What is the hydrosphere?
According to the definition as used in physical geography, the hydrosphere is the collective mass of water found on, above, and below the Earth’s surface. It includes both the world’s marine and freshwater resources and encompasses oceans, rivers, lakes, glaciers, polar ice caps, clouds, groundwater such as aquifers and all other sources of water. ‘water. The presence of the vast hydrosphere distinguishes planet Earth from other planets in the solar system and is one of the main factors responsible for sustaining life observed on Earth.
Distribution of water in the hydrosphere
Oceans account for 97.25% of the total water mass on the Earth’s surface, followed by ice caps and glaciers (2.05%), deep groundwater (0.38%) and shallow groundwater. deep (0.30%). Lakes and rivers, the moisture trapped in the soil and the water vapor in the atmosphere, as well as the water contained in the living organisms of the biosphere, are the other constituents of the terrestrial hydrosphere.
Origin of the hydrosphere
The water content of the Earth is relatively much higher than that of any of the other known planetary bodies of similar size. Although the “outgassing” of water vapor from the Earth’s interior is considered one of the sources of water on this planet, it cannot explain the extremely high volumes of Earth’s water resources. . According to the most commonly accepted scientific theory on the subject, the water on Earth was added by the collision of this planet with several asteroids, comets and other water-rich planetary bodies at the time of the formation of the Earth.
The water cycle
The waters of the hydrosphere are never static, but rather are in constant motion which leads to the exchange of water between the Earth’s oceans, rivers and lakes, the atmosphere, the lithosphere and the biosphere. This movement of water in the Earth’s hydrosphere is known as the “water cycle” or “hydrological cycle”. Evaporation exceeds precipitation over the oceans, with much of the evaporated water being transported to land where it condenses and precipitates as rain or snow, then seeps underground or runs off in rivers or is collected in ice caps and glaciers. Runoff from melting snow from ice caps and glaciers enters rivers and river and groundwater waters, eventually flowing back into the oceans, completing the water cycle. Water absorbed by plants in the biosphere from groundwater is added to the atmosphere via the transpiration of their leaves, which again becomes part of the water cycle.
Life and the hydrosphere
Life on Earth without the hydrosphere is unimaginable. An active hydrosphere is necessary for all life forms to exist, multiply and grow. All vital biochemical reactions require water as a solvent. The hydrosphere water cycle is responsible for providing an abundant supply of clean, fresh water to all living things on Earth. The extreme importance of the hydrosphere in sustaining life is reflected in the fact that the search for life on other planets always begins with a search for water on those same planets.
Threats to the hydrosphere
Currently, the activities of modern human society continue to have an extremely detrimental effect on the earth’s hydrosphere. Eutrophication, acid rain and global warming are the three main threats to the hydrosphere in the modern world, and each is explained below.
Human activities lead to the excessive accumulation of nutrients (phosphate and nutrients from fertilizer runoff) and organic matter (from sewage) in the hydrosphere, triggering an explosion of algae and plankton, making the waters very troubles and killing fish and other aquatic species in the depths of water bodies due to low oxygen availability. This phenomenon is called eutrophication.
Acid precipitation is generated by the emission of sulfur dioxide and nitrogen oxides into the atmosphere by the combustion of fossil fuels. The precipitation that falls is acidic in nature and corrodes buildings and constructions, and makes the world’s water resources acidic and therefore unsuitable for life, and increases the leaching of other metals into the acidic water.
Although acid precipitation and eutrophication activities are localized to many water bodies around the world, greenhouse gas emissions affect the entire hydrosphere of the world as a whole. Rising temperatures are increasing the rate of evaporation from the world’s rivers, oceans and lakes, melting glaciers and polar ice caps, raising sea levels around the world and creating global disruption and imbalance within the Earth’s hydrosphere and other Earth systems. depends on it.