A. Biogeochemical cycles- bio=life, geo=earth,
chemical=compounds “biologically important”. Cellular life, as we
understand it, could not exist without certain elemental components. Hence,
some elements are deemed "biologically necessary
for life" and in this sense are considered more important than other
elements of the periodic table.
| 1. Carbon cycle | -source of atmospheric CO2= combustion and cellular
respiration
-sink of C (where it settles)= forest trees and oceans where C is held in the biomass of wood or algae. Life is carbon-based; our cell structure contains many carbon chains. - IS the impact from fossil fuel combustion leading to global warming??? |
| 2. Nitrogen cycle |
-amino acids, peptides, and proteins are needed by ALL organisms to exist; these organic compounds all require N in the NH2 amino groups -N is the most abundant gas in the atmosphere. However in the N2 stable form plants cannot use it. It must be converted into a useable nitrate form, by bacteria, in order to be absorbed by plant roots. -Why is N so important to plants? It is part of the central core molecule of the light harvesting pigment chlorophyll of plants and algae. Without, N and Mg for chlorophyll, there would be almost no photosynthesis, meaning no food for consumer organisms, meaning a reduced food chain- so most life would DIE OFF!!!! -However, since the increase in automobile use, NOx has played a significant role in photochemical smog production, and is linked to global thermal increases, especially in cities. |
| 3. Phosphorous cycle | -P is important to all plants and animals because of its involvement
in E transfer reactions and also because of its stabilizing role in the
structure of DNA!
-The phosphorous cycle includes only terresterial and aquatic conditions-NO atmospheric involvement. -In water, excess phosphates cause algal blooms in aquatic conditions. This is a fast growth form of algae which occurs so quickly that nutrients in the water are quickly absorbed and then the resulting huge algae population dies quickly in the water. Upon death, it begins to rot and ALL of the oxygen in the water is consumed by bacteria rotting the biomass so that little oxygen is left in the water for fish or other larger forms of life. The larger forms of life then DIE OFF!!! |
| 4. Sulfur Cycle | - Important for organisms for protein stability; it forms crosslinks
in proteins to stabilize their large 3D structures. Since ALL life
has protiens, then S is important.
-Most of earth’s sulfur lies in mineral beds and deposits; it is released by microorganisms and primarily by mining from man, nowadays. |
| 5. Water cycle | Solar energy drives the water cycle by evaporating
surface water. Evaporation is liquid changing form into a
gas; sublimination is liquid changing from solid into a gas (freeze
drying). Either way, liquid enters the atmosphere as vapor particles,
causing humidity. The atmosphere can only hold so much water
at a temperature, and when this amount is reached, the atmosphere has reached
the saturation point. Relative humidity is the amount of water
held in the air compared to the amount possible at a given temperature.
Water droplets fall back to earth as precipitation when the water vapor condenses, aggregates bond together, on particles rising up into the atmosphere. These particles are known as condensation nuclei, and may consist of smoke, dust, salts, ash... Some water vapor molecules bond onto a molecule, adding weight to it. Then, because water is cohesive- able to bond to other like molecules- more water molecules bond to these forming droplets with the particle inside. Eventually the molecule becomes heavy enough and falls to the earth as precipitation. Ground water is FRESH water that is stored in the ground. Most of earth’s water, 97%, is salt water unfit for human consumption- it wreaks havoc on your renal system/ kidneys. The remaining 2.5% is fresh water in solid, glacier form, or liquid form in lakes and aquifers. Aquifers are underground lakes which do not drain because they are surrounded by rock layers. Ground water flows across the surface and percolates into the soil layers. The upper soil layer holds roots, a zone of aeration. Water can be absorbed by roots or sink lower into the zone of saturation and lower into the ground water table- the top level of continuous water in the ground. Wells are sunk to this level. If a well has pressure exerted on it from water at a higher level in the soil, then the water will flow freely up out of the well without a pump- an artesian well. Areas in which water seeps into an aquifer are known as recharge zones- the ground surface from which the aquifer recharges. A watershed is all the land, hills, valleys which drain into a river. River flow can be measured by discharge- how much water passes a fixed point in an amount of time. |
| 6. Seasons on Earth | The tilt of the Earth at 23.5o
on its rotational axis has an effect of dispersing parallel rays of sunlight
across different amounts of land surface areas, depending on the position
of the earth in its orbit in relation to the sun.
