Abiotic chemicals (carbon dioxide, Heat oxygen, nitrogen, Solar Heat minerals) Heat Solar energy Heat Heat Producers (plants) Decomposers (bacteria, fungi) Figure 3.14 Natural capital: the main structural components of an ecosystem (energy, chemicals, and organisms). Matter recycling and the flow of energy—first from the sun, then through organisms, and finally into the environment as low-quality heat—links these components. Fig 4.8 in Raven & Berg During photosynthesis, producers use the energy from sunlight to make complex molecules from carbon dioxide and water. Consumers obtain energy when they eat producers or consumers that ate producers. Wastes and dead organic material supply decomposers with energy. During every energy transaction, some energy is lost to biological systems as it is dispersed as heat. Consumers (herbivores, carnivores) Heat Heat Fig. 3-14, p. 61

Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Biosphere Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Figure 3.7 Natural capital: life on the earth depends on the flow of energy (wavy arrows) from the sun through the biosphere and back into space, the cycling of crucial elements (solid arrows around ovals), and gravity, which keeps atmospheric gases from escaping into space and helps recycle nutrients through air, water, soil, and organisms. This simplified model depicts only a few of the many cycling elements. Heat in the environment Heat Heat Heat

The Carbon Cycle Organisms must have carbon available (proteins, carbohydrates, etc) C makes up 0.037% of the atmosphere in the form of CO2 C in ocean dissolved CO2 C in land – rocks, limestone

What is it? The global movement of Carbon between the abiotic environment, including the atmosphere and ocean, and organisms Fig 6.2, p. 106

Photosynthesis takes CO2, incorporate it into complex chemical compounds (ex. Glucose) Photosynthesis incorporates C from abiotic environment into the biological compounds of producers. C is recycled back when compounds are used for cellular respiration by the producer or by a consumer that eats the producer Cycle – CO2 in atmosphere  producer uses CO2  producer makes compounds  producer uses compounds for cellular respiration OR consumer eats producer Also happens in aquatic ecosystems with dissolved CO2

Sometimes C is not recycled back for a long time eg. Trees  coal beds shells  limestone Sometimes C is recycled back into atmosphere through combustion eg. coal, oil, natural gas (fossil fuels) C + O  CO2 + water + heat + light

CARBON CYCLE Fig 6.2 in Raven & Berg

Effects of Human Activities on Carbon Cycle We alter the carbon cycle by adding excess CO2 to the atmosphere through: Burning fossil fuels. Burning Tropical Forests. Clearing vegetation faster than it is replaced. Adding CO2 at a rate greater than the natural C cycle can handle Ocean and vegetation are C sinks – C is temporarily taken up Rise in CO2 in the atmosphere may be causing global warming (rise in sea levels, extinction)

Nitrogen Cycle

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

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.

Nitrogen Fixation This is the first step of the nitrogen cycle Specialized bacteria convert gaseous (atmospheric) nitrogen to ammonia that can be used by plants. This is done by nitrogen fixing bacteria Ex. cyanobacteria or bacteria living in the nodules on the root of various plants.

Nitrification Assimilation Ammonia or Ammonium is converted to nitrate Performed by nitrifying bacteria. Assimilation Conversion of inorganic nitrogen (biological molecules containing nitrogen) to the organic molecules of organisms

Ammonification Denitrification After nitrogen has served its purpose in living organisms decomposing bacteria convert the nitrogen-rich compounds, wastes, and dead bodies into simpler compounds such as ammonia. Denitrification Nitrate ions and nitrite ions are converted into nitrous oxide gas and nitrogen gas. This happens when a soil nutrient is reduced and released into the atmosphere as a gas.

Phosphorus Bacteria not as significant a role in P cycle P does not form compounds in gaseous state  P does not enter atmosphere The P cycle is slow and phosphorus is usually found in rock formations and ocean sediments. Enters soil by erosion of P containing rocks Enters aquatic communities via algae, fish then eat algae, then die  decompose, re-enters

Phosphorous Cycle

Effects of Human Activities on the Phosphorous Cycle We remove large amounts of phosphate from the earth to make fertilizer. We reduce phosphorous in tropical soils by clearing forests. We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

Sulfur Cycle Bacteria drive the S cycle Largest pool of Sulfur on the planet is in sedimentary rocks. S containing rocks erode releasing S into soil and water via run-off. S enters atmosphere several ways. Forest fires, dust storms, volcanoes Does not remain in atmosphere long Small amount in atmosphere, but lots of cycling through Bacteria – convert different forms of sulfur, in both oxygen rich and oxygen deficient environments – similar to N cycle

The Sulfur Cycle Figure 3-32

Effects of Human Activities on the Sulfur Cycle We add sulfur dioxide to the atmosphere by: Burning coal and oil Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.

Hydrologic Cycle Water is essential to life Substantial part of mass of most organisms Constantly cycling Oceanatmospherelandocean ALL water is cycled through Precipitation, evaporation, transpiration Precipitation – rain, snow, sleet, hail – moves from atmosphere to land Evaporation – from water (ocean, lakes, rivers, streams) to atmosphere Transpiration – water from plants to atmosphere (ex. Tree absorbs water from soil, goes to leaves, transpires) Water may evaporate directly from land to atmosphere

Humans and the Hydrologic Cycle Positive – use for hydroelectric Negative – air pollution potentially affecting hydrologic cycle Aerosols in atmosphere affect cloud development, may not release precipitation as readily

Biogeochemical Cycles Wrap Up Living things depend on the abiotic environment to supply essential materials C, N, S, P, water