(1) Oxygen also occurs in the hydrosphere in the form of water, of which it makes up nearly 89% by weight, and in the Earth's crust.(2) Carbon returns to the hydrosphere when carbon dioxide dissolves in the oceans, as well as in lakes and other bodies of water.(3) It starts with the lithosphere (earth's crust and soil), goes on to atmosphere and hydrosphere (air and water), and ends up with the biosphere (living things).(4) Chlorine occurs abundantly in the Earth's crust and in the Earth's hydrosphere .(5) For example, the discovery of hydrothermal vents in the 1970s offered a clear proof of significant dynamic connections between the lithosphere, hydrosphere and biosphere.
