The Cycling of Materials

Why Learn About This? Most minerals essential for life cycle between living things and the atmosphere or the ground Atmosphere—gases surrounding Earth Biosphere—living ‘layer’ of Earth Lithosphere—soil/rock layer of Earth Earth is a “closed” ecosystem The only thing in is sun (energy), the only thing out is some heat(energy)

Cycles in the Biosphere The law of conservation of mass states that matter is not created or destroyed. Therefore , natural processes cycle matter through the biosphere. Involves both matter in living organisms and physical processes in the environment. (e.g. weathering)

The Carbon Cycle All living things are composed primarily of carbon (organic) compounds Carbohydrates Proteins Lipids Nucleic acids

The Carbon Cycle - Processes Photosynthesis: Plants take in CO2 from the atmosphere and convert it into sugars, which are then used by other organisms (heterotrophs) Respiration: Organisms respire and release CO2 back into the atmosphere Combustion: CO2 is also produced by burning fossil fuels CO2 traps heat in the atmosphere, so the more CO2 in the atmosphere, the hotter the atmosphere, but we’ll talk more about this later…..

The Carbon Cycle - Processes Death and Decay: Decomposers release CO2 into the atmosphere when they break down organic compounds. Fossils fuels were produced by the decay of ancient organisms.

Carbon “Sinks” Storage Organisms – complex organic compounds Atmosphere – CO2, CO, CH4 Litter and Waste – complex organic compounds Fossil fuels - hydrocarbons Industry and vehicles – hydrocarbons and other organic compounds Oceans – shells CaCO3 Lithosphere – limestone CaCO3

Carbon Cycle Short Term Green plants and algae convert CO2 in the atmosphere along with water into carbohydrates. These carbohydrates are used as a source of energy for all other organisms CO2 is recycled when autotrophs and heterotrophs release it back into air during celllular respiration.

They are opposite

Carbon Cycle Long Term Carbon enters a long-term cycle when organic material is buried underground and converted to peat, oil, coal or gas. This can take millions of years Carbon is released when fossil fuels are burned Carbon can also enter in a long term cycle in the form of calcium carbonate (found in shells of marine animals) when they fall to the ocean floor and create vast deposits of limestone rock. Carbon is released due to weathering and erosion

Carbon Cycle

The Nitrogen Cycle Nitrogen is an important element for organisms! Nitrogen is found in all proteins, and all nucleic acids in all organisms! We all need nitrogen!

The largest concentration (pool) of nitrogen N2 is found in the atmosphere (78% of the gases in the atmosphere; 98% of the total nitrogen on Earth) Plants and animals cannot use nitrogen directly from the atmosphere!

Nitrogen Fixation: Taking Nitrogen from the Atmosphere Atmospheric nitrogen must be captured by nitrogen-fixing bacteria that live in the soil and plant roots and converted to ammonia. This process is called biological nitrogen fixation. Nitrogen can also be fixed into a useable form by lightning or the activities of factories in industry (manufacturing fertilizers)

Ammonification Nitrogen is returned to soil by urination and dead organisms. Decomposers break down the nitrogen from these to ammonia through ammonification. This is all well and good, but ammonia is toxic to most living cells…

Nitrification: Making Nitrogen Useable to Organisms Soil bacteria (nitrifying bacteria) convert ammonia into nitrites (NO2-) and nitrates (NO3-) through nitrification

Assimilation: Getting the Nitrogen into Organisms Beans, peas, clover and alfalfa use the nitrogen directly from the bacteria in their roots to make amino acids and nucleic acids. Other plants absorb nitrates from soil and convert into amino acids. Consumers get nitrogen when they eat plants or animals that contain it.

Denitrification: Returning Nitrogen to the Atmosphere Anaerobic denitrifying bacteria in the soil convert nitrates back into nitrogen N2 through denitrification which returns to atmosphere.

Nitrogen Cycle

The Phosphorus Cycle Phosphorus is essential for the growth and development of organisms. There is a short term and long term cycle. Short term is cycled from soil to producers to consumers. Waste and decomposition return it to soil to be used again. Long term is from sedimentation to form rocks and is released due to weathering and erosion Phosphorus may be present in only small amounts and can limit the growth of producers

Review of Basic Concepts in Nutrient Cycling

So, in conclusion…. Nutrients (chemicals) we (and other living things) need for life functions, often come from the ground or the air As we carry out life functions, these chemicals are returned to the air or the ground, and the cycles start over again Similar to chemicals, energy also moves through ecosystems, but we’ll talk about that later… …and that’s all for today, folks!!!