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When is World Water Day in 2020: March 22nd, Sunday, February 29th of the lunar calendar.

The purpose of World Water Day is to arouse the public's awareness of water conservation and strengthen the protection of water resources. In order to meet the needs of people's daily life, commerce and agriculture for water resources, the United Nations has long been committed to solving the global water crisis caused by the rising demand for water resources. 1977 The "United Nations Water Conference" issued a serious warning to the whole world: water will soon become a profound social crisis, and the next crisis after the oil crisis will be water. 1993 65438+1October 18, the 47th UN General Assembly made a resolution to designate March 22nd as World Water Day every year.

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cause

Water is an indispensable and irreplaceable important natural resource and environmental factor for all life and social and economic development. However, the rapid development of population growth, industrial and agricultural production activities and urbanization in modern society has had a great impact on limited water resources and water environment. On a global scale, the pollution of water quality, the sharp increase of water demand and the unreasonable utilization caused by competing development among departments have further shortened water resources, worsened water environment, seriously affected social and economic development and threatened human welfare.

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Brief introduction of water

Water is a colorless and odorless liquid, and 72% of the earth's surface is covered with water. Although there is little water in the air, it is an important part of the air. The density of solid water (ice) (9 16.8kg/m3) is less than that of liquid water (999.84kg/m3), so the ice will float on the water surface, and the volume of water will increase slightly when it freezes. Water reaches its maximum density (999.97 kg/m3) at 3.98℃, while the maximum density of other liquids appears at the melting point. Water molecules are polar, that is, the positive and negative charge centers of water molecules do not coincide, which makes water a good solvent. Children have 80% water, the elderly have 50-60%, and normal middle-aged people have 70%.