Biogeochemical Cycles and Water Cycle

Study Notes

Refer to the interconnected chemical cycles within the biological and geological world.
Each chemical has a unique cycle, but all share common components: Reservoirs and Exchange Pools.
Reservoirs: Hold large quantities of a chemical for long periods (e.g., oceans, lakes).
Exchange Pools: Hold chemicals for short periods (e.g., clouds, lungs).

Describes the movement of water through its different states (vapor, liquid, solid) across the ocean, atmosphere, groundwater, streams, etc.
Powered by the sun's energy that drives evaporation.

Evaporation: Liquid water transforms into gaseous water vapor, requiring significant heat.
Transpiration: Biological process where plants release water vapor into the atmosphere through their leaves.
Condensation: Water vapor changes from a gaseous state to a liquid, forming dew, fog, or clouds.
Precipitation: Condensed water vapor falls back to Earth as rain, snow, sleet, or hail.

Involves the movement of carbon in various forms between the biosphere, atmosphere, oceans, and geosphere.

Respiration: Organisms use carbohydrates and oxygen to produce carbon dioxide, water, and energy (O2 + Carbohydrates = CO2 + H2O + energy).
Photosynthesis: Plants use carbon dioxide and water to produce oxygen and carbohydrates.

Involves the conversion of nitrogen gas into nitrogen compounds through the atmosphere, soil, and organisms.

Nitrogen Fixation (Atmosphere): Lightning converts nitrogen gas into nitrates.
Nitrogen Fixation (Soil): Rhizobium bacteria in legumes convert atmospheric nitrogen (N2) into ammonia, which plants can utilize.
Nitrification: Nitrifying bacteria convert ammonia into nitrates.
Assimilation: Plants and animals absorb nitrates and ammonia to build their tissues.
Ammonification: Decomposers convert ammonia from dead animals and waste products into ammonia.
Denitrification: Bacteria convert nitrates into gaseous nitrogen, returning it to the atmosphere.

The simplest biogeochemical cycle, describing phosphorus transformation and movement in soil, water, and living/dead organic material.
Phosphorus exists primarily as phosphate.

Weathering: Phosphorus in rocks weathers, releasing phosphate salts into the soil.
Absorption by Plants: Plants absorb dissolved phosphate salts from the soil.
Absorption by Animals: Animals obtain phosphorus by eating plants or other animals.
Return to Ecosystem: Decomposers break down dead organisms, converting organic phosphorus back to inorganic forms, which are recycled to soil and water.
Phosphorus eventually ends up in sediments and rocks, where it can be released again through weathering.