Biogeochemical Cycles

An ecosystem survives by a combination of energy flow and matter recycling

Biogeochemical cycles move all nutrients through air, water, soil, rock and living organisms

• Evaporation - water heating up and turning to gas

• Transpiration - water evaporation from the leaves of plants

• Condensation - water vapor cooling to form a cloud

• Precipitation - any moisture falling to Earth

• Driving force is the sun

• Water is the most important abiotic component of an ecosystem

• Water cycle is critical to other cycles

• Water is critical for photosynthesis

• Human cells are made of water

• Amount of water on earth is constant

• Using too much freshwater/groundwater reserves

• polluting water

• contributing to climate change

The circulation of carbon between the living organisms and the non-living components of ecosystems.

• Cellular Respiration - a process that makes energy (ATP) & involves a gas exchange

• Photosynthesis - the process of using sunlight to make glucose from CO₂ and water

• Combustion - process of burning fossil fuels (releases CO₂ & contributes to climate change)

The Primary function: to maintain a balance of carbon in nature

Carbon is an important component of proteins, lipids, DNA, and carbohydrates - the energy for living things!

Carbon dioxide helps to create a beneficial "greenhouse effect" to maintain Earth's temperature

• Humans alter the carbon cycle by adding excess CO₂ to the atmosphere by burning fossil fuels

• Clearing vegetation faster than it is replaced (less photosynthesis = more CO₂)

The nitrogen cycle is a proces through which nitrogen is converted to many forms, passing from the atmosphere to the soil to organisms and back to the atmosphere

• ~ 76% of the atmosphere is nitrogen gas, but it is not in a usable form

• Bacteria are the only organisms that can use nitrogen directly from the environment

• Some plants have a symbiotic relationship with bacteria that can help fix nitrogen for them & the plant provides carbohydrates for the bacteria

Nitrogen fixation - nitrogen gas in atmosphere to ammonia (bacteria in soil, lightning)

Nitrification - ammonia to nitrate (bacteria in soil)

Assimilation - absorption of ammonia and nitrate by plants

Ammonification - breakdown of dead organisms returns nitrogen to soil (bacteria and fungi) as ammonia

Denitrification - conversion of ammonia back to nitrogen gas (decomposers)

• Nitrogen is an essential component of amino acids and DNA

• Chlorophyll molecules - essential for photosynthesis - contain nitrogen

• Humans add nitrous oxide to the atmosphere from vehicles and factories which contributes to acid rain

• Excess addition of nitrogen through the use of fertilizers have negative impacts in ecosystems

Too much nitrogen in water causes algae blooms, which block sun in aquatic ecosystems, causing plants and animals to die