cities.

How our tricksy brains are keeping us from drinking cleaned wastewater: "It is quite difficult to get the cognitive sewage out of the water, even after the real sewage is gone," says one psychologist.

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Everything you ever wanted to know about beaches, and more.