1. Biogeochemical Cycles
The cycling of nutrients within ecosystems
Energy Flow in Ecosystems
April 24, 2017

2. Biogeochemical Cycles
Life on Earth depends on recycling essential chemical elements.
Biogeochemical cycles move elements between the atmosphere, hydrosphere, lithosphere, and biosphere.
Carbon is a necessary building block for most biomolecules
Phosphorus is necessary for DNA, RNA and the energy molecule ATP
Nitrogen is a key component in proteins, DNA, RNA and many enzymes
Water is necessary for most chemical functions
Energy Flow in Ecosystems
April 24, 2017

3. General Nutrient cycle model
Nutrients cycle between abiotic and biotic components of the ecosystem
Energy Flow in Ecosystems
April 24, 2017

4. 1. The water cycle Water is essential to all living things
Typically found in oceans, lakes, rivers, ice caps, groundwater (small amount in atmosphere)
Cycles via sublimation, precipitation, evaporation, condensation, consumption, transpiration
Energy Flow in Ecosystems
April 24, 2017

5. The Water cycle
Water is necessary for most chemical processes in living organisms.
The water cycle includes both biotic and abiotic processes.
Water in oceans, rivers etc. evaporates into the atmosphere.
Energy Flow in Ecosystems
April 24, 2017

6. Clouds form when water vapour condenses and water falls back to the ground in the form of precipitation.
Water returns to the ocean etc. through runoff or returns to aquifers through seepage.
Plants take up water and return unused water to the atmosphere through transpiration.
Animals take up water and return it through perspiration, breathing, and elimination

7. The Water cycle Net movement of water vapor by wind (36) Solar heat
Water vapor over the land
Water vapour over the sea
Precipitation over the land (95)
Evaporation and transpiration (59)
Precipitation over the sea (283)
Evaporation from the sea (319)
Surface
water and groundwater
Flow of water from land to sea (36)
Oceans
Energy Flow in Ecosystems
April 24, 2017

8. 2. The Carbon cycle Carbon is essential to building organic molecules
Can be found in the atmosphere (CO2), plants, animals, fossil fuels, soils, sediments
Cycles via photosynthesis, respiration, combustion, consumption
Energy Flow in Ecosystems
April 24, 2017

9. The Carbon Cycle CO 2 in the atmosphere diffuses into the water.
Both land and aquatic plants take in CO 2 and produce carbohydrates and other biomolecules through photosynthesis.

10. 2. Carbon Cycle
Producers: Plants take in CO2 and make sugar by photosynthesis.
Consumers: Animals eat plants to get energy (respiration) from sugar and make proteins from the carbon.
Breath out CO2 as a waste product of respiration.
Animals die and dentritus (decomposers) break down the carbon and other elements back into the soil and air for plants to use again.
Human activities such as burning fossil fuels, and cutting and burning forests puts carbon back into the atmosphere.
Energy Flow in Ecosystems
April 24, 2017

11. Higher-level consumers
The Carbon cycle
CO2 in atmosphere
Burning
Wood and fossil fuels
Cellular respiration
Higher-level consumers
Decomposition
Detritivores
Photosynthesis
Producers
Primary consumers
Detritus
Energy Flow in Ecosystems
April 24, 2017

12. 3.The Nitrogen cycle
Found in the atmosphere (it is 80% N2), soils, sediments, water, organisms
Nitrogen is part of important biological molecules and limits plant growth
Nitrogen in nitrate forms are used by plants for production of amino acids and nucleic acids for protein synthesis and DNA
Animals get amino acids by eating plants or animals that have eaten plants.
N2 in the atmosphere is FIXED into ammonia (NH3) by nitrogen fixing bacteria in the soil.
a small amount is fixed during chemical reaction that occur during lightening storms.
Energy Flow in Ecosystems
April 24, 2017

13. Nitrogen Fixation by bacteria
Plants need nitrogen but cannot take it in from the air.
Bacteria in the soil on the roots of plants take in nitrogen (N2) and make ammonia (NH4) which plants can then use to get nitrogen.
Ammonification is the breakdown of nitrogen products in waste and decomposing tissue to return it to the cycle.
Denitrification is the conversion of ammonia in the soil to free nitrogen by denitrifying bacteria.
Energy Flow in Ecosystems
April 24, 2017

15. Nitrogen (N2) in atmosphere
The Nitrogen cycle
Denitrifying bacteria
Assimilation by plants
Nitrogen (N2) in atmosphere
Amino acids and proteins in plants and animals
Detritus
Detritivores
Nitrogen-fixing bacteria in root nodules of legumes
Decomposition
Nitrogen fixation
Nitrogen-fixing bacteria
in soil
Ammonium (NH4+ )
Nitrifying bacteria
Nitrates (NO3– )
Energy Flow in Ecosystems
April 24, 2017

16. 5. The Phosphorous cycle
Important component of many biological molecules (nucleic acids, ATP)
Found in rocks in great amount, some in soils and water
Cycles through weathering, taken up by organisms, sedimentation
Energy Flow in Ecosystems
April 24, 2017

17. The Phosphorus Cycle
Phosphorus in the rocks leaches into the soil where it is taken up by plants.
Producers make nucleic acids and when they are eaten pass the phosphorus through the food chain to consumers.
Phosphorus reenters the soil through decomposition and waste.

18. Precipitated (solid) phosphates Phosphates in solution
The Phosphorous cycle
Uplifting of rock
Phosphates in rock
Weathering of rock
Phosphates
in organic compounds
Consumers
Producers
Detritus
Rock
Phosphates
in soil (inorganic)
Precipitated (solid) phosphates
Phosphates in solution
Detritivores in soil
Energy Flow in Ecosystems
April 24, 2017