Hydrosphere

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The Earth captured in the Pacific Ocean side

The hydrosphere (from

Ancient Greek ὕδωρ (húdōr) 'water', and σφαῖρα (sphaîra) 'sphere')[1][2] is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Although Earth's hydrosphere has been around for about 4 billion years,[3][4] it continues to change in shape. This is caused by seafloor spreading and continental drift, which rearranges the land and ocean.[5]

It has been estimated that there are 1.386 billion cubic kilometres (333 million cubic miles) of water on Earth.

seas, lakes, rivers and streams, wetlands, glaciers, ice and snow cover on Earth's surface; vapour, droplets and crystals in the air; and part of living plants, animals and unicellular organisms of the biosphere. Saltwater accounts for 97.5% of this amount, whereas fresh water accounts for only 2.5%. Of this fresh water, 68.9% is in the form of ice and permanent snow cover in the Arctic, the Antarctic and mountain glaciers; 30.8% is in the form of fresh groundwater; and only 0.3% of the fresh water on Earth is in easily accessible lakes, reservoirs and river systems.[9]

The total mass of Earth's hydrosphere is about 1.4 × 1018

tonnes, which is about 0.023% of Earth's total mass. At any given time, about 2 × 1013 tonnes of this is in the form of water vapor in the Earth's atmosphere (for practical purposes, 1 cubic metre of water weighs 1 tonne). Approximately 71% of Earth's surface, an area of some 361 million square kilometres (139.5 million square miles), is covered by ocean. The average salinity of Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5%).[10]

History

According to Merriam Webster, the word hydrosphere was brought into English in 1887, translating the German term hydrosphäre, introduced by Eduard Suess.[11]

Water cycle

Main article: Water cycle

The water cycle refers to the transfer of water from one state or reservoir to another. Reservoirs include

insolation), and gravity cause the transfer from one state to another over periods from hours to thousands of years. Most evaporation comes from the oceans and is returned to the earth as snow or rain.[12]: 27 Sublimation refers to evaporation from snow and ice. Transpiration refers to the expiration of water through the minute pores or stomata of trees. Evapotranspiration is the term used by hydrologists in reference to the three processes together, transpiration, sublimation and evaporation.[12]

life to evolve on Earth
.

Human activity has had an impact on the water cycle. Infrastructure, like dams, have a clear, direct impact on the water cycle by blocking and redirecting water pathways. Human caused pollution has changed the biogeochemical cycles of some water systems, and climate change has significantly altered weather patterns.[13] Water withdrawals have exponentially increased because of agriculture, state and domestic use, and infrastructure.[14]

Recharging reservoirs

According to Igor A. Shiklomanov, it takes 2500 years for the complete recharge and replenishment of oceanic waters, 10,000 years for permafrost and ice, 1500 years for deep groundwater and mountainous glaciers, 17 years in lakes, and 16 days in rivers.[9]

Specific fresh water availability

"Specific water availability is the residual (after use) per capita quantity of fresh water."[9] Fresh water resources are unevenly distributed in terms of space and time and can go from floods to water shortages within months in the same area. In 1998, 76% of the total population had a specific water availability of less than 5.0 thousand m3 per year per capita. Already by 1998, 35% of the global population suffered "very low or catastrophically low water supplies," and Shiklomanov predicted that the situation would deteriorate in the twenty-first century with "most of the Earth's population living under the conditions of low or catastrophically low water supply" by 2025. Only 2.5% of the water in the hydrosphere is fresh water and only 0.25% of that water is accessible for our use.

Human impact

The activities of modern humans have drastic effects on the hydrosphere. For instance, water diversion, human development, and pollution all affect the hydrosphere and natural processes within. Humans are withdrawing water from aquifers and diverting rivers at an unprecedented rate. The

rivers are free-flowing due to the extensive use of dams, levees, hydropower, and habitat degradation.[16] Excessive water use has also caused intermittent streams to become more dry, which is dangerous because they are extremely important for water purification and habitat.[17] Other ways humans impact the hydrosphere include eutrophication, acid rain, and ocean acidification. Humans also rely on the health of the hydrosphere. It is used for water supply, navigation, fishing, agriculture, energy, and recreation.[18]

See also

Notes

  1. ^ According to the planetary geologist, Ronald Greeley, "Water is very common in the outer solar system."[citation needed] Europa holds more water than earth's oceans.

References

  1. Perseus
  2. Perseus
  3. ^ Encyclopædia Britannica, 'Hydrosphere': https://www.britannica.com/science/hydrosphere/Origin-and-evolution-of-the-hydrosphere
  4. doi:10.1016/j.crte.2007.09.006
    .
  5. ^ "Our Changing Planet: an Introduction to Earth System Science and Global Environmental Change." Our Changing Planet: an Introduction to Earth System Science and Global Environmental Change, by Fred T. Mackenzie, 2nd ed., Pearson Education, 2011, pp. 88–91.
  6. ^ Where is Earth's water?, United States Geological Survey.
  7. NOAA National Geophysical Data Center, Boulder, CO
    , 2010.
  8. ^ Water in Crisis: Chapter 2, Peter H. Gleick, Oxford University Press, 1993.
  9. ^ a b c d World Water Resources: A New Appraisal and Assessment for the 21st Century (Report). UNESCO. 1998. Archived from the original on 27 September 2013. Retrieved 13 June 2013.
  10. ISBN 0-8493-2391-6
    .
  11. ^ "Definition of HYDROSPHERE".
  12. ^
    OCLC 43365804., revised 2003|Governor General's Award
    (1999)
  13. PMID 11344294
    .
  14. PMID 24344275
    .
  15. doi:10.1038/scientificamericanearth0309-32
    . Retrieved March 26, 2020.
  16. ^ Carrington, Damian (May 8, 2019). "Only a third of world's great rivers remain free-flowing, analysis finds". The Guardian. Retrieved March 26, 2020.
  17. S2CID 236998854
    .
  18. ^ Klige, R. K. (2014). Global Studies Encyclopedic Dictionary. Value Inquiry Book Series. pp. 267–269.

External links

Look up hydrosphere in Wiktionary, the free dictionary.
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