Carbon, Nitrogen, & Water Cycles Guided Notes

CHEMICAL CYCLING IN ECOSYSTEMS 1. What gets recycled in our ecosystem? Carbon Nitrogen Water

2. What Is Carbon? An element The basis of life on earth Found in rocks, oceans, atmosphere

The Carbon Cycle 3. The same carbon atoms are used repeatedly on earth. They cycle between the earth and the atmosphere.

The Carbon Cycle (Terrestrial) DRAW THIS ON YOUR OWN PAPER! Fig. 4-28 p. 84-85

The Carbon Cycle (Aquatic) DRAW THIS ON YOUR OWN PAPER! Fig. 4-28 p. 84-85

Carbon Cycle 4. Producers: Plants take in CO2 & make sugar by photosynthesis. Consumers: Animals eat plants to get energy (respiration) from sugar & make proteins from the carbon. Breathe out CO2 as a waste product of respiration. Animals die and dentritus (decomposers) break down carbon and other elements back into the soil & air for plants to use again.

Plants Use Carbon Dioxide 5. When plants pull carbon dioxide (CO2) from the atmosphere and use it to make food (photosynthesis), the carbon becomes part of the plant (stored food).

Animals Eat Plants 6. When organisms eat plants, they take in the carbon and some of it becomes part of their own bodies.

Plants and Animal Die 7. When plants & animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere. Some are not decomposed fully and end up in deposits underground (oil, coal, etc.).

Carbon Slowly Returns to Atmosphere 8. Carbon in rocks and underground deposits is released very slowly into the atmosphere. This process takes many years.

9. Humans affect the carbon cycle Burning fossil fuels moves carbon from the ground to the air. Cutting forests and burning fields moves carbon from vegetation to the air. Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years. It is the driving force behind climate change (global warming)

The Nitrogen Cycle 10. Nitrogen comprises 78% of our atmosphere It is contained in proteins, DNA and RNA Nitrogen cycle = describes the routes that nitrogen atoms take through the environment Nitrogen gas in the atmosphere (N2) cannot be used by organisms Has to be in the form of ammonia (NH3) or nitrates (NO3-)

11. Nitrogen Fixation by bacteria Plants need nitrogen but cannot take it in from the air. Bacteria in the soil on the roots of plants take in nitrogen (N2) and make ammonia (NH4) which plants can then use to get nitrogen.

Nitrogen Cycle (N) DRAW THIS ON YOUR OWN PAPER!

12. Humans affect the nitrogen cycle: Fixing atmospheric nitrogen with fertilizers Increases emissions of greenhouse gases and smog Acidifies water and soils Moves nitrogen into terrestrial systems and oceans Reduces diversity of plants adapted to low-nitrogen soils Changes estuaries & coastal ecosystems & fisheries

Hydrologic (Water) Cycle DRAW THIS ON YOUR OWN PAPER! Fig. 4-27 p. 83

13. Human impacts on the hydrologic cycle Deforestation increases runoff & erosion, reduces transpiration & lowers water tables Irrigating agricultural fields depletes rivers, lakes, & streams Damming rivers increases evaporation Overdrawing groundwater for drinking, irrigation, & industrial use Water shortages create worldwide conflicts 18 18