Aim: to explore the carbon and nitrogen cycles Objectives Describe how energy flows in an ecosystem Illustrate the carbon and nitrogen cycles Explain how human activity is affecting carbon emissions
Trophic Levels Energy moves from one organisms to another when it is eaten Each step in this transfer of energy is known as a trophic level The main trophic levels are producers and consumers
Food Chains The energy flow from one trophic level to the other is know as a food chain A simple food chain shows how energy is transferred from the sun through living organisms. It involves one organism at each trophic level Producers (e.g. plants) Primary Consumers Secondary Consumers Tertiary Consumers
Atmospheric Carbon DioxidePlants use carbondioxide to make theirfood (photosynthesis)
Atmospheric Carbon DioxidePlants use carbondioxide to make theirfood (photosynthesis) Green plants are eaten by animals
Atmospheric Carbon Dioxide respirationPlants use carbondioxide to make theirfood (photosynthesis) Green plants are eaten by animals
Atmospheric Carbon Dioxide respirationPlants use carbondioxide to make theirfood (photosynthesis) green plants are eaten by animals dead remains of plants and animals
Atmospheric Carbon Dioxide respirationPlants use carbondioxide to make theirfood (photosynthesis green plants are eaten by animals dead remains of plants and animals decay by fungi and bacteria
Plants use carbon Carbon is pulled from the atmosphere by plants and used for the process of photosynthesis used to make organic molecules (carbohydrate, proteins and fats)• The carbon becomes part of the plant (stored food).
Animals eat plants When organisms eat plants, they digest the organic compounds and use these products for their own purposes. All leaving organisms carry out respiration breaking down food substances to release energy. This also produces carbon dioxide which returns to the atmosphere.
When plants and animals die, most of their bodies are decomposed by fungi and bacteria. They break down organic compounds via respiration to carbon dioxide and carbon atoms are returned to the atmosphere. Some are not decomposed fully and end up in deposits underground (oil, coal, etc.). Humans burn these fuels releasing carbon dioxide into the atmosphere.
Carbon Cycle Diagram Carbon in Atmosphere Decomposers break down dead Plants use carbon things, releasing to make food carbon to atmosphere and Plants and soil animals die Fossil fuels are Animals eat burned; carbon plants and take is returned to Bodies not in carbon atmosphere decomposed — Carbon slowly after manyreleased from these years, become part substances returns of oil or coal to atmosphere deposits
Carbon in Oceans Additional carbon is stored in the ocean. Many animals pull carbon from water to use in shells, etc. Animals die and carbon substances are deposited at the bottom of the ocean. Oceans contain earth’s largest store of carbon.
Human Impact Fossil fuels release carbon stores very slowly Burning anything releases more carbon into atmosphere — especially fossil fuels Increased carbon dioxide in atmosphere increases global warming Fewer plants mean less CO2 removed from atmosphere
Greenhouse Gases The greenhouse effect is causing the Earth to warm up. This is causing climate change and melting of the polar ice caps, this It is due to increasing could lead to flooding. amounts of greenhouse gases, such as carbon Burning fuels is a dioxide, water vapour and major cause of this methane. increase. Video
Nitrogen (N2) in atmosphere Amino acids Assimilation and proteins in plants and animals Nitrogen by plants fixationDenitrifying bacteria Detritus Nitrogen-fixing bacteria in root Nitrates nodules of legumes (NO3–) Detritivores Nitrogen-fixing Decomposition bacteria in soil Nitrogen fixation Ammonium (NH4+)
The largest single source of nitrogen is in the atmosphere. Nitrogen (N2) makes up 79% of our air! But living organisms cannot use this form directly
There are 4 phases in the cycle: Nitrogen fixation = NH3/NH4+ Decay = decomposing organic nitrogen into NH4+ Nitrification = converting NH4+ to NO2 to NO3 Denitrification = converting NO3 into N2 Micro-organisms play an important part in this cycle!
Nitrogen Fixation• The enormous energy of lightning breaks nitrogen molecules apart and enables the nitrogen atoms to combine with oxygen forming nitrogen oxides (N2O)• Nitrogen oxides dissolve in rain, forming nitrates (NO3)• Nitrates (NO3) are carried to the ground with the rain. N N O (N2O) (NO3)
Lightning “fixes” Nitrogen! N N O Nitrogen combines with Oxygen Nitrogen oxides forms(N2O) Nitrogen oxides dissolve in rain and(NO3) change to nitrates Plants use nitrates to grow!
Industrial Fixation NN H Under great pressure, at a N H3 temperature of 600 Industrial Plant combines ºC, and with the use of a nitrogen and hydrogen catalyst, atmospheric nitrogen (N2) and hydrogen are combined Ammonia is formed to form ammonia (NH3). (NH3) Ammonia can be used as a fertiliser. Ammonia is used as a fertilizer in soil
Biological Fixation Some bacteria, including Rhizobium, live in the soil or within root nodules of legumes (peas, beans and clover) These bacteria are anaerobic and use enzymes to convert nitrogen gas (N2) to ammonium ions (NH4+) The plants supply the bacteria with energy and nutrients in return of nitrogen fixation (mutualism)
Symbiotic Relationship Legume plantsBacteriaBacteria live in the roots of Nlegume family plants andprovide the plants withammonium (NH4) in exchange NH3for the plant’s carbon and aprotected home. N Roots with nodules where bacteria live Nitrogen changes into ammonium
Decay Animals acquire their amino acids when they eat plants. When animals and plants die their remains are used as food by micro-organisms such as bacteria and fungi. Decomposers convert the nitrogen back into ammonia (NH3)Decomposers convert organic nitrogento ammonia (NH3) Ammonia (NH3) is used by some plants Ammonia (NH3) is stored in soil.
Nitrification• Living in the soil are nitrifying bacteria.• First, Nitrosomonas bacteria combine ammonia with oxygen to form nitrites.• Then another group of nitrifying bacteria, Nitrobacter, convert nitrites to nitrates which green plants can absorb and use! Nitrifying bacteria in soil combine ammonia with oxygen Ammonia changes to nitrites Nitrifying bacteria in soil convert Nitrates nitrites to nitratesAmmonia Nitrites (NH3) (NO2) (NO3) Plants absorb nitrates and grow!
Denitrification Denitrification converts nitrates (NO3) in the soil to atmospheric nitrogen (N2) which is returned to the air. Denitrifying bacteria live deep in soil and in aquatic sediments where conditions make it difficult for them to get oxygenDenitrifying bacteria live (NO3) (N2)deep in soil and usenitrates as an alternative Nitrogen into oxygen making a atmosphere closes thebyproduct of nitrogen gas. nitrogen cycle!
Acid RainHuman activity have doubledthe amount of fixed nitrogenentering the nitrogen cycle injust 100 years Manufacture and use of nitrogen fertilisers, combustion of Climate change, acid fossil fuels and forest rain, the acidification of burning soils and loss of soil nutrients, and the acidification of streams and lakes. Kills fish, damages trees and buildings. Video