The Cycling of Matter Energy flows in one direction starting as solar radiation and finally leaving as heat Nutrients Cycle! Absorbed by organisms from the soil and atmosphere Circulate through trophic levels Released back to the ecosystem

Biogeochemical Cycles Around 40 elements cycle through ecosystems All have organic and inorganic phases Major Cycles: water, carbon, nitrogen, sulphur, and phosphorus Shared Characteristics: Very different than energy Energy is eventually lost Matter is finite and recycled Death-Decompose- nutirents released- taken up by plants again. (biogeochemical)

The Carbon Cycle Where is carbon stored? (sinks) Organic Inorganic Organisms (biomass) Fossilized Life (fossil fuels) Inorganic Sedimentary Rock (locked up for millions of years) Oceans (dissolved or locked up as carbonates) Soil Small amount in the atmosphere (live measurement)

Carbon Flows Cycles between living and non living Fixed by photosynthesis and returned to the atmosphere by respiration Also released when dead organisms decompose Also released through the burning of fossils fuels Photosynthesis = Carbon Fixation

Humans and the Carbon Cycle Additions Global emissions from fossil fuel burning is about 5.5 GtC (10^9 tonnes) 20%Natural gas; 40% Coal, 40% Oil Another 1.6 GtC are added through deforestation That is 7.1 GtC/year Uptake New forest growth takes up ~0.5GtC Oceans/phytoplankton take up ~ 2.4 GtC There is about 1-1.8 GtC we aren’t sure about Since the pre-industrial period we have added 200GtC to the atmosphere

The Nitrogen Cycle Nitrogen is essential for proteins and DNA so who needs it? Nitrogen Fixation: When atmospheric N2 is made available to plants. Goes from gaseous N to ammonia. (5 options) 1. Free living nitrogen fixing bacteria in soil (Azotobacter) 2. Symbiotic bacteria in root nodules of legumes (Rhizobium) 3. cyanobacteria (important to rice production) 4. Lightning oxidizes nitrogen gas to nitrate 5. Haber Process: Nitrogen and Hydrogen combined under pressure with iron catalyst (fertilizer production)

The Nitrogen Cycle Nitrification Denitrification Decomposition Some bacteria convert ammonia to nitrite Others convent nitrite to nitrate Plant roots readily absorb nitrates Denitrification Other bacteria often associated with water logged or low oxygen soil reverse the process and Nitrogen gas is returned to the atmosphere. Decomposition Also provides nitrogen for uptake by plants Way more than nitrogen fixation Assimilation After uptake Nitrogen is used in Building complex molecules

Humans and the Nitrogen Cycle Removal of animals and plants for food removes nitrogen from the system The Nitrogen is lost because it ends up in the human sewage system instead of the ecosystem Fertilizer Haber process makes more nitrogen Planting legumes can increase nitrogen Cultural Eutrophication

Phosphorus cycle Very slow Limited amount found in the soil (On Human time scale it flows in one direction from the land to the oceans) Limited amount found in the soil Limiting factor for plant growth Excess causes prolific plant growth algal blooms in water (Eutrophication) We mine the phosphate out of rock and add it to fertilizers and detergents

Do we have phosphates in our bodies?

The Phosphorous Cycle Is Phosphorous ever a gas in the air?

Sulfur cycle Natural sources of Sulfur (enter atm) Hydrogen sulfide (swamps/volcanoes) Sulfur dioxide SO2 (volcanoes) Marine Algae produce DMS (dimethyl sulfide) Comes out of decaying material Reacts in atmosphere to create hydrogen sulfate (H2SO4) sulfuric acid (acid rain)

The Sulfur Cycle

Effects of Human Activities on the Sulfur Cycle We add sulfur dioxide to the atmosphere in 3 ways: We burn coal and oil to produce electricity. Refine petroleum to make gasoline Convert sulfur containing mineral ore into free-metals ex: Pyrite is Iron Sulfide, to get Iron sulfur is released