Geology

sunlight

primary source of energy input to the earths surface

greenhouse effect

longer wavelength infrared rays of radiated heat are less able than the original sunlight to pass through the gases

CO2

ocean/atmospheric exchange, decomposition, volcanic emissions

N2O

microbial processes in soils, ocean/atmosphere exchange, chemical reactions in the upper atmosphere

CH4

microbial processes in swamps/wetlands, oceans/methane hydrates, termites

O3

chemical reactions in the upper atmosphere

H2O

evaporation of (ocean) water

CO2

fossil fuel use, deforestation (trees are burned/decay, loss of trees to use CO2)

N20

agriculture (fertilizers), fossil fuels, sewage

CH4

fossil fuel production, livestock, rice agriculture, landfills, biomass burning

O3

NOx and VOC compounds from industry react with sunlight to form O3

H2O

global warming from other gases increases evaporation

natural but humans are a fast new source

Do humans or natural causes contribute more to the contribution of CO2?

electricity and heat

largest human use of fossil fuels that contribute to CO2 emissions

CO2

as temperature increases what is released through the ocean

CO2 concentrations

global temperature correlate with what due to Milankovitch cycles?

fossil fuel combustion

largest human activities that contribute to CO2 emissions

snowball earth theory

neoproterozoic glacial deposits are found throughout the world, even in places that were near the equator during this time (based on paleomagnetism)

some scientists say the entire planet was encrusted with ice

proterozoic

when did snowball earth occur

major evidence of snowball earth

\-glacial tillites

\-dropstones by equator

\-signature of ice sheet movement

global ice ages

relative concentrations of major atmospheric gases contribute to?

ice albedo

ice reflects more sunlight energy

end of snow ball earth

limited weathering on a snowball earth led to the buildup of atmospheric CO2

permo triassic extinction

the largest mass extinction (80%-96%)

casualties

* all trilobites, tabulate and rugose corals, major groups of brachiopods
* only 2 genera of ammonites survived
* duration (10,000 to 165000)
* total ecosystem collapse

causes of the Permo-Triassic Extinction event

* two events of widespread ocean anoxia, seas become stagnant
* anoxia because global warming prevented cold, 02 rich water from sinking at the poled (interrupted the oceanic circulation system)
* gray chert replaced oxidized hematite in ocean sediments as oxygen was depleted
* accompanied by a strong negative shift in carbon 13 for sediments
* meteorite impacts during time may have contributed to the extinction event

siberian traps

erupted through the worlds largest deposit of carboniferous coal, causing the release of massive amounts of additional CO2 and methane

Methane Hydrates

Clathrates found in oceanic sediment at water depths greater than 300m where the bottom water temperature is around 2 C

* isotopically light carbon
* causes permian triassic extinction is massive release of light carbon in the form of methane

desert

a barren area of land where little precipitation occurs, and conditions are hostile for plant and animal life. Deserts support little vegetation, are usually arid ( or ice covered) and can be hot or cold

desertification

term that usually is applied to rapid human-induced causes for the expansion of deserts in areas that formerly were vegetated

hadley cells

global air circulation

* global atmospheric circulation cells cause high pressure zones where they descend and low pressure where air is rising
* warm air holds more moisture than cold air
* air under pressure can hold more moisture
* air masses moving up into cooler altitudes of the atmosphere lose more moisture in the form of precipitation

rain shadow effect

* occur when moist air form the ocean flows over mountains, forcing it up into cooler altitudes
* as air cools the moisture is lost as rain or snow
* on the downside of the mountain, the now dry air becomes warmer as it descends, causing further evaporation of moisture and creating a desert

abrasion

wearing away a solid object by the impact of particles carried by the wind. (sandblasting effect)

deflation

removal of loose sediment by the wind. Usually removes the fine-grained fraction of the sediment

desert pavement

a layer of pebbles or rock fragments that forms on the surface of a desert soil, where wind has “winnowed” or removed the finer grained material

dunes

low angled mound of ridge of sediment (usually sand) that forms during transport by wind

dune migration

sediment grains are transported up the less steep windward side and spill over the slip face ( the steeper downward side)

cross bedding

dune migration causes?

loess

windblown silt, very fine-grained sediment (.01-.06 mm) it can be carried much further and more easily than sand, suspended in the wind for many kilometers.

