Review

Carbon Cycle Nitrogen Cycle

Phosphorus Cycle

Carbon • Carbon is an essential component

of proteins, fats and carbohydrates, and therefore all organisms…. Like: lil bub, moon jellies, and weird trees

Carbon cycle

• The cycle is a process in which carbon is cycled between the atmosphere, land, water, and organisms

• Producers like plants convert CO2 in the atmosphere to carbohydrates during photosynthesis. They also emit some CO2 into the atmosphere during respiration.

• Consumers eat producers, and absorb carbon from the food through their diet

• This food gets broken down and digested during cellular respiration, and some carbon is released back into the atmosphere as CO2.

• Some carbon gets transformed into carbonate, which makes up bones, shells, or limestone rock and takes longer to process through the cycle.

• Or carbon that is converted into fats/oils/proteins in an organism gets returned to the soil when it dies.

Humans and the carbon cycle• Sometimes, when the organism dies and the carbon

gets returned to the earth, if the conditions are right, carbon gets deposited into the form of coal or oils known as fossil fuels.

• Humans figured out that burning these creates heat or energy. When they do this, the carbon is released back into the atmosphere as CO2.

• If this happens at a rate that’s faster than carbon can be absorbed, too much CO2 stays in the air.

• Too much CO2 prevents the sun’s solar rays from leaving our atmosphere… and heats up our whole earth.

• This can lead to: mass extinctions, food scarcity, economic difficulty, sea level rise and displacement of whole cities… etc.

• We should stop messing with the carbon cycle

Nitrogen • 5th most abundant element in the universe.• Makes up 78% of the gases in the atmosphere• All organisms need nitrogen to build proteins – which

are of course used to build cells.• It has to be fixed or altered before organisms can use it

though.• Nitrogen-fixing bacteria can do this. These bacteria are

a crucial part of the nitrogen cycle• Sometimes these bacteria look like hairy swimming

cucumbers:

Nitrogen Cycle• Process in which nitrogen is transferred from the atmosphere to

bacteria and other organisms.

• These special bacteria live on the roots of legumes, like beans, peas and clover. These are pretty healthy, protein rich plants btw.

• Or some bacteria just live in the soil, which is how non-legume plants get nitrogen.

• The plants give the bacteria sugar, and the bacteria make nitrate

• Excess nitrate goes into the soil

• Animals get nitrate from eating producers (plants), or other animals.

Thanks Bacteria!

• So we know nitrogen-fixing bacteria convert nitrogen from the atmosphere, where it exists as N2, and convert it into a usable form called nitrate.

• Other bacteria ALSO decompose dead things (these are known as decomposers), which releases nitrogen back into the atmosphere.

Humans and the nitrogen cycle• Mostly, we add LOTS of nitrogen to the system by putting in into fertilizers.

This washes into bodies of water causes algae to grow sucks up all the oxygen causes other life to die = eutrophication

• We also release nitrogen into the atmosphere by burning fossil fuels, because nitrogen is a part of all living matter, and fossil fuels came from living things.

• Nitrogen released from fossil fuels goes into the atmosphere as N2O (nitrous oxide)

• Considered over a 100-year period, it has 310 times more impact per unit weight (global warming potential) than carbon dioxide according to the (EPA).

• Then that whole climate change, everything is messed up-thing happens again.

Mental Break!

Phosphorus

• Phosphorus is a part of many molecules that make up the cells of living organisms.

• It is essential in making teeth and bones, like these:

Phosphorus cycle• The movement from P to the environment to organisms and back

– it does not normally occur in the atmosphere as a gas, so this process is slow.

• Phosphorus can enter soil and water through a few ways:

• Rock erosion -> goes into soil and water

• Plants absorb these phosphates

• Excess phosphorus goes back into the soil from waste, or dead things.

Humans and the Phosphorus Cycle

• The process of mining phosphorus (or anything) is not good for the environment. See:

Phosphorus and nitrogen in fertilizer and washes into the watershed causing eutrophication