Whole Earth geohydrologic cycle, from the clouds to the core: The distribution of water in the dynamic Earth system

Abstract

The whole Earth geohydrologic cycle describes the occurrence and movement of water from the clouds to the core. Reservoirs that comprise the conventional hydrologic cycle defi ne the exosphere, whereas those reservoirs that are part of the solid Earth represent the geosphere. Exosphere reservoirs thus include the atmosphere, the oceans, surface water, glaciers and polar ice, the biosphere, and groundwater. Continental crust, oceanic crust, upper mantle, transition zone, lower mantle and the core make up the geosphere. The exosphere and geosphere are linked through the active plate tectonic processes of subduction and volcanism. While the storage capacities of reservoirs in the geosphere have been reasonably well constrained by experimental and observational studies, much uncertainty exists concerning the actual amount of water held in the geosphere. Assuming that the amount of water in the upper mantle, transition zone, and lower mantle represents only 10%, 10%, and 50% of their storage capacities, respectively, the total amount of water in the Earth’s mantle (1.2 × 1021 kg) is comparable to the amount of water held in the world’s oceans (1.37 × 1021 kg). Fluxes between reservoirs in the geohydrologic cycle vary by ~7 orders of magnitude, and range from 4.25 × 1017 kg/yr between the oceans and atmosphere, to 5 × 1010 kg/yr between the lower mantle and transition zone. Residence times for water in the various reservoirs of the geohydrologic cycle also show wide variation, and range from 2.6 × 10−2 yr (~10 days) for water in the atmosphere, to 6.6 × 109 yr for water in the transition zone. *Corresponding author, Bodnar—rjb@vt.edu. Current addresses: Azbej—Deputy State Secretariat for Parliamentary Affairs, The Prime Minister’s Offi ce, 9/A. Marko u., Budapest, H-1055, Hungary; Becker—ExxonMobil Upstream Research Company, Houston, Texas, USA; Cannatelli—Dipartimento di Scienze della Terra, Universita di Napoli Federico II, Napoli, Italia; Fall—Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78713-8924, USA; Severs—Geology Program, Division of Natural Sciences and Mathematics, The Richard Stockton College of New Jersey, Galloway, New Jersey 08205, USA. Bodnar, R.J., Azbej, T., Becker, S.P., Cannatelli, C., Fall, A., and Severs, M.J., 2013, Whole Earth geohydrologic cycle, from the clouds to the core: The distribution of water in the dynamic Earth system, in Bickford, M.E., ed., The Web of Geological Sciences: Advances, Impacts, and Interactions: Geological Society of America Special Paper 500, p. 431–461, doi:10.1130/2013.2500(13). For permission to copy, contact editing@geosociety.org. © 2013 The Geological Society of America. All rights reserved. CELEBRATING ADVANCES IN GEOSCIENCE 1888 2013 Don White of the U.S. Geological Survey was one of the pioneers in characterizing the various natural water sources, and in 1957 he summarized his findings in a classic paper in the Bulletin of the Geological Society of America that included a highly-cited diagram showing different water reservoirs on Earth.