Chapter 6 Notes
Earth is a Peculiar Planet:
Four unique characteristics:
Planets Near Earth:
Rise of Oxygen:
Early Organisms on Earth:
Prokaryotes:
Evolution of Biosphere:
Life & Global Chemical Cells:
Micronutrients:
Macnutrients:
Biochemical Cycles:
To complete a path a chemical takes through 4 major components of Earths System which is:
General Aspects of Biochemical Cycles:
Simplest Way to View a Cycle: Box & Arrow Diagram
Boxes:
Source:
Sink:
Residence Time:
Arrows:
Flow:
Flux:
Geological Cycle:
Geologic Cycle- Group of Cycles:
Tectonic Cycle:
Hydrologic Cycle:
Rock Cycle:
Carbon Cycle:
Carbon Silicate Cycle:
Nitrogen Cycle:
Phosphorus Cycle:
Four unique characteristics:
- Liquid water
- plate tectonics
- water available all 3 phases
- Life
Planets Near Earth:
- Inner planets are formed by gathering together off particle by gravitational force.
- We're in the perfect spot , which is close enough but not too far from the sun.
- We have inner terrestrial planets, and the outer gaseous planets.
- Earth has "environmental fitness" and it's unique atmosphere shows it has life.
Rise of Oxygen:
- Before 2.3 billion years ago, the atmosphere was low in oxygen.
- We know this because of rocks called pyrite that have iron in them, and when iron is oxidized it rusts, & turns red.
- Photosynthesis brought the rise of oxygen
- Took 2 billion years before oxygen started to accumulate in the atmosphere
- But first had to oxidize all the unoxidized iron
- Early photosynthesizes include stromatolites that are 3.4 billion years old
Early Organisms on Earth:
Prokaryotes:
- Simple cell structure: Lacked Organelles & a nucleus
- Obtain energy from fermentation
- Low energy yield to organism
- Waste CO2 & alcohol
- Can't form 3-D
- Live singly or on end-to-end chains
- Uses oxygen from respiration
- Can form 3-D cells
- Have large cells with a nucleus & organelles
Evolution of Biosphere:
- Started to evolve because of the complexity of eukaryotes
- Changed the biochemical cycle on Earth
- Biosphere started to change
- Plants & animals began to evolve 700-500 million years ago
Life & Global Chemical Cells:
Micronutrients:
- Elements needed in small amounts by all life, some forms of life need a moderate amount
Macnutrients:
- 24 elements needed by all organisms
- "Big Six" - Building blocks of life
- Carbon, oxygen, hydrogen, nitrogen, phosphorus, & sulfur play a special role in an organism
- For life to continue elements need to be available with the right amount at the right time. Too much can be toxic, too little can limit growth, & some elements are neutral for life.
Biochemical Cycles:
To complete a path a chemical takes through 4 major components of Earths System which is:
- atmosphere, hydrosphere, lithosphere, & biosphere
General Aspects of Biochemical Cycles:
- Chemicals cycle quickly and are readily regenerated
- Other elements are immobile and is returned by geological processes
- Most required nutrient is light
- Evolution of live changed the biogeochemical cycles
- Can benefit the society but can also be a hazard
Simplest Way to View a Cycle: Box & Arrow Diagram
Boxes:
- Places where chemicals are stores
Source:
- Donating compartments
Sink:
- Receiving compartment
Residence Time:
- Amount of time atom spends in any compartment
Arrows:
- pathways of transfer
Flow:
- amount moving from one box to another
Flux:
- Rate/speed
Geological Cycle:
- Rocks and soil is continually created, maintained, changed and destroyed the last 4.6 billion years
- Changed due to physical, chemical and biological processes
Geologic Cycle- Group of Cycles:
- Tectonic
- Hydrologic
- Rock
- Biogeochemical
Tectonic Cycle:
- About 100 km thick and is broken in several plates
- Plate tectonics move 2 to 15 cm per year
- Location and Size of continent
- Change in climate
- Areas of volcanic activity/earthquakes
- Divergent: Plates move away from each other
- Convergent: Plates move into each other
- Two light plates creates a mountain
- Transform: Plate slides past another
Hydrologic Cycle:
- Transfer of water from oceans to the atmosphere to land and back to ocean
- Driven by solar energy
- Evaporation: Ocean
- Precipitation: Land
- 97% Ocean
- 2% Glaciers and Ice caps
- 0.001% in atmosphere
Rock Cycle:
- Has numerous processes that produce rock and soil
- Rocks: Igneous, Sedimentary, & Metamorphic
- Chemical weathering occurs when weak acids in water dissolve chemicals from rocks
Carbon Cycle:
- Carbon is element that anchors all organic substances
- Has a gaseous phase
- Carbon enters ocean by simple diffusion and then dissolve/transfer from land in rivers as dissolved carbon/wind
- Carbon enters biota (life) through photosynthesis and returned by fire or respiration
- Dead organism decomposes and released carbon, that are buried, & then turn into fossil fuels
Carbon Silicate Cycle:
- Cycling of carbon is intimately involved with cycling of silicon
- Carbonic acid falls as rain and weathers silicate rich rocks that later go into the ocean & used by marine animals to make shells
- Shells become part of the sedimentary rock layer and returns to surface in subduction zones
Nitrogen Cycle:
- Nitrogen is need for protein & DNA
- Makes up 78% of atmosphere
- Unreactive element and must be converted to NO3-(Nitrate) and NH4+ (Immonia) that's performed by bacteria
- Nitrogen fixation: process of converting atmospheric N to NO3- or NH4+
- Almost all organisms depend on N converting bacteria
- Industrial processing can now convert molecular N into compounds that can be used by the plants
- Nitrogen and Oxygen combine at high temps
- Oxide of Nitrogen is a source of air pollution
Phosphorus Cycle:
- Often a limiting factor for plants and algal growth
- No gaseous phase
- Low transfer rate
- Enters life through uptake by plants, algae and bacteria
- Goes back to soil when the plants die/ lost to oceans by runoff
- Birds return it to land