Geochemistry

Abstract

Geochemistry is a subdiscipline of chemistry whose objective is understanding the processes occurring on and in the earth, its evolution, and its cosmic environment, and to using that understanding to better the human condition. It naturally divides into (a) low‐temperature or environmental geochemistry, focused on processes at or near the earth's solid surface, including the “critical zone,” the oceans, and the atmosphere, and (b) high‐temperature geochemistry focused on processes such as hydrothermal ore deposition, magmatism, and metamorphism. Isotope geochemistry takes advantage of naturally occurring variations in the isotopic composition of elements resulting from natural, nuclear, and chemical processes to further understand earth processes, both in the near‐surface environment and the earth's deep interior. Geochemistry has greatly enhanced our knowledge of nucleosynthesis, solar system formation, plate tectonics, geologic time, biological evolution, and human origins. Of particular interest in geochemistry are geochemical cycles, such as the carbon cycle, in which carbon in various chemical forms is cycled between the atmosphere, the biosphere, the ocean, sediments, and the earth's deep interior and in doing so regulates Earth's climate. Continuous geochemical research is necessary to ensure future supplies of resources critical to modern society and mitigation of the effects of recovery, use, and disposal of those resources that are critical to human health and happiness.