Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

In this photo taken June 3, 2009, a female North Korean soldier looks out from behind a barbed-wire fence around a camp on the North Korean river banks across from Hekou, northeastern China's Liaoning province. North Korea's top court has convicted two U.S. journalists, and sentenced them to 12 years in labor prison, the country's state news agency reported Monday. (Photo by Ng Han Guan/AP Photo)

These pictures reveal the crumbling ruins of the famed Grand Orient Express, now hollowed-out and almost reduced to rubble. There are only a couple of the trains, launched in 1883, left in the world. This example stands dormant in Belgium, untouched from its last voyage in the winter of 2009. Rusty ceilings, moth-eaten seats and tattered floors capture its level of decay. A Rotterdam-based urban photographer Brian Romeijn managed to snap these pictures while exploring the area. (Photo by Brian Romeijn/IMP Features)

A student of the department for aritificial intelligence at the Freie Universitaet Berlin steers a converted Dodge minivan remotely with an iPhone during a demonstration at Tempelhof Airport on November 2, 2009 in Berlin, Germany. The car, whose design was led by professor Raul Rojas, is outfitted with a variety of laser sensors, GPS antennae and computers. (Photo by Sean Gallup/Getty Images)

A three-week-old chihuahua puppy named Tom Thumb poses in a tea cup on April 7, 2009 in Renton, Scotland. The pup, which measures eight inches long, is thought to be one of the smallest dogs born in the UK and is just two inches short of a world record. (Photo by Jeff J Mitchell/Getty Images)

A British inspired Transformer, made from original bus parts is displayed in front of Tower Bridge on November 28, 2009 in London, England. Twitter fans voted to see a London “bendy” bus made into a Transformer to celebrate the DVD & Blu-ray release of “Transformers: Revenge of The Fallen”. (Photo by Marco Secchi/Getty Images for Paramount Home Entertainment)

Crowd reaction outside the court for the Dr. Conrad Murray trial verdict on November 7, 2011 in Los Angeles, California. Murray was convicted in the 2009 death of pop singer Michael Jackson from an overdose of the powerful anesthetic propofol. Sentencing will take place November 29. (Photo by Toby Canham/Getty Images)

Visitors of the world's longest tree top walk between the trees of the Bavarian forest on November 6, 2009 in Neuschoenau, Germany. The path, 1300 meters long and in 8 to 25m height, winds up to an impressive tower with a height of 44 meters. The wooden construction is integrated into the forest and delivers a natural experience. (Photo by Miguel Villagran/Getty Images)