Cycles of the Earth Biogeochemical Cycles Sulfur Cycle

Cycles of the Earth & Biogeochemical Cycles Sulfur Cycle, GAIA Hypothesis Slides 107 -121

The Sulfur cycle Sulfur trioxide Water Acidic fog and precipitation Sulfuric acid Ammonia Oxygen Sulfur dioxide Ammonium sulfate Hydrogen sulfide Plants Dimethyl sulfide Volcano Industries Animals Ocean Sulfate salts Metallic sulfide deposits Decaying matter Sulfur Hydrogen sulfide Fig. 3 -32, p. 78

The Sulfur cycle QUESTION: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle?

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.

Video Recap • Water Cycle-http: //www. youtube. com/watch? v=v. YBj. PE 0 wekw • Carbon Cycle-http: //www. youtube. com/watch? v=mld. BE 9 Ee 3 z. Y • Phosphorous Cycle-http: //www. youtube. com/watch? v=le. Hy. Y_8 n. Rs • Nitrogen Cycle-http: //www. youtube. com/watch? v=DP 24 Bce. Owt 8 • Sulfur Cycle- https: //www. youtube. com/watch? v=Bz. Pe. A 9 o. QNl 8 • Phosphorous & Sulfur Cyclehttps: //www. youtube. com/watch? v=Gvu_NPPX 9 Vc&index=35&list=PLzaf. DLb T 9 mqw. Ppo-tp 3 Zr. Wn. V-RXgu 9 e. I 2

Biogeochemical cycles of other minerals, such as calcium and magnesium, are similar to the phosphorus cycle.

The Gaia Hypothesis: Is the Earth Alive? • Some have proposed that the earth’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes. – The strong Gaia hypothesis: life controls the earth’s life-sustaining processes. – The weak Gaia hypothesis: life influences the earth’s life-sustaining processes. – http: //www. youtube. com/watch? v=44 yi. Tg 7 c. OVI

Gaia Hypothesis • The Gaia hypothesis states that the temperature and composition of the Earth's surface are actively controlled by life on the planet. • It suggests that if changes in the gas composition, temperature or oxidation state of the Earth are caused by extraterrestial, biological, geological, or other disturbances, life responds to these changes by modifying the abiotic environment through growth and metabolism. • In simplier terms, biological responses tend to regulate the state of the Earth's environment in their favor.

Explain how human impact is affecting biogeochemical cycles. • People are affecting Earth’s biogeochemical cycles by shifting carbon from fossil fuel reservoirs into the atmosphere, shifting nitrogen from the atmosphere to the planet’s surface, and depleting groundwater supplies, among other impacts • Policy can help us address problems with nutrient pollution.

Compare and contrast how carbon, phosphorus, nitrogen, and water cycle through the environment. • A source is a reservoir that contributes more of a material than it receives, and a sink is one that receives more than it provides. • Water moves widely through the environment in the water (hydrological) cycle. • Most carbon is contained in sedimentary rock. Substantial amounts also occur in the oceans and in soil. Carbon flux between organisms and the atmosphere occurs via photosynthesis and respiration. • Nitrogen in a vital nutrient for plant growth. Most nitrogen is in the atmosphere, so it must be “fixed” by specialized bacteria or lightning before plants can use it. • Phosphorus is most abundant in sedimentary rock, with substantial amounts in soil and the oceans. Phosphorus has no appreciable atmospheric pool. It is a key nutrient for plant growth.

Human impacts on the hydrologic cycle • Removing forests and vegetation increases runoff and erosion, reduces transpiration and lowers water tables • Irrigating agricultural fields depletes rivers, lakes and streams and increases evaporation • Damming rivers increases evaporation and infiltration • Emitting pollutants changes the nature of precipitation • The most threatening impact: overdrawing groundwater for drinking, irrigation, and industrial use – Water shortages create worldwide conflicts

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 • The missing carbon sink: 1 -2 billion metric tons of carbon are unaccounted for – It may be taken up by plants or soils of northern temperate and boreal forests