USGS RESEARCH ON THE GEOCHEMISTRY OF NATURAL WATERS AT MENLO PARK, CALIFORNIA

By D.V. Vivit

The U.S. Geological Survey (USGS) pioneered research on dissolved substances in natural waters. In the early 20th century the USGS conducted extensive studies of stream-water chemistry in cooperation with the Reclamation Service (now U.S. Bureau of Reclamation). The first edition of “The data of geochemistry” was published as USGS Bulletin 330 in 1908 and was revised and enlarged through five editions by 1924. By the mid-1950s, when the USGS established its Regional Center at Menlo Park, California, water chemistry had emerged as a recognized scientific field. In 1959, research chemist John David Hem published the landmark USGS Water-Supply Paper 1473, “Study and interpretation of the chemical characteristics of natural water”. Though not marketed as a textbook, Water-Supply Paper 1473 has been and is used extensively as one throughout the scientific world. With this text – along with the second and third editions published in 1970 and 1985 – Hem himself taught water-chemistry principles to multitudes of USGS scientific and technical staff at the USGS National Training Center in Denver, CO.

John Hem’s arrival at the Western Regional Center in 1963 followed 24 years of previous service and experience with USGS operations and research at the Washington, D.C., headquarters; in the Arizona and New Mexico District offices; and at the Regional Center in Denver, Colorado. Joining the newly-formed WRD Research Program at Denver in 1953, he initiated research projects which studied the geochemical behaviors of iron and manganese in low-temperature aquatic systems. The iron and manganese investigations continued at Menlo Park, and experiments with the hydrolysis of aluminum and the synthesis of clay silicates began.

The innovative experiments, conducted both in the field and laboratory, had significant implications for understanding the movement of the chemical elements silicon, iron, manganese and aluminum in the natural environment: from the solid phase (i.e. silicate rocks) into the hydrologic realm by dissolution (hydrolysis) of rock minerals caused by chemical weathering and back into the solid phase as clay silicates (such as kaolinite and halloysite) produced from the precipitation of amorphous oxyhydroxides. Toxic forms of heavy metals and other transition metals such as cadmium, cobalt, lead, mercury, nickel, and zinc are removed from aqueous systems by the co-precipitation of the respective metal oxyhydroxides with those of iron, manganese, aluminum, and silica.

Chemical processes encountered and analyzed in experiments with equilibrium and non-equilibrium (steady-state) aquatic systems included oxidation-reduction (redox) and disproportionation reactions, dissolution and nucleation kinetics, and autocatalysis. Hem’s qualifications in water-chemistry research also enabled him to write authoritatively about sulfur as a pollutant in natural waters.

The hydrogeochemical knowledge acquired at Menlo Park impacted research and development world-wide in the areas of groundwater recharge of aquifers; treatment of potable water and waste water; chemical remediation of polluted ground and surface waters; radioactive waste disposal; rock and mineral chemical-weathering processes; soil fertility; preservation of aquatic and marine ecosystems; and human health.

During his 56-year career with the USGS, John Hem authored or co-authored over 150 publications. Co-investigators who worked at one time or another on Hem’s project in Menlo Park, prior to his death in 1994, included W.L. Polzer, C.E. Roberson, C.J. Lind, R.W. Smith, D.W. Brown, J.L. Bersillon, R.B. Barnes, H.M. May, and D.V. Vivit.

John Hem’s legacy is honored by a named award. The “John Hem Excellence in Science and Engineering Award” is presented annually by the National Ground-Water Association. This award acknowledges an individual who has made a significant, recent (within five years) scientific or engineering contribution to the understanding of ground water.

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