Understanding the chemical processes that shape our planet and sustain life
Environmental geochemistry examines the chemical composition of Earth's systems and the natural processes that distribute elements between the atmosphere, hydrosphere, lithosphere, and biosphere . This field provides fundamental insights into how our planet functions and sustains life.
Over 99% of Earth's crust is composed of just 8 elements: oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium .
Many geochemical processes operate on timescales of thousands to millions of years, creating the stable environment necessary for life to evolve .
The study of natural geochemistry helps us understand the baseline conditions of our environment before human influence, providing crucial context for assessing anthropogenic impacts and developing sustainable practices .
Certain elements play disproportionately important roles in environmental processes due to their abundance, reactivity, or biological significance .
These elements constitute the bulk of Earth's crust and are fundamental to geological processes:
Percentage by weight in Earth's continental crust
Elements critical for life processes, often required in trace amounts:
These elements form the building blocks of biomolecules and enable metabolic processes
Elements move through Earth's systems in complex cycles that connect biological, geological, and chemical processes . These cycles regulate the availability of essential elements and maintain environmental stability.
Regulates climate and provides the fundamental building block for life .
Distributes heat and transports elements across the planet .
Converts atmospheric nitrogen into biologically usable forms .
The concentration of elements varies dramatically between different environmental compartments, reflecting their chemical properties and the processes that transport them .
| Element | Atmosphere | Freshwater | Ocean | Soil | Sediment |
|---|---|---|---|---|---|
| Oxygen | High | High | High | Medium | Low |
| Carbon | High | High | High | Medium | Low |
| Iron | Low | Medium | Low | Medium | High |
| Silicon | Low | Medium | Medium | High | High |
Mobility ratings indicate the relative ease with which elements move through each environmental compartment
Natural geochemical processes transform and redistribute elements, creating the dynamic equilibrium that characterizes Earth's environment .
The breakdown of rocks at Earth's surface through physical, chemical, and biological processes .
The reversible interchange of ions between solid and liquid phases, crucial for nutrient availability in soils .
This process regulates soil fertility and the availability of essential plant nutrients.
Formation of solid minerals from dissolved ions, creating sedimentary rocks and regulating ocean chemistry .
When solution becomes supersaturated, minerals precipitate out, forming deposits like limestone, salt flats, and evaporites.
Transfer of electrons between chemical species, driving many biogeochemical cycles .
These reactions control the speciation and mobility of elements like iron, manganese, and sulfur in natural systems.
Understanding natural geochemistry provides essential context for addressing environmental challenges and managing Earth's resources sustainably .
Human activities have significantly altered natural biogeochemical cycles, in some cases exceeding natural fluxes .
Natural processes remove CO₂ from the atmosphere through weathering, photosynthesis, and ocean uptake .
Geochemical processes naturally filter and purify water as it moves through soils and aquifers .
Natural systems can buffer against pollution through various geochemical mechanisms .