Cycles Today (9/26) we will…

Learn about the hydrologic and carbon cycle

Work on our projects (finish paragraphs and start on the rough draft) Learning targets

• Students will be able to relate how cycles drive the transfer of matter in systems

• Students will know each step of the hydrologic, carbon/oxygen, nitrogen and phosphorus cycle Biosphere

Biogeochemical cycles - Movement of matter between ecosystems biologically, geologically, and chemically

Matter on Earth is a closed system

Energy on Earth is open system Biosphere

Carbon Phosphorus Nitrogen Water Oxygen cycle cycle cycle cycle cycle

Heat in the environment

Heat Heat Heat Fig. 3-7, p. 55 Water Cycle Evaporation: Water on the surface of ponds, rivers, oceans, or land is heated by the sun and enters the atmosphere (vaporization of water).

Transpiration: evaporation of water from plants.

Condensation: Water vapor cools, condenses, and turns into clouds. Water Cycle

Precipitation: After water in the atmosphere cools, it condenses, then falls to Earth’s surface (rainfall).

Percolation: water soaks into the soil and becomes groundwater.

Run off: Water runs across the surface of Earth into rivers, lakes, and oceans. Human impact on the hydrologic cycle

Harvesting trees  decreased evapotranspiration  runoff or percolation increases  increase erosion or flooding

Paving over land  reduces percolation  increases runoff and evaporation

Water diversion for drinking, industries, irrigation Carbon and Oxygen Cycles Carbon cycle: the movement of carbon between the abiotic and biotic parts of the environment.

Animals, plants, and other photosynthesizing organisms play an important role in cycling carbon and oxygen through an ecosystem. Carbon and Oxygen Cycles

Plants use carbon dioxide (CO2) from the atmosphere to build organic molecules during photosynthesis.

During photosynthesis, oxygen is released into the atmosphere.

KNOW THE REACTION! Carbon and Oxygen Cycles

Respiration: oxygen is used to help break down glucose, releasing energy for the animal to use and carbon dioxide (CO2).

Plants are then able to use the CO2 for photosynthesis. KNOW THE REACTION! Carbon and Oxygen Cycles

Combustion: the burning of a substance, releasing carbon into the atmosphere.

Fossil fuels are formed from the remains of dead plants and animals, which are made of carbon.

The burning (combustion) of fossil fuels releases carbon dioxide (CO2) into the atmosphere.

We as humans burn fossil fuels, such as oil and coal, to generate electricity and to power vehicles. Effects of Human Activities on Carbon Cycle We alter the carbon cycle by adding excess CO2 to the atmosphere through: • Burning fossil fuels. • Clearing vegetation faster than it is replaced.

Figure 3-28 Today (9/27) we will…

Learn about the nitrogen and phosphorus cycles

Don’t forget to finish up your questions/food web drawing on your owl pellet lab!

Continue working on our project Nitrogen Cycle Nitrogen cycle - nitrogen circulates through the air, soil, water, and organisms in an ecosystem. Nitrogen Cycle, continued

Nitrogen fixation - bacteria convert nitrogen gas (N2), into ammonia (NH3)

Nitrogen-fixing bacteria live in soil and on the roots of some plants. Nitrogen Fixation Ammonification Ammonification - nitrogen from animal waste or decaying bodies (detritus) is decomposed into ammonia (NH3) and ammonium(NH4+) in soil by nitrogen fixing bacteria. Ammonification Nitrification

Nitrification - ammonium (NH4) from waste is converted to nitrite (NO2-) and then nitrate (NO3-) by nitrifying bacteria. Nitrification Assimilation Assimilation - plants absorb nitrogen. In turn, when an animal eats a plant, nitrogen compounds become part of the animal’s body. Assimilation Denitrification

Denitrification - nitrates (NO3-) are changed to nitrogen gas (N2) by denitrifying bacteria which returns to the atmosphere. Denitrification Effects of Human Activities on the Nitrogen Cycle We alter the nitrogen cycle by: • Adding gases that contribute to acid rain. • Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. • Contaminating ground water from nitrate ions in inorganic fertilizers. • Releasing nitrogen into the troposphere through deforestation. Effects of Human Activities on the Nitrogen Cycle Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.

Figure 3-30 The Nitrogen Cycle

•Fix ation  • A mmonia •N itrification  • N itrites  Nitrates •A ssimilation  • P roteins •A mmonification  • A mmonia • enitrification  D • N itrogen (gas) Phosphorous Cycle Phosphorus Cycle, continued

Phosphorus is often found in soil and rock as a part of calcium phosphate

Calcium phosphate dissolves in water and releases phosphate. Phosphorus Cycle The roots of plants absorb phosphates from the soil in order to survive. Phosphorus Cycle Humans and animals that eat plants reuse the organic phosphorus as a nutrient for life.

When the humans and animals die, the phosphorus is returned to the soil.

Effects of Human Activities on the Phosphorous Cycle Fertilizer - We remove large amounts of phosphate from the earth to make fertilizer.

Clear cutting - We reduce phosphorous in tropical soils by clearing forests.

Run off from farmland- We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers; causes algal blooms