Biogeochemistry

Key Takeaways

Biogeochemistry studies how crucial elements such as carbon and nitrogen cycle and interact as they move through Earth’s atmosphere, hydrosphere, biosphere, and lithosphere.
The carbon cycle is a prime example: photosynthesis, decomposition, burial in seafloor sediments, and volcanic release move carbon through the whole Earth system over millions of years.
Understanding these interlinked cycles helps WHOI scientists explain how life is sustained and how the ocean helps regulate climate.

Biogeochemistry follows the planet’s essential elements — carbon, nitrogen, sulfur, phosphorus — as they cycle through the atmosphere, ocean, living things, and rock. If chemicals are a kind of planetary currency, biogeochemistry is the study of the transactions that sustain life and regulate Earth’s climate.

What is Biogeochemistry?

Biogeochemistry is a relatively new scientific discipline that explores the physical, chemical, biological, and geological processes and reactions that govern the composition of and changes to the natural environment. In particular, biogeochemistry studies the cycles of crucial elements, such as carbon and nitrogen, and their interactions with other substances and organisms as they move through Earth’s atmosphere, hydrosphere (water and ice), biosphere (life), and lithosphere (rock). The field focuses especially on the diverse and interlinked chemical cycles that are either driven by or have an impact on biological activity, in particular carbon, nitrogen, sulfur, and phosphorus.

A prime example is carbon, the building block of life on Earth, and the planet-encompassing carbon cycle. Photosynthetic plants on land and sea take carbon dioxide (a form of inorganic carbon) from the atmosphere and convert it into the organic forms of carbon they need to live and grow. Animals that consume the plants incorporate the organic carbon into their own bodies.

Microbes eventually decompose dead plants and animals, and their carbon is recycled into soils and groundwater or swept into the oceans, where it becomes available to microbes and phytoplankton at the base of the marine food chain or it sinks and is buried in seafloor sediments. Over millions of years, carbon that is buried on land or at the bottom of the ocean becomes incorporated into rocks or hydrocarbons, where it might remain for tens to hundreds of millions of years. Ultimately, volcanoes return some of this carbon to the air as gas, where its heat-trapping properties affect Earth’s climate, or else the rocks containing carbon are uplifted onto continents and gradually weathered, releasing their carbon back to the environment and making it available to organisms once again.

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The Biological Pump

The biological pump converts greenhouse gas that warms Earth climate into organic carbon that is then stored in the depths of the ocean.

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Two Chemical Roads Diverge in an Open Ocean illustration

An exploration of how and why manganese oxide deposits form in the environment

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Nitrogen cycle, with imbedded callouts, captions

Chemical detectives follow nitrogen's elusive and essential trail in the ocean.

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Mercury cycle illustration

Mercury cycles between Earth, air, and ocean, where it becomes toxic monomethylmercury that builds up in tuna, swordfish, and other fish we consume.

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The carbon exchange cycle

Carbon moves between air, land, and sea. In the ocean, CO2 dissolves, is used by life, or stored in deep rocks—key to climate and life on Earth.

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How the Dimethylsulfoniopropionate (DMSP) compound affects the environment

DMSP is synthesized by phytoplankton—the microscopic marine plants at the heart of the ocean food web—for a variety of beneficial uses.

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How a hydrothermal vent system works

Hydrothermal vents form in places where there is volcanic activity, such as along the Mid-Ocean Ridge.

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How the Fraser River picks up chemical signatures along its journey

Samples from the Fraser River help scientists track a geochemical journey that starts in the atmosphere, moves through rocks and plants, and sinks to the seafloor.

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Diatoms and Coccoliths carbon-dioxide carbon removal from atmosphere

Conditions that influence how diatoms and coccoliths removal of carbon-dioxide — from the atmosphere to the deep ocean.

Why is it Important?

In a sense, chemicals are like currency, and biogeochemistry is the study of the nearly limitless “transactions” that drive the entire planetary system, including life on Earth. Understanding these fundamental processes provides crucial insights into how life formed, has evolved, is sustained, and is threatened on our planet, and how the various chemical cycles govern and regulate Earth’s climate and environment.

Such knowledge enhances our ability to find ways to adapt to climate change and its impacts, enhance agriculture and food production, manage fisheries, mitigate pollution, develop alternative and renewable energy, prevent diseases and create new drugs, and spur innovations that can drive economic prosperity and improve our quality of life.

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