Biogeochemical Cycling PDF

Biogeochemical cycling involves Biological, geologic and chemical interactions 5 major cycles: Carbon, Nitrogen, Phosphorus, Sulfur and Water (hydrologic) I. The Carbon (C) cycle - Global circulation of C between living and non-living environments Major processes: - Photosynthesis - CO2...

Biogeochemical cycling involves Biological, geologic and chemical interactions 5 major cycles: Carbon, Nitrogen, Phosphorus, Sulfur and Water (hydrologic) I. The Carbon (C) cycle - Global circulation of C between living and non-living environments Major processes: - Photosynthesis - CO2 dissolving into ocean - Respiration - Soil, in particular - Combustion of fossil fuels II. The Nitrogen (N) cycle - N needed for proteins and nucleic acids (DNA) - Atmosphere is 78% N~2~ but most cannot use this form - Five steps and every transformation need to use bacteria - N pollution in natural environments causes eutrophication (phú dưỡng), over-fertilization of forests **Planetary boundaries**: environmental limits within which humanity can safely operate. - **Climate change**: CO~2~ concentration, energy balance between Earth and space - **Atmosphere aerosol loading** (amount of air pollutants in the atmosphere) - **Stratospheric ozone depletion** (ozone concentration) - **Change in biosphere integrity** (functional diversity loss and speed of extinction) - **Land-system change** (deforestation) - **Ocean acidification** - **Freshwater use** (amount of water available for humans animals and plants) - **Biogeochemical flows** (P and N outflow from fertilizers) - **Introduction of novel entities** (introduction of synthetic chemicals, ex: plastics) III. The hydrologic cycle Over 71% of the earth's surface is covered by water Oceans contain 97%. Distribution of water is not static: Heat, Evaporation, Clouds, Precipitation (all the water comes from the sky) IV. Solar radiation Fuels = captured solar energy Albedo: The reflectance of solar energy off earth's surface Dark colors = low albedo (VD: Forests and ocean) Light colors = high albedo (VD: Ice caps) V. The atmosphere Content - 21% Oxygen - 78% Nitrogen - 1% Argon, Carbon dioxide, Neon and Helium Greenhouse gases (CFCs, CO~2~, CH~4~) Interaction atmosphere & solar energy weather & climate Atmosphere Layers (5) - **Troposphere (0--12km)** Where weather occurs Temperature decreases with Altitude - **Stratosphere (12--50km)** Temperature increases with Altitude - very stable Ozone layer absorbs UV Where jets fly - **Mesosphere (50--80km)** - **Thermosphere (80--500 km)** - **Exosphere (500km and up)** VI. Coriolis Effect Influence of the earth's rotation on movement of air and fluids Turns them Right in the Northern Hemisphere Turns them Left in the Southern Hemisphere VII. The global ocean Prevailing winds produce ocean currents and generate gyres Ocean Conveyor Belt: Affects regional and possibly global climate VIII. Weather and climate **Weather**: The conditions in the atmosphere at a given place and time **Climate**: The average weather conditions that occur in a place over a period of years 2 most important factors: temperature and precipitation (lượng mưa) IX. Internal Planetary Processes **Plate Tectonics**: study of the processes by which the lithospheric plates move over the asthenosphere **Plate Boundary**: where 2 plates meet **Divergent**: Two plates move apart **Convergent**: Two plates collide **Transform**: Plates move horizontally, opposite but in parallel 1. Convergent Plates 3 combinations - Oceanic crust vs. oceanic crust Subduction of one plate Ex: Japanese Islands - Oceanic crust vs. continental crust (VD: Đài Loan) - Continental crust vs. continental crust (VD: Himalayas) **Earthquakes:** Caused by the release of accumulated energy as rocks in the lithosphere suddenly shift or break. - Occur along faults - Energy released as seismic wave - Richter scale measures magnitude - Landslides and tsunamis are side effects **Tsunami**: Giant undersea wave caused by an earthquake, volcanic eruption or landslide Travel \> 800 km/h **Volcanoes**: Magma pushes through plate reaching surface becoming lava Volcanoes occur at - Subduction zones (Indonesia) - Spreading plates (Atlantic rift) - Above hot spots (Hawaii)