Biogeochemical Cycles

• One of the serious consequences of disrupting a natural cycle is the threat of global warming.
• Processes involved in the hydrologic cycle, the most important are: • evaporation • transpiration • condensation • precipitation • runoff
• Evaporation - is the change of state in a substance from a liquid to a gas.
• Transpiration - is the evaporation of water from plants through stomata.
• Condensation - is the process whereby water vapor is changed into a liquid state.
• Precipitation - is when tiny condensation particles, through collision and coalescence, grow too large for the rising air to support, and thus fall to the Earth.
• Precipitation can be in the form of rain, hail, snow, or sleet.
• Runoff - is when there is excessive precipitation and the ground is saturated.
• Humans disrupt the water cycle by over pumping aquifers faster than they are replenished and by polluting the aquatic environments.
• Biogeochemical Cycles consists of:

  • Hydrologic

  • Carbon

  • Oxygen

  • Nitrogen

  • Phosphorus
• Carbon Cycle - is the process by which carbon from the atmosphere is constantly cycled around the ecosystem.
• Carbon is removed from carbon dioxide in the air by plants during photosynthesis to make carbohydrates, their vital source of food and energy.
• Humans disrupt the Carbon Cycle by adding more Carbon Dioxide into the atmosphere through the combustion or burning of fossil fuels.
• Climate change also exacerbates carbon dioxide emission into the atmosphere by releasing the carbon dioxide trapped in oceans.
• Oxygen cycle - refers to the movement of oxygen through the atmosphere , biosphere and the lithosphere.
• Respiration - the movement of oxygen from the outside environment to the cells within tissues.
• Combustion - a chemical process in which a substance reacts rapidly with oxygen and gives off heat.
• Rusting - is the interaction of Iron with air and water produces rust.
• Photosynthesis - is the process by which green plants and certain other organisms transform light energy into chemical energy.
• Clearing photosynthesizing vegetation faster than it is replaced can increase the amount of carbon dioxide an d reduce oxygen content in the air, making earth warmer than it should.
• Nitrogen Cycle - is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere.
• Humans intervene with the nitrogen cycle by adding large amounts of nitric oxide into the atmosphere when humans burn fossil fuels at high temperature.
• Humans also add nitrous oxide through commercial inorganic fertilizers applied to soil.
• The phosphorus cycle - a biogeochemical cycle that involves the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.