1. The Biogeochemical cycles

2. What is the Biosphere All living things and their habitats found in water, on land and in the air make up the biosphere. It can be considered the fourth ‘layer’ of the Earth; – The Lithosphere - a solid layer – The Hydrosphere - a liquid layer – The Atmosphere – a gaseous layer – The Biosphere – a layer of life

3. Biogeochemical cycles All the elements necessary for life are constantly recycled in the biosphere. This allows life to continue indefinitely. Some important cycles; – The water cycle – The phosphorous cycle – The nitrogen cycle – The carbon cycle – The oxygen cycle

4. The Carbon Cycle Life on earth is ‘carbon based’. Carbon provides the framework for proteins, fats and sugars that life relies on. Plants use photosynthesis to trap atmospheric carbon as sugar. This is then used by the plant, the animal that eats it and the decomposer that eats the animal, until the carbon is released as gas again (CO 2 ) or stored in the Earth.

5. Humans store and use carbon in our bodies, breath it out and create it when we burn wood and fossil fuels.

6. The Nitrogen Cycle Nitrogen is an important part of DNA, that contains biological information, and proteins, which are part of our muscles and our chemistry.

7. The Nitrogen Cycle Lightning converts some N 2 into nitrogen oxide. Bacteria, which trap N 2 from the atmosphere and create NH 3 (ammonia), NH 4 + (ammonium), nitrites (NO 2 -) and nitrates (NO 3 -). Plants use this nitrogen and produce more complex compounds (ex. DNA). Animals use the nitrogen through the food chain. Decomposers turn it into NH 4 +. Other bacteria convert it back to N 2 and release the nitrogen back to the atmosphere

8. Humans are part of the biological nitrogen cycle but also put nitrogen oxides into the atmosphere when we burn fossil fuels and spread fertilizer. This contributes to pollution, acid rain and the greenhouse effect.

9. The Phosphorous Cycle Phosphorous is essential to life. It is part of DNA, and needed for bones and shells. Phosphorus reacts with oxygen to form phosphates. This is the form phosphorus takes in nature. Plants can absorb this, then it moves through the food chain.

11. The Phosphorous Cycle Phosphate-containing rocks erode to small pieces. Plants absorb the phosphates, use it for life. Animals eat the plants, use the phosphorus. Dead plants and animals are decomposed. The Phosphorus returns to the soil. Organisms in water die and settle at the bottom. Sediment builds up over time. New rock is formed.