Cycles of the Earth Biogeochemical Cycles Dead Zone

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Cycles of the Earth & Biogeochemical Cycles Dead Zone Slides 122 -136

Cycles of the Earth & Biogeochemical Cycles Dead Zone Slides 122 -136

Humans affect the nitrogen cycle • Haber-Bosch process = production of fertilizers by combining

Humans affect the nitrogen cycle • Haber-Bosch process = production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia – Humans overcame the limits on crop productivity • Fixing atmospheric nitrogen with fertilizers – Increases emissions of greenhouse gases and smog – Washes calcium and potassium out of soil – Acidifies water and soils – Moves nitrogen into terrestrial systems and oceans – Reduces diversity of plants adapted to low-nitrogen soils – Changed estuaries and coastal ecosystems and fisheries

Humans affect the phosphorus cycle • Mining rocks for fertilizer moves phosphorus from the

Humans affect the phosphorus cycle • Mining rocks for fertilizer moves phosphorus from the soil to water systems • Wastewater discharge also releases phosphorus • Runoff containing phosphorus causes eutrophication of aquatic systems – Produces murkier waters – Alters the structure and function of aquatic systems – Do not buy detergents that contain phosphate

Solutions to the dead zone • The Harmful Algal Bloom and Hypoxia Research and

Solutions to the dead zone • The Harmful Algal Bloom and Hypoxia Research and Control Act (1998) – Called for an assessment of hypoxia in the dead zone • Solutions outlined included: – Reduce nitrogen fertilizer use in Midwestern farms – Apply fertilizer at times which minimize runoff – Use alternative crops and manage manure better – Restore wetlands and create artificial ones – Improve sewage treatment technologies – Evaluate these approaches

Central Case: The Gulf of Mexico’s “Dead Zone” • Gulf of Mexico brings in

Central Case: The Gulf of Mexico’s “Dead Zone” • Gulf of Mexico brings in 600 million kg/year shrimp, fish, and shellfish • Gulf “dead zone” = a region of water so depleted of oxygen that kills or drives away marine organisms • Hypoxia = low concentrations of dissolved Dead Zones Part 1 oxygen water Dead Zones part 2 • Caused by fertilizer, runoff, 'Dead Zones' Are Increasing in Our sewage Oceans WORLDWIDE!

QUESTION: Review The term “system” includes all of the following, except: a) A network

QUESTION: Review The term “system” includes all of the following, except: a) A network of relationships among various components b) The various components tend to minimize interactions c) Energy, matter, and information are exchanged between components d) Energy and matter are valuable inputs to the system

QUESTION: Review Which of the following describes a positive feedback loop? a) It drives

QUESTION: Review Which of the following describes a positive feedback loop? a) It drives a system towards an extreme b) It stabilizes the system c) It causes the system to move in opposite directions at the same rates d) It causes the system to maintain a constant condition

QUESTION: Review Which of the following is a correct statement? a) Energy and matter

QUESTION: Review Which of the following is a correct statement? a) Energy and matter flow in one direction only b) Energy and matter both cycle repeatedly c) Energy flows in one direction, while matter recycles d) Matter flows in one direction, while energy recycles

QUESTION: Review What is the definition of “net primary production”? a) Assimilation of energy

QUESTION: Review What is the definition of “net primary production”? a) Assimilation of energy by heterotrophs b) Elements and compounds that are required for survival c) Energy remaining after respiration that is used to generate biomass d) Assimilation of energy by autotrophs

QUESTION: Review Which biogeochemical cycle comprises 78% of our atmosphere, and is contained in

QUESTION: Review Which biogeochemical cycle comprises 78% of our atmosphere, and is contained in proteins, DNA and RNA? a) b) c) d) Carbon Nitrogen Water Phosphorus

QUESTION: Review Which biogeochemical cycle is being affected by damming rivers, and altering the

QUESTION: Review Which biogeochemical cycle is being affected by damming rivers, and altering the surface and vegetation? a) b) c) d) Carbon Nitrogen Water Phosphorus

QUESTION: Review Which rock is formed from magma; for example, granite and basalt? a)

QUESTION: Review Which rock is formed from magma; for example, granite and basalt? a) b) c) d) Sedimentary Igneous Metamorphic Phosphorus

QUESTION: Weighing the Issues Who should pay for cleanup of the nitrate entering the

QUESTION: Weighing the Issues Who should pay for cleanup of the nitrate entering the Gulf of Mexico? a) b) c) d) The federal government State governments Fishermen Farmers responsible for fertilizer runoff

Decreasing pollution • Scientists, farmers and policymakers are encouraged to – Decrease fertilizer use

Decreasing pollution • Scientists, farmers and policymakers are encouraged to – Decrease fertilizer use – While safeguarding agriculture • Offering insurance and incentives • Using new farming methods • Planting cover crops • Maintaining wetlands • There have been some successes – Despite a lack of funding