A Syrian refugee girl plays outside a tent at a refugee camp in Zahle in the Bekaa valley November 18, 2014. In October, Lebanon, which has the highest per capita concentration of refugees in the world at one in four residents, said it could not cope with more than one million Syrians and has asked for funds to help look after them. (Photo by Mohamed Azakir/Reuters)

Nepalese women farmers spray mud water at each other while planting rice in a paddy field during the National Paddy Day in the village of Jitpur in Kathmandu, Nepal, 30 June 2015. On this day, known as Asar Pandra, farmers begin the annual rice planting season and mark the day with various festivities such as preparing rice meals with muddy water, spreads mud among farmers. The Mud being a symbol for a prosperous season. The agricultural sector contributes about 60 per cent to Nepal's gross domestic product. (Photo by Narendra Shrestha/EPA)

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Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of the East African Rift. The lake is fed by the Southern Ewaso Ng'iro River and also by mineral-rich hot springs. It is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving concentrations of salt and other minerals, notably sodium carbonate (natron).

Farmers plant rice seedlings in a paddy in Karanganyar, near Solo, Central Java, Indonesia in this April 13, 2016 photo taken by Antara Foto. (Photo by Maulana Surya/Reuters/Antara Foto)

“Window of Autumn” by Hasan Baglar taken in Nicosia, Cyprus, which has come first in the All About Plants Section for the RHS Photographic Competition 2019. (Photo by Hasan Baglar/RHS/PA Wire Press Association)

A tower belonging to the Abengoa solar plant at the Solucar solar park is seen in Sanlucar la Mayor, Spain on October 1, 2018. (Photo by Marcelo del Pozo/Reuters)

The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine, which was under the direct jurisdiction of the central authorities of the Soviet Union. The Chernobyl disaster is the worst nuclear power plant accident in history in terms of cost and resulting deaths, and is one of only two classified as a level 7 event (the maximum classification) on the International Nuclear Event Scale (the other being the Fukushima Daiichi nuclear disaster in 2011). Photo: Graffiti of a crying baby on a wall, Chernobyl Power Plant, Chernobyl, Ukraine. (Photo by Hans Neleman/Getty Images)

An explosion at a petrochemical plant is seen in Rizhao, Shandong province, July 16, 2015. According to Xinhua News Agency, a fire broke out after the explosion, which was caused by a liquified hydrocarbon leak at the plant, on Thursday morning. There was no report of casualties yet. (Photo by Reuters/China Daily)