Chapter 6 notes - part 1,2,3
Earth background
- Earth has 4 unique : liquid water, life, plate tectonics, triple points. - Atmosphere of the Earth was low in oxygen before 2.3 billion years ago. - Oceans were filled with unoxidized iron. - Earth don't have a similar atmosphere as Mars, Mercury, and Venus. Early organisms on Earth
- Prokaryotes: A nucleus and lacked organelles, live singly or end to end chains cannot form 3D. Get energy from waste products of CO2 and alcohol. Can easily reproduce. - Eukaryotes - Permits multicellular body structure of plants, animals, and fungi. It's larger cells then prokaryotes. Used oxygen for respiration. Life and global chemical cycles
- Micronutrients - nutrients required by humans and other organisms throughout life in small quantities to orchestrate a range of physiological functions. - Macronutrients - 24 elements required by all organisms and include oxygen, carbon, hydrogen, nitrogen, phosphorus and surfur. Too much of some elements can be toxic, too little of some element can limit growth and development. Neutral is some elements are neutral for life. General aspects of biogeochemical cycles
- Oxygen and nitrogen are 2 chemicals cycle quickly and are readily regenerated for biological activity. - They typically have a gas phase. They're soluble and carried by the hydrologic cycle. - Phosphorus are elements are relatively immobile and returned by geological processes, typically lack a gas phase and insoluble. - Modern technology transfer rate of elements into air, water and soil altered. - Lights are the most required nutrients, heaviest is iodine with atomic weight of 53. - Chemical is stored - donating compartment is a source, receiving compartment is a sink, amount of time an atom spends in any compartment is called its residence time. Types of boundaries
- Divergent plate boundary - plates move away from another, known as sea floor spreading, produces ocean basins. - Convergent plate boundary - plates move toward each other, heavier ocean plates meet lighter continental plates collide. - Transform - plates slides past another, LA moving towards SF. San Andreas Fault in California; boundary of Na and Pacific plates. The rock cycle
- Rocks classified as - igneous, sedimentary, metamorphic. - Depends on the tectonic cycle for energy and the hydrologic cycle for water. - Chemical weathering occurs when weak acids in water dissolve chemicals from rocks. - Physical weathering ( freeze, thaw) produces sediment such as gravel, sand and silt. The nitrogen cycle
- Nitrogen fixation - process of converting atmosphere N to NO3- or NH4+ - Denitrification - process of releasing fixed N back to molecular N. - Almost all organisms depend on N converting bacteria. Some have formed symbiotic relationships in the roots of plants or stomach on animals. - N combines with O at high temperature - creates oxides - oxides of N a source of air pollution. The phosphorus cycle
- Doesn't have a gaseous phase-rate of transfer slow. - Phosphorus is a factor that in Big 6 required for life. - Enters biota through uptake as phosphate by plants, algae and some bacteria. - Returns to soil when plants die or is lost to oceans via runoff. - Returns to land via ocean feeding birds. - Guano - deposits major source of P for fertilizers. |
Rise oxygen
- Photosynthesis: CO2 and H2O are combined in presence of light to create sugars and free oxygen. Early photosynthesizers included stromatolites. - Took 2 billion years before oxygen started to accumulate in atmosphere. Evolution of biosphere
- Biosphere started to change drastically after presence of eukaryotes and oxygenated atmosphere. - 700-500 years ago plants, animals, and fungi evolved. They in turn, continued to alter the biogeochemical cycles on Earth. Biogeochemical cycles
- A biogeochemical cycle is a pathway by which a chemical element or molecule moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth. A cycle is a series of change which comes back to the starting point and which can be repeated. The geologic cycle
- Rocks and soil - continually created, maintained, changed and destroyed over the last 4.6 billion years. - Group of cycles - tectonic, hydrologic, rock, and biogeochemical. The tectonic cycle
- Around 100 km thick and broken into several plates. - The slow movement of plates is called plate tectonics. ( 2-15cm/yr) - Has large scales effects - Location and size of contiments, alterations in climate - Ecological islands, area of volcanic activity and earthquakes. The hydrologic cycle
- Hydrologic cycle is the transfer of water from oceans to the atmosphere to the land and back to the oceans. - Driven by solar energy: * Evaporation of water from ocean * Precipitation of water on land. * Transpiration of water by plants * Evaporation of water from land * Runoff from streams, rivers, and subsurface groundwater. - Total H2O on Earth = 1.3 billion km^2 * 97% in oceans * 2% in glaciers and ice caps * 0.001% in atmosphere * The rest in fresh water on land - Drainage basin - the fundamental unit of the landscape, the area that contributes surface runoff to a particular stream or river, vary in size. The carbon silicate cycle
- Cycle carbon involved with cycle silicon. - Weak carbonic acid falls as rain and weathers silicate rich rocks. - Releases Ca ^2 + HCO3-. - Transferred to oceans and used by marine animals to construct shells. - Shells deposited on sea floor become part of red rock layer and return to surface in subduction zones. - Magma containing CO2. - Rainwater dissolves CO2 and removes it from the atmosphere as H2CO3. - Weathering and erosion of silica rocks release Ca+- and HCO3- - Enrupting volcanoes + CO2 to the atmosphere. |