The mantle-water research is fairly new, with this report from 2017:
"There’s as much water in Earth’s mantle as in all the oceans"
<https://www.newscientist.com/article/2133963-theres-as-much-...>
The USGS detail pages are based on a 1993 publication, Igor Shiklomanov's chapter "World fresh water resources" in Peter H. Gleick (editor), Water in Crisis: A Guide to the World's Fresh Water Resources (Oxford University Press, New York).
<https://www.usgs.gov/special-topics/water-science-school/sci...> and <https://www.usgs.gov/special-topics/water-science-school/sci...>
The mantle-water research is fairly new, with this report from 2017:
"There’s as much water in Earth’s mantle as in all the oceans"
<https://www.newscientist.com/article/2133963-theres-as-much-...>
The USGS detail pages are based on a 1993 publication, Igor Shiklomanov's chapter "World fresh water resources" in Peter H. Gleick (editor), Water in Crisis: A Guide to the World's Fresh Water Resources (Oxford University Press, New York).
<https://www.usgs.gov/special-topics/water-science-school/sci...> and <https://www.usgs.gov/special-topics/water-science-school/sci...>