THE CYCLING OF NUTRIENTS WITHIN ECOSYSTEMS

Biogeochemical Cycles

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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 biomoleculesPhosphorus is necessary for DNA, RNA and the energy molecule

ATPNitrogen is a key component in proteins, DNA, RNA and many

enzymesWater is necessary for most chemical functions

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Energy Flow in Ecosystems

Biogeochemical Cycles

Nutrients cycle between abiotic and biotic components of the ecosystem

General Nutrient cycle model

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Energy Flow in Ecosystems

1. The water cycleWater is essential to all

living thingsTypically found in

oceans, lakes, rivers, ice caps, groundwater (small amount in atmosphere)

Cycles via sublimation, precipitation, evaporation, condensation, consumption, transpiration

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Energy Flow in Ecosystems

The Water cycle

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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.

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

The Water cycle

Precipitation over the sea (283)

Solar heat

Water vapour over the sea

Oceans

Net movement of water vapor by wind (36)

Evaporation from the sea (319)

Evaporation and transpiration (59)

Water vapor over the

land

Precipitation over the land (95)

Surfacewater and

groundwater

Flow of water from land to sea (36)

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Energy Flow in Ecosystems

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

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Energy Flow in Ecosystems

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.

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.

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Energy Flow in Ecosystems

CO2 in atmosphere

Burning

Wood and fossil fuels

Cellular respiration

Higher-level consumers

Decomposition

Detritivores

Photosynthesis

Producers

Primary consumers

Detritus

The Carbon cycle

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Energy Flow in Ecosystems

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.

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Energy Flow in Ecosystems

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.

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Energy Flow in Ecosystems

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 legumesDecomposition

Nitrogen fixation Nitrogen-

fixing bacteriain soil

Ammonium (NH4

+ )Nitrifying bacteria

Nitrates (NO3

– )

The Nitrogen cycle

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Energy Flow in Ecosystems

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

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Energy Flow in Ecosystems

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.

The Phosphorous cycle

Uplifting of rock

Phosphates in rock

Weathering of rock

Phosphatesin organic

compoundsConsumers

Producers

Rock

Precipitated (solid)

phosphatesPhosphates in solution

Phosphatesin soil

(inorganic)

Detritus

Detritivores in soil

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Energy Flow in Ecosystems