characteristics of loess

* fine rock powder created by glaciers as they ground the underlying rocks
* blown by wind
* lots of soluble minerals that provide nutrient elements for plants, making it very good agricultural soil also retains moisture well for plants

largest reservoirs of water

oceans, ice, ground water, lakes and streams, atmosphere, biosphere

largest reservoirs of fresh water

ice, ground water, lakes and streams

hydrosphere

all water at or near the surface of the earth

fluxes

evaporation, precipitation, overland flow, infiltration, sublimation, and transpiration

porosity

proportion of void space in a rock, sediment, or soil

permeability

the degree to which the pores or cracks are interconnected allowing fluids to migrate through the material

lower porosity

greater degree of cementation

greater porosity

larger grain sediment

greater porosity

uniform grain size

aquifer

a rock unit that holds enough water and transmits it rapidly enough to be useful as a source of water. ( has sufficient porosity and permeability) SANDSTONE

aquitard

a rock unit that does not transmit water readily (has low porosity and or permeability) SHALES

phreatic zone

zone of aeration- rock or soil above the phreatic zone in which the pore spaces are partially filled with water and partially with air (unsaturated)

water table

the surface of the phreatic zone, assuming that the aquifer is not confined (overlain by an aquitard layer)

recharge

processes of infiltration and migration by which ground water is replenished to the aquifer. Ground water can flow laterally or infiltrate from above.

vadose zone

unsaturated zone

hydraulic head

elevation to which water will rise above the screened section of a well at a given point in an aquifer. It represents the total potential mechanical energy of the water. Used to calculate hydraulic gradient between two points.

hydraulic gradient

used in calculations to determine rates of ground water flow. Represents the slope of the water table between two points

ground water flows from areas of higher to lower hydraulic gradient

potentiometric surface

the height to which waters pressure would raise the water if it were unconfined, or the level to which it would rise in a well drilled into an aquifer. For a confined aquifer it is usually some height above the top of the confined phreatic zone, for an unconfined aquifer it is equal to the water table.

confined aquifer

the phreatic zone is bounded above and below by low permeability rocks (aquitards) which prevent free flow of water

artesian well

a well drilled in a confined aquifer where water pressure in the aquifer is sufficient to cause water to rise on its own (without pumping) up a well that is drilled into the aquifer. Water may rise completely to the ground surface or just part way up the well.

groundwater flow rates

most aquifers are usually on the order of only meters or tens of meters per year

groundwater mining

removing water at a rate faster than it will be replaced on a human time scale

land subsidence

consequence of extraction of groundwater that has no recharge

saltwater intrusion

fresh water lens is depleted faster than its rate of recharge, causing salt water to be pulled inland and up to fill the empty pore space with pumping

in coastal areas the fresh water in an aquifer may be a lens of fresh water floating atop more dense salt water that infiltrates from the ocean

recharge well

water can be pumped into a recharge well near the fresh water/ salt water interface to increase hydraulic head there and prevent salt water from flowing toward the zone of groundwater pumping

urbanization

increases the amount of impermeable ground cover, (buildings, pavement, etc) will reduce the rate of infiltration and recharge

recharge basins

artificial ponds may be used to retain surface runoff and allow water to slowly infiltrate to recharge the aquifer

also used to flood control purposes

sinkhole

* limestone or evaporite (salt or gypsum) formations are particularly soluble in water
* groundwater flowing through fractures may dissolve away soluble rock and erode large caverns or caves
* groundwater may actually occur as an underground stream or lake within the cave systems

karsts

regions underlain by salt or gypsum that are susceptible to sinkhole formation

hydroelectric generation

biggest user off water but not biggest consumer because most water used for this purpose gets returned to the hydrosphere

irrigation

biggest consumer of liquid freshwater supplies, most water used for irrigation is lost to crops and evaporation

conservation

use less water for the same activities

* more efficient drip irrigation methods (biggest potential for savings)
* more efficient appliances and industrial techniques/equipment

interbasin water transfer

divert water from where it is available but not needed to places where it is needed, often over great distances.

* often used to supply water for big cities including NY but most especially in arid regions like LA and other parts of the western US

problems with interbasin water transfer

* inefficient ( lots of evaporative loss during transport in large aqueducts)
* negative environmental effects in source area (drying up of lakes)
* lots of legal and political issues and disputes, especially as water becomes more scarce

desalination

turn salt water from ocean into fresh water

* filtration/osmosis is relatively cheap but can only process limited amounts of water, not efficient

problems with desalination

* distillation involves evaporating salt water and condensing the vapor to collect fresh water
* uses fossil fuels or solar energy
* energy intensive and expensive
* would be very expensive to use for agricultural irrigation water will cost 5-15 times more than using natural fresh water supplies