Biogeochemical Cycles

Water Cycle Defined: Movement of water through the Earth and its atmosphere 75% of the Earth is covered in water Less than 1% is drinkable. Most water is salty or frozen

Water Cycle Pathway Water vapor starts to cool…condensation occurs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water vapor starts to cool…condensation occurs Condensation: process where water vapor turns into a liquid Evaporation: Heat changes water from a liquid to a gas Transpiration: Water evaporates from the leaves of plants through openings called stomata Precipitation: Rain, snow, sleet, or hail falls when water drops become heavy Runoff: Water runs down hill into rivers, lakes, streams, oceans… Infiltration: Water soaks into the soil and collects as groundwater

Oxygen Cycle Autotrophs: Release O2 into atmosphere by photosynthesis Most life needs O2 for cellular respiration Creates ATP (energy) for cells

Carbon (C) Cycle Plants Decomposers Animals Human Contribution glucose glucose glucose CO2 glucose glucose glucose Carbon Human Contribution Release excess CO2 into atmosphere when fossil fuels (coal, oil, natural gas) are burned for energy Cycle is out of balance Plants Absorb CO2 for photosynthesis Release glucose (C6H12O6) after photosynthesis Decomposers Obtain glucose by feeding on dead organisms Carbon released in their waste Animals Glucose passed up the food chain CO2 exhaled into atmosphere

Phosphorus (P) Cycle Phosphorus needed to make ATP, DNA, lipids Problem: No phosphorus in atmosphere Step 1: Phosphorus released by weathering of rocks Step 2: Producers absorb P through their roots Step 3: Consumers ingest P Step 4: Decomposers obtain P when feed on the dead. Step 5: Decomposers release P within waste back into soil or water Cycle repeats P P P P P

Phosphorus (P) Cycle Human Contribution P P P P Adding excess P from fertilizers P washes into lakes, etc… Excess P causes extreme plant & algae growth P P

Nitrogen (N) Cycle Nitrogen needed to build nucleic acids (DNA/RNA) Step 4: Producers absorb N through their roots Step 5: Consumers ingest N through the food chain Step 6: Decomposers obtain N from dead organisms… return N to soil in their waste Nitrogen needed to build nucleic acids (DNA/RNA) Problem: Nitrogen in atmosphere (N2) is unusable Step 1: Bacteria in soil convert N2 into usable forms Step 2: Bacteria absorb usable N Step 3: Bacteria release N waste into air N2 N N N N N Usable N Usable N Nitrogen fixation

Nitrogen (N) Cycle How does lightning help? O2 O O N2 N N N N2 N O O Energy breaks atmospheric nitrogen into Nitrogen oxide Nitrogen oxide falls in rain to soil

Review Name and define the 6 stages of the water cycle. How is oxygen released into the atmosphere? In which cellular process is oxygen removed and used from the atmosphere? What are the 4 major types of organic molecules? In which cellular process is carbon dioxide released into the atmosphere? How are humans disrupting the carbon cycle? Which objects release phosphorus over time? How are humans disrupting the phosphorus cycle? Which organisms help convert gaseous nitrogen into a usable form of nitrogen in the nitrogen cycle? How do plants obtain nitrogen? Of the major molecules that we have studied this year, which ones contain nitrogen and/or phosphorous?