The Biosphere and Biogeochemical Cycles

Transcription

1 The Biosphere and Biogeochemical Cycles

2 The Earth consists of 4 overlapping layers: Lithosphere Hydrosphere (and cryosphere) Atmosphere Biosphere

3 The Biosphere The biosphere is the layer of life around the earth it consists of all the living organisms and their habitats The biosphere overlaps the other layers of the earth.

4 Biogeochemical Cycles The chemical elements that are essential to life are constantly circulating within the biosphere, they are constantly being recycled in loops these loops are called biogeochemical cycles A biogeochemical cycle refers specifically to the steps necessary for an element to pass from one environment to the next and then eventually return to its original environment

5 The Carbon Cycle All life is based on the element carbon. Carbon is the major chemical element in complex molecules of organic matter (proteins, fats and carbohydrates) these molecules make up the tissues of living organisms Carbon is also a part of the ocean, air, and even rocks Carbon is also part of CO2 and CH4(methane) gases which make up part of our atmosphere as well as a major component of fossil fuels

6 Carbon is constantly being exchanged between living organisms, dead organisms, the atmosphere, oceans, rocks and soil in the Carbon Cycle Human activities have upset the balance of the carbon cycle the burning of fossil fuels and decomposition of human waste has resulted in large amounts of CO2 and CH4 being transferred to the atmosphere

7 What processes move carbon through the biosphere?

8 Addition of Carbon into the Environment (from the atmosphere): 1. Photosynthesis plants use CO2 to convert it to glucose as a source of energy 2. Ocean Uptake a) Dissolving of CO2 into the water (oceans, lakes, rivers etc) b) Photosynthetic plants/organisms absorb CO2

9 Movement of Carbon through the environment: 1. Consuming: animals eat plants or other animals to get the carbon they need 2. Dead Organisms and waste a) Animals and plants become fossil fuels 3. Ocean Uptake a) Photosynthetic plants/organisms absorb CO2 b) Formation of Shells and skeletons c) Carbonate rock (limestone)

10 Removal of Carbon from the environment (into the atmosphere): Respiration Decomposition of waste: waste (urine, feces, dead organisms etc) are broken down by decomposers which release CO2 and CH4 Forest Fires Volcanic Eruptions Combustion of Fossils Fuels

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13 Carbon Cycle Video (2:20-4:00)

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15 The Nitrogen Cycle The nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids (found in DNA and proteins) While nitrogen gas (N2) is the most abundant gas in the atmosphere, most organisms cannot use it, they need bacteria to change it into ammonia (NH3), ammonium (NH4+), nitrites (NO2-) or nitrates (NO3-)

16 Many factors can affect the nitrogen cycle: Temperature Relative humidity ph Human activity: fertilizers in the soil and discharges from factories Nitrogen surpluses change the soil balance and interfere (in the long term) with plant growth and can cause eutrophication in lakes

17 What processes move Nitrogen through the biosphere?

18 1. Nitrogen Fixation: 1 denitrification Bacteria take N2 from the atmosphere and convert it to ammonia (this can then be converted to ammonium)

19 2. Nitrification: bacteria change ammonium to form nitrites (this can then be converted to nitrates) 2 3 denitrification 3) Nitrogen is then absorbed by plants and animals receive nitrogen by eating the plants

20 denitrification Decomposition of waste: some bacteria and fungi break down plant and animal waste to produce ammonia (and ammonium)

21 5 denitrification 5. Denitrification: some bacteria convert nitrates into N2 which returns to the atmosphere

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23 Nitrogen Cycle Video