Biogeochemistry - (n.)

Life on our planet is made up of an incredible variety of carbon molecules - in essence, life processes can simply be viewed as carbon chemistry. Conversely, the carbon cycle, the movement of carbon atoms through the various reservoirs in the climate-driven part of Earth, is intimately tied to life processes. In the study of the carbon cycle, biology and geochemistry merge to form a new scientific discipline, called "biogeochemistry." Biogeochemists study the carbon cycle in its interconnections with the cycles of other elements involved in life processes, mainly nitrogen, oxygen and phosphorus, but also sulfur and iron and certain trace metals. Also, the water cycle helps drive the carbon cycle, and this is where climate and the carbon cycle are most intimately connected.

Biogeochemistry includes the history of the great carbon reservoirs in the crust of the Earth, the limestones and the coal deposits, as well as the distribution of nitrate and phosphate in the ocean. It seeks to explain the composition of the atmosphere, consisting of nitrogen, oxygen and the trace gases, as a result of bacterial action and photosynthesis. And it records the exchange of matter at the interfaces such as the decay of organic matter in soils and the resulting gases released into the air, the uptake of oxygen by the ocean and its utilization at depth, and the leaching of nutrients from the soil and their transport into the sea. In a sense, biogeochemistry treats the dynamic systems near the surface of Earth as a few interacting organisms living in symbiosis, where the waste products of one become the stuff of life for the other. For example, the ocean takes up oxygen (the waste product of plants) and releases an equivalent amount of carbon dioxide (the waste product of decay and the stuff of growth for plants). The all-important role of life processes in maintaining Earth's environments was stressed early in the 20th century by the Russian chemist Vladimir Vernadsky (1863-1945), who may be considered the father of biogeochemistry, although that term had not been invented at the time. The American limnologist and geochemist G. Evelyn Hutchinson (1903-1991) first outlined the broad scope and principles of the new field and led the way. More recently, the basic elements of the discipline of biogeochemistry have been restated and popularized by the British engineer and science writer James Lovelock (born 1919) under the label of the "Gaia Hypothesis." Lovelock emphasizes a concept that life processes regulate the radiation balance of Earth to keep it habitable.