ie. solstice designations (June & Dec.) refer to our hemisphere tilt towards or away from the sun ie. while equinox dates (March & Sept.) mark the half-way period between solstices AND the fact that earth’s position in its orbit is positioned where both hemispheres receive equal amounts of daylight and darkness. |
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7. Layers of the Atmosphere |
a. biosphere/troposphere- 1 mi./ 6 mi
- life & weather occur here
b. stratosphere- 6 - 30 mi.- constant wind, no turbulance; OZONE Layer for UV protection found here; CFCs damaged the ozone layer. c. mesosphere 30- 50 mi, severe temp. decreases d. thermosphere- 50- 300 mi.; severe temp increase due to UV radiation presence; atmosphere begins to thin out and become "deep space". |
| a. Convection | From a rapidly heated ground surface, thermal currents of warm air rise up into the atmosphere. As this happens dust/ condensation nuclei are brought up into the atmosphere and the water droplets collect and form on the dust. The droplets grow heavy and fall back to earth. Generally, this process happens quickly and is responsible for severs cloudbursts and afternoon thunderstorms. |
| b. Frontal | Cold air masses are heavier, denser masses than warm, moist air. As a cold front moves into a region, it travels along low in the atmosphere hugging the surface. As the cold front moves into a warm air mass, which is less dense, it bumps the warm air up on top of it. The zone where the cold air and warm air meet is unstable due to changing cooling temperatures which cause water condensation and droplet formation. This type of condensation is responsible for prolonged rainy days. The warm air mass sits atop the cool mass and its temperature drops slowly. |
| c. Orographic | As wind travels up the windward side of a mountain (usually the western side), it pulls with it dust nuclei and water vapor. As elevation increases, temperature and pressure decrease and relative humidity increases (high UV exposure & more evaporation). As the droplets coalesce due to cool temperatures climbing up the mountainside, the droplets become heavy and fall out of the atmosphere on the same side of the mountain. As the dry atmosphere passes the mountaintop and down the other side of the mountain, leeward, no precipitation is left to deposit. Hence, one side of a mountain is usually dry and barren. |
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9. Earth Structure & Tectonics |
Inner core of solid metals, mostly Fe, thousands of km in diameter, surrounded molten, liquid metals of outer core. Surrounding this is a layer of pliable rock and lighter elements of Si, O, Mg, the mantle. The outermost layer is the crust of rock that floats on the mantle. It is shallow on the ocean floor (10 km thick) and thicker on the continents. The crust is broken into floating discs or tectonic plates of continents and land masses- about 14 major plates. The plates shift, jerk, and slide past each other. Where plate edges collide, upthrust forms mountain ranges forcing rock upwards, along with molten rock, magma; subduction causes a plate edge to be forced under a dominant, larger plate. The rock is pushed into the mantle and melted. |
| 10. Geologic Hazards | a. Earthquakes are releases of pressure along weak points,
faults, of colliding tectonic plates. The plates force against each
other, hold steady for awhile, building pressure, and then when the pressure
becomes too great, they SNAP past each other, and the ground (whole plate)
jumps in a direction causing the earthquake. When earthquakes happen
in the ocean floor, a HUGE seismic ripple wave shoots out from that spot,
and races through the water with momentum; HUGE = possible 200’ tall and
400-600 mph!!!
b. Volcanoes are the release of molten thermal pressure building within earth’s core through ground or sea floor vents. The pressure which builds is so great that molten rock, lava, solid rock, gas clouds, and poisons may rupture out of the earth. Destructive, speedy, thermal poisonous gas clouds and ash are known as PYROCLASTIC eruptions and may be as hot as 1000-2000o C and travel as fast as 100 mph and incinerate everything in its path! This is what happened at Pompeii, and more recently, in 1996 in South America. |