Quick Water Reference
WATER
A simple chemical compound whose state (liquid, solid or gas) depends on temperature and pressure.
Water is a simple chemical compound whose state (liquid, solid or gas) depends on the temperature and pressure conditions. It is liquid under ambient conditions (20°C and 1 bar ). At ambient pressure (1 bar), it becomes a gas at 100°C and a solid at 0°C. Its chemical formula is H2O, which means that each water molecule is made up of one oxygen atom and two hydrogen atoms.
DRINKING WATER
Water which must meet a certain number of criteria in order to be drunk by humans without endangering their health.
Drinking water is water that can be drunk by humans without endangering their health. For this it must comply with a number of standards set by WHO and contain a maximum of 50 mg of nitrates per litre, less than 0.1 mg of pesticides and less than 0.25 mg of lead, etc. Below these thresholds it is assumed that the presence of these pollutants has no effect on humans.
FRESH WATER
Continental water, both underground and on the surface, containing few dissolved salts and generally used to produce drinking water.
Fresh water is water found on the surface of continents (surface water) and underground (groundwater). It accounts for 3% of the total amount of water on Earth and is mainly present in the form of ice. Most of the rest is underground in groundwater tables which in some cases are very deep. Low in mineral salts , fresh water is generally used to produce drinking water .
WATER POLLUTION
The direct or indirect introduction into water, essentially by humans, of harmful substances, microorganisms or heat.
Most water pollution is the result of the introduction into water by humans of heat (nuclear power stations), microorganisms (untreated waste) and various substances that have negative effects on ecosystems, health and water-based activities (swimming, diving, fishing, etc.). It effects underground and surface fresh water , the oceans and rainwater.
Most pollutants that affect water come from human activity: industrial waste ( heavy metals , hydrocarbons , hot water, radioactive elements, etc.), agricultural effluents ( pesticides , veterinary products, nitrates , phosphorus, bacteria , etc.) and domestic effluents (soaps, organic waste, viruses and bacteria, etc.). The Earth's atmosphere also contains pollutants that can contaminate the soil and water when it rains. However, certain natural phenomena can contribute to water pollution. When groundwater comes into contact with mineral deposits this can result in unusually high concentrations of heavy metals. Events such as volcanic eruptions and underwater spills of hydrocarbons can also cause marine pollution.
WATER CYCLE
The natural circuit of water in its different states (a liquid, gas and solid) between the oceans, atmosphere and continents.
The water cycle is the circuit that water follows in nature: surface water evaporates due to the effect of the sun and rises into the atmosphere where it cools, condenses into clouds and produces precipitation (rain, snow, etc.) Some of it evaporates, some infiltrates into the ground and feeds water tables and some feeds glaciers. The rest returns to the sea along watercourses.
The volume of water on Earth is constant (1,386,000,000 km3). The oceans contain 97% of it and 3% is fresh water . Glaciers and the polar ice caps store more than two thirds of the Earth's fresh water and groundwater accounts for a little less than a third. The rest (0.04%) is found in lakes, marshes and rivers, and a tiny proportion is in living things. As for water vapour, its quantity in the air varies but remains less than 0.001% of the total water volume. Changes in the state of water play a major part in the climate because evaporation absorbs a lot of heat whereas condensation releases heat. Water vapour and clouds are responsible for 72% of the greenhouse effect , with the remaining 28% being due to other greenhouse gases such as carbon dioxide and methane.
EARTH'S ATMOSPHERE
Envelope made up of gas and microscopic dust that surrounds certain planets, including the Earth.
Our atmosphere is made up of several layers of gas and suspended particles held to the surface of the Earth. Its total thickness is around 500 kilometres and its density and temperature fall as altitude increases. Only the lowest layer of the atmosphere (15 kms) holds living creatures. It is swept by air currents that cause climatic phenomena.
The Earth’s atmosphere is mainly made up of two gases. The most plentiful are nitrogen (78%), followed by oxygen (21%), the gas we breathe, produced by plants. Among the remaining gases, some play a vital role for living organisms, especially carbon dioxide (0.035%), one of the gases responsible for the greenhouse effect that keeps our temperatures mild ; steam (0 to 4 % in volume), which produces clouds and precipitation; and finally ozone (0.000012%), which absorbs harmful ultraviolet rays. One m3 of atmosphere at sea level has a mass of 1 kg, a thousand times less than the same volume of water.
THE SYMBOLISH OF WATER
Water unceasingly changes shapes and transforms itself. It is thus a model out of which everything can be born. Water, consequently, becomes a symbol of fertility that can be found in all the myths and all the religions. Beings and things are born of water. Water also possesses medicinal virtues. Some waters are recognized miraculous powers capable of healing the bodies.
It is also a source of purification. Purification for the individual beings but also for the whole of mankind. The Flood is a founding episode in numerous civilisations. Among Australia’s Aborigenes, a giant frog is said to have swallowed the Earth’s water to release it only when the other animals, dying with thirst, made it burst out laughing. The Flood in a re-creation of the world. One emerges from water in order to be reborn.
Water, Source of Life: Click here
VIRTUAL WATER
An economic concept used to describe the volume of water required to produce food and/or manufacture objects.
Invented in the 1990s, this concept is a way of calculating the actual quantity of water used by a country, its "water footprint", which represents the total amount of water it consumes, increased by its imports and reduced by its exports of virtual water. The trade in food crops and other goods creates a virtual flow of water between the countries that produce and export (such as North America, the world's biggest exporter), and countries that import and consume these goods (such as Germany). A country that is short of water, such as Saudi Arabia, imports products that require a lot of water rather than producing them itself, thereby saving its water resource. On a global level this trade causes dependencies between countries.
It takes approximately 1,500 litres of water to produce one kilo of wheat, 4,500 l for 1 kg of rice and 100,000 litres for 1 kg of aluminium.
Virtual water reference: click here
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