Geochemistry

Geochemistry is the science or study of the chemistry of the earth. Geochemists who practice this science are interested in the origin of chemical elements, their evolution, the classes and many divisions of minerals and rocks and how they are created and changed by earth processes, and the circulation of chemical elements through all parts of the earth including the atmosphere and biological forms.

The circulation of elements in nature has many practical applications. Understanding the distribution of chemical isotopes and their stability (or instability) helps in fields as varied as age-dating in archaeology and medical uses of radioactive isotopes. Some significant chemical elements like carbon, phosphorus, nitrogen, and sulfur have geochemical cycles that are indicators of environmental contamination or the need to rotate crops in fields.

Geochemistry has many subdivisions. Inorganic geochemistry explains the relationships and cycles of the elements and their distribution throughout the structure of the earth and their means of moving by thermodynamics and kinetics. Exploration geochemistry (also called geochemical prospecting) uses geochemical principles to locate ore bodies, mineral fields, groundwater supplies, and oil and gas fields. Organic geochemistry uses the chemical indicators associated with life forms to trace human habitation as well as plant and animal activity on Earth. It has been important in understanding the paleoclimate, paleooceanography, and primordial life and life's evolution. Sedimentary geochemistry interprets what is known from hard rock geochemistry in soil and other sediments and their erosion, deposition patterns, and metamorphosis into rock. Environmental geochemistry is the newest branch of the science and came into prominence in the 1980s when environmental concerns made the tracking of chemicals in organic tissues, groundwater, surface water, the marine environment, soil, and rock important to scientists, engineers, and government agencies responsible for the public's well-being.