# Biogeochemistry

Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the cryosphere, the hydrosphere, the pedosphere, the atmosphere, and the lithosphere). In particular, biogeochemistry is the study of biogeochemical cycles, the cycles of chemical elements such as carbon and nitrogen, and their interactions with and incorporation into living things transported through earth scale biological systems in space and time. The field focuses on chemical cycles which are either driven by or influence biological activity. Particular emphasis is placed on the study of carbon, nitrogen, oxygen, sulfur, iron, and phosphorus cycles. Biogeochemistry is a systems science closely related to systems ecology.

## History
### Early Greek

Early Greeks established the core idea of biogeochemistry that nature consists of cycles.

### 18th-19th centuries

Agricultural interest in 18th-century soil chemistry led to better understanding of nutrients and their connection to biochemical processes. This relationship between the cycles of organic life and their chemical products was further expanded upon by Dumas and Boussingault in a 1844 paper that is considered an important milestone in the development of biogeochemistry. Jean-Baptiste Lamarck first used the term biosphere in 1802, and others continued to develop the concept throughout the 19th century. Early climate research by scientists like Charles Lyell, John Tyndall, and Joseph Fourier began to link glaciation, weathering, and climate.

### 20th century

The founder of modern biogeochemistry was Vladimir Vernadsky, a Russian and Ukrainian scientist whose 1926 book The Biosphere, in the tradition of Mendeleev, formulated a physics of the Earth as a living whole. Vernadsky distinguished three spheres, where a sphere was a concept similar to the concept of a phase-space. He observed that each sphere had its own laws of evolution, and that the higher spheres modified and dominated the lower:
* Abiotic sphere – all the non-living energy and material processes
* Biosphere – the life processes that live within the abiotic sphere
* Nöesis or noosphere – the sphere of human cognitive process
Human activities (e.g., agriculture and industry) modify the biosphere and abiotic sphere. In the contemporary environment, the amount of influence humans have on the other two spheres is comparable to a geological force (see Anthropocene).
The American limnologist and geochemist G. Evelyn Hutchinson is credited with outlining the broad scope and principles of this new field. More recently, the basic elements of the discipline of biogeochemistry were restated and popularized by the British scientist and writer, James Lovelock, under the label of the Gaia Hypothesis. Lovelock emphasized a concept that life processes regulate the Earth through feedback mechanisms to keep it habitable. The research of Manfred Schidlowski was concerned with the biochemistry of the Early Earth.

## Biogeochemical cycles

Biogeochemical cycles are the pathways by which chemical substances cycle (are turned over or moved through) the biotic and the abiotic compartments of Earth. The biotic compartment is the biosphere and the abiotic compartments are the atmosphere, hydrosphere and lithosphere. There are biogeochemical cycles for chemical elements, such as for calcium, carbon, hydrogen, mercury, nitrogen, oxygen, phosphorus, selenium, iron and sulfur, as well as molecular cycles, such as for water and silica. There are also macroscopic cycles, such as the rock cycle, and human-induced cycles for synthetic compounds such as polychlorinated biphenyls (PCBs). In some cycles there are reservoirs where a substance can remain or be sequestered for a long period of time.

## Research

Biogeochemistry research groups exist in many universities around the world. Since this is a highly interdisciplinary field, these are situated within a wide range of host disciplines including: atmospheric sciences, biology, ecology, geomicrobiology, environmental chemistry, geology, oceanography and soil science. These are often bracketed into larger disciplines such as earth science and environmental science.
Many researchers investigate the biogeochemical cycles of chemical elements such as carbon, oxygen, nitrogen, phosphorus and sulfur, as well as their stable isotopes. The cycles of trace elements, such as the trace metals and the radionuclides, are also studied. This research has obvious applications in the exploration of ore deposits and oil, and in the remediation of environmental pollution.
Some important research fields for biogeochemistry include:
* modelling of natural systems
* soil and water acidification recovery processes
* eutrophication of surface waters
* carbon sequestration
* environmental remediation
* global change
* climate change
* biogeochemical prospecting for ore deposits
* soil chemistry
* chemical oceanography

## Evolutionary Biogeochemistry

Evolutionary biogeochemistry is a branch of modern biogeochemistry that applies the study of biogeochemical cycles to the geologic history of the Earth. This field investigates the origin of biogeochemical cycles and how they have changed throughout the planet's history, specifically in relation to the evolution of life.