1. Biogeochemical Cycles
The biogeochemical cycle is the processes by which inorganic materials move from the atmosphere or soil into living organisms and back again.
Some materials reach ecosystems via the atmosphere (nitrogen, oxygen, water and carbon.)
Other elements are bound as minerals in rocks and soils.

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4. Water Cycle
Most chemical reactions and mineral transport within organisms cannot occur without water.
Water that sustains life on land is constantly cycled between the air and the earth.
Most of this cycling takes place through the processes of evaporation, transpiration, and precipitation.
The amount of water the atmosphere can hold depends on abiotic factors such as temperature and air pressure.
Great diagram & information:

5. Nitrogen
Plants and animals use nitrogen to build nucleic acids, structural proteins and enzymes.
Nitrogen makes up 78% of the atmosphere.
However, most living things cannot absorb nitrogen from the atmosphere.
They rely on nitrogen compounds found in the soils.
Nitrogen is converted by a process called the nitrogen cycle.

6. Nitrogen Cycle The nitrogen cycle has four major processes:
Nitrogen fixation: bacteria convert nitrogen gas into ammonia compounds
Ammonification: bacteria break down nitrogen containing amino acids from waste into ammonia
Nitrification: bacteria oxidize ammonia compounds to produce nitrites and nitrates
Denitrification: bacteria break down nitrates and release nitrogen gas back into the atmosphere
Diagram & description:

7. Carbon-Oxygen Cycle
During photosynthesis, plants use CO2 to make glucose and release oxygen.
Plants and animals use oxygen during respiration to produce energy and release CO2.
Photosynthesis and cellular respiration form the basis of the oxygen-carbon cycle.
The processes of photosynthesis and cellular respiration generally balance each other out.

9. Phosphorous Cycle
The element phosphorous is essential in molecules such as DNA and RNA.
Phosphorous is mainly found on land in rocks and minerals or dissolved in the ocean.
As the rocks and minerals erode, phosphate is released and absorbed by plants where it enters the food web.
Phosphorous moves through the ecosystem until it is deposited back into the soil or water through decomposition.

11. Nutrient Limitation
In any given ecosystem with abundant water and sunlight, the productivity of the ecosystem is limited by the available nutrients.
The limiting nutrient is the nutrient whose supply will limit overall productivity.

12. Limiting Nutrients in Ecosystems
In terrestrial, or soil-based ecosystems,, the limiting nutrient is usually nitrogen, phosphorous or potassium.
Other micronutrients in soil include: Ca, Mg, S, Fe or Mn.
In aquatic ecosystems, the limiting nutrient depends upon the type of water.
In oceans, nitrogen is often limited, but in freshwater, phosphorous is typically the limiting nutrient.

13. Human Impact on Cycles
On the Carbon-Oxygen cycle: