A Syrian boy receives treatment at a hospital in the regime-held part of Aleppo on October 13, 2016. Syrian state television said four children were killed by rebel rocket fire on a school in a western regime-held neighbourhood. (Photo by George Ourfalian/AFP Photo)

A woman takes a picture of a Maserati's SUV model Levante during the Auto China 2016 show in Beijing, China April 25, 2016. (Photo by Kim Kyung-Hoon/Reuters)

Clearing skies await a tripod-toting photographer looking for a spot to capture the early-morning light at Portland Head Light, Thursday, January 17, 2013, in Cape Elizabeth, Maine. (Photo by Robert F. Bukaty/AP Photo)

An Indian villager braving strong winds and rain walk to a safer place, in village Podampeta, in Ganjam district about 200 kilometers (125 miles) from the eastern Indian city Bhubaneswar, India, Saturday, October 12, 2013. Strong winds and heavy rains pounded India's eastern coastline Saturday, as hundreds of thousands of people took shelter from a massive, powerful Cyclone Phailin expected to reach land in a few hours. (Photo by Biswaranjan Rout/AP Photo)

Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)

Revelers jump on a rainbow painted crosswalk in Church Street, Toronto's LGBT neighbourhood, before “WorldPride”, a gay pride parade, in Toronto, June 29, 2014. Toronto is hosting WorldPride, a week-long event that celebrates the lesbian, gay, bisexual and transgender (LGBT) community. (Photo by Mark Blinch/Reuters)

A model has makeup applied backstage prior to Lebanese designer Zuhair Murad fashion show held during the Haute Couture Fall/Winter 2014-2015 fashion collections in Paris July 10, 2014. (Photo by Philippe Wojazer/Reuters)

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)