Водород (H)

1.40×103 milligrams per kilogram

1.08×105 milligrams per liter

Hydrogen is estimated to make up more than 90% of all the atoms three quarters of the mass of the universe! This element is found in the stars, and plays an important part in powering the universe through both the proton-proton reaction and carbon-nitrogen cycle. Stellar hydrogen fusion processes release massive amounts of energy by combining hydrogens to form helium.

Production of hydrogen in the U.S. alone amounts to about 3 billion cubic feet per year. Hydrogen is prepared by

▸ steam on heated carbon,

▸ decomposition of certain hydrocarbons with heat,

▸ reaction of sodium or potassium hydroxide on aluminum

▸ electrolysis of water, or

▸ displacement from acids by certain metals.

Liquid hydrogen is important in cryogenics and in the study of superconductivity, as its melting point is only 20 degrees above absolute zero.

Tritium is readily produced in nuclear reactors and is used in the production of the hydrogen bomb.

Hydrogen is the primary component of Jupiter and the other gas giant planets. At some depth in the planet's interior the pressure is so great that solid molecular hydrogen is converted to solid metallic hydrogen.

In 1973, a group of Russian experimenters may have produced metallic hydrogen at a pressure of 2.8 Mbar. At the transition the density changed from 1.08 to 1.3 g/cm3. Earlier, in 1972, at Livermore, California, a group also reported on a similar experiment in which they observed a pressure-volume point centered at 2 Mbar. Predictions say that metallic hydrogen may be metastable; others have predicted it would be a superconductor at room temperature.

Measurements of relative 2H abundances are used to determine the breeding grounds of many species of migrant songbirds. These species of songbirds only grow their feathers before migration, and they grow them on or close to their breeding grounds. Therefore, the isotopic composition of a bird’s feathers correlates to the isotopic composition of the growing season’s precipitation [18] [18] Z. D. Sharp, V. Atudorei, H. O. Panarello, J. Fernández, C. Douthitt. J. Archaeolog. Sci.30, 1709 (2003).[18] Z. D. Sharp, V. Atudorei, H. O. Panarello, J. Fernández, C. Douthitt. J. Archaeolog. Sci.30, 1709 (2003)., [19] [19] K. A. Hobson. Oecologia120, 314 (1999).[19] K. A. Hobson. Oecologia120, 314 (1999)., [20] [20] K. A. Hobson, L. I. Wassenaar. Oecologia.109, 142 (1996).[20] K. A. Hobson, L. I. Wassenaar. Oecologia.109, 142 (1996)..

Measurements of relative 2H abundances of human hair samples collected at archeological sites are used to determine the geographic region in which a subject lived based on the hydrogen isotopic composition of the water they drank. This is possible because hair stores a daily record of the hydrogen isotopic composition of intake water, which correlates to local meteoric water [18] [18] Z. D. Sharp, V. Atudorei, H. O. Panarello, J. Fernández, C. Douthitt. J. Archaeolog. Sci.30, 1709 (2003).[18] Z. D. Sharp, V. Atudorei, H. O. Panarello, J. Fernández, C. Douthitt. J. Archaeolog. Sci.30, 1709 (2003)., [21] [21] T. B. Coplen, H. Qi. Forensic Sci. Int.266, 222 (2016).[21] T. B. Coplen, H. Qi. Forensic Sci. Int.266, 222 (2016)..