Biogeochemical Cycles Taylor Strickland

The Water Cycle

The water cycle has no real starting or ending point. As the water from the ocean is heated by the sun it evaporates into the atmosphere and changes into a vapor. When the water is evaporated from plants and the soil it is called evapotranspiration. Other sources such as snow and ice sublimate from their solid state to a gas. As the vapors cool they condense into clouds. The clouds travel around the world by air currents and eventually the clouds collide causing precipitation. Some of the precipitation falls as snow or ice but most falls as rain and accumulates back into rivers and oceans. All of the water either is infiltrated into the ground, by plants or is apart of the surface run off.

chemical reactions

The chemical reaction that occurs in the water cycle is between hydrogen and oxygen to form water.



Inorganic Elements within the Water Cycle

  1. Sulfate
  2. Iron
  3. Chloride
  4. Manganese
  5. Fluoride

Organic Elements within the Water Cycle

  1. Carbon
  2. Roots of decomposed vegetation
  3. Decomposed aquatic plants and animals
  4. Microorganisms
  5. Residues of organic matter

Impact of Humans on the water cycle

Humans impact the water cycle in a very crucial way. When we litter and pollute the environment we are polluting the water cycle. Without clean water the polluted water will cycle around the earth again and again.

The Carbon Cycle

The Carbon Cycle

Carbon is found in many places on earth, such as fossil fuels and within the atmosphere. The carbon cycles through the atmosphere, animals, ocean and the land. Carbon is not created through the cycle, the earth has a set amount that continuously travels around the earth and through the atmosphere. The Carbon cycle begins with respiration/breathing or combustion/burning, which is then released into the atmosphere as carbon dioxide. Next, carbon dioxide is absorbed by producers/plants. The plants are then eaten by animals who die and release carbon back into the atmosphere and the rest of the animals remains are consumed by decomposers in the ground.

Chemical Reactions Involved

C6H12O6 (organic matter) + 6O2 ⇒ 6CO2 + 6H2O + energy (Respiration)

Energy (sunlight) + 6CO2 + H2O ⇒ C6H12O6 + 6O2 (Photosynthesis)

Organic components

  • Plants and animals
  • Fossil Fuels

Inorganic Compounds

  • Limestone
  • Carbon reservoirs

How Humans Affect the Carbon Cycle

Humans disrupt the natural carbon cycle by doing very simple things. Humans inevitably interrupt the cycle just by exhaling, but other things like burning fossil fuels, deforestation and agricultural malpractice.

The Nitrogen Cycle

The Nitrogen cycle

The Nitrogen Cycle consists of 3 parts: Nitrogen Fixation, Nitrification, and Denitrification. Nitrogen fixation is a process in which symbiotic bacteria break down nitrogen into ammonia in the soil so plants can absorb it because they can't get it from the atmosphere. Nitrification is the process that involves fixed nitrogen, bacteria called nitrosomonas break down that fixed nitrogen into nitrate. Lastly, the process of denitrification is when fungi and other organisms break down the nitrogen in the soil and release it into the atmosphere after converting it.

Chemical Reactions Involved

N2 + 3 H2 -> 2 NH3 : Nitrogen Fixation

2 NH3 + 3O2 - > 2 NO2 + 2 H+ + 2 H2O 2 NO2- + O2 -> 2 NO3- : Nitrification

NO3- + CH2O + H+ -> ½ N2O + CO2 + 1½ H2O : Denitrification

Inorganic Components in the Nitrogen Cycle
  • Amonia
  • Nitrogen
  • Nitrite
  • Nitrate
  • Urea
Effect Humans have on the Nitrogen Cycle

Humans disrupt the nitrogen cycle by burning fossil fuels, and using nitrogen based fertilizers . This causes a change in carbon storage and the available nitrogen in the atmosphere. Nitrogen is a essential element to all living organisms, so this could potentially be very dangerous.

Phosphorus Cycle

The Phosphorus Cycle

The phosphorous cycle, goes through plants, animals, water, sediments, and rocks. Weathering of rocks causes them to release minerals, such as phosphorus, into the soil and water. Once in the water and soil it is absorbed by plants, which are then consumed by animals. Once the plant or animal dies it releases the element back into the soil after decaying. The phosphate is returned to the plants by bacteria, through a process called mineralisation, that breaks down organic matter into inorganic forms of phosphorus. The elements make their way into ground water and the oceans which are then infused with the sediment.

Chemical Reactions Involved

P4 (s)+502 (g) P4010(s) : Phosphorus reacting with air

Inorganic components in the Phosphorus Cycle

  • Organic deposits can be found in Peru, where excretions of birds have accumulated and washed away into the cycle.
  • Inorganic deposits of phosphorus occur in the mineral apatite.
Human impact on the Phosphorus Cycle

One huge way that humans impact the phosphorus cycle is that in farming, the plants are taken away from the soil when they die. The plants are not given a chance to decompose and decay back to their elements in the soil. This causes the soil to run out of phosphorus deposits very quickly.


Created with images by clondike7 - "Water" • cocoparisienne - "forest fog hirsch" • strikers - "landscape reflection water" • Nhelia - "lupinien nature new zealand"

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