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Environmental Geology > Final Exam Study Guide > Flashcards

Final Exam Study Guide Flashcards

1
Q

Name the soil horizons in order

A

O, A, E, B, C, R

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2
Q

Which horizon contains the most organic material?

A

O horizon

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3
Q

What does the O horizon contain?

A

Organic material; specifically fresh and decaying plants

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4
Q

What does the A horizon contain?

A

surface soil (top soil); mostly mineral material, still rich in organic matter (humus), has high biological productivity

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5
Q

What does the E horizon contain and what is it?

A

Eluviated- zone of leaching;
-Contains soluble minerals leached, leaving primarily sand and silt sized silicates, often bleached
-found in older, well developed soils

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6
Q

What is the B horizon and what does it contain?

A

Subsoil-zone of accumulation
-depleted in organic matter, new organic materials precipitated from leaching

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7
Q

What is the C horizon and what does it contain?

A

Substratum
-contains parent material, weathered and broken bedrock or deposits (like glacial till, loess, mass movement debris)

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8
Q

What is the R horizon and what does it contain?

A

Bedrock
-contains unweathered rocks

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9
Q

What is the regolith?

A

soil area containing all horizons except the R horizon which contains bedrock
-does not count as soil bc it has no organic material

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10
Q

What is leaching?

A

loss of water soluble materials and nutrients from the upper portion of the soil profile
-dissolution of soluble minerals or material going into suspension

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11
Q

What is elluviation?

A

removal of dissolved or suspended material from a layer/s of soil when precipitation is greater than evaporation
-materials move downward in the soil due to gravity
-is leaching materials

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12
Q

What is illuviation?

A

introduction of minerals (salts) or nutrients into a soil horizon leached from a previous soil horizon

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13
Q

What is humification?

A

breakdown of organic matter

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14
Q

What is bioturbation?

A

disturbance and transport of sediment and pore water by organisms as they pass through soils they mix the soil and help oxygenate it

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15
Q

5 soil factors that control soil formation

A

CLORPT
-climate
-organisms
-relief
-parent material
-time

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16
Q

What is Cl in clorpt?

A

-climate-temp speeds up or slows down chemical reactions that break down/weather rocks and minerals in areas of high rainfall, more water drains down, leaching materials through the soil horizons

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17
Q

What is Or in clorpt?

A

organisms: burrowing animals, growing plant roots, and enzyme-secreting bacteria and fungi chemically alter and physically mix soil

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18
Q

What is R in clorpt?

A

-relief-slope and direction a landscape faces-influenced by sunlight hours, temperature, runoff, erosion and organic matter build-up

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19
Q

What is p in clorpt?

A

parent material: chemical composition of original unweathered rock influences the mineral content of the soil; parent materials can be underlying bedrock but most are sediments like sand, silt or clay carried elsewhere by wind or water

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20
Q

What is t in clorpt?

A

time: weathering partly depends on age: older soils are more weathered than younger ones; soils in the tropics tend to be old because they have not been affected by the remixing effects of glaciation

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21
Q

What is molarity?

A

concentration of a solution expressed in moles/L
Molarity=moles of solute/L of solution

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22
Q

What is molality?

A

a measure of solute concentration in a solution
m= moles of solute/kg of solvent

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23
Q

What is a reversible chemical reaction?

A

a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously

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24
Q

Are the rates in the two directions of the reversible chemical reaction the same or different when a reversible reaction is at equilibrium?

A

Law of mass action: the speed of the reaction is proportional to the concentration of the reactants; eventually you hit dynamic equilibrium when the speed of each reaction is the same

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25
Q

what is the solubility product?(define and give value)

A

a substance’s solubility, Ksp (a slightly soluble salt)
-an equilibrium constant that describes the degree to which a solid substance dissolves in an aqueous solution
-the more soluble a substance is, the higher the Ksp value will be

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26
Q

What is K?

A

the equilibrium constant

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27
Q

solubility reaction equation

A

K= concentration of products/concentrationof reactants
-In equilibrium studies, the value of the concentration of
a pure liquid or solid is defined as 1

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28
Q

what is the pH equation?

A

pH= -log (H+)

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29
Q

what is the pOH equation

A

pOH= -log (OH-)

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30
Q

How is pH related to the concentration of dissolved hydrogen?

A

pH value is the logarithmic value of the inverse of the hydrogen ion activity. Since the concentration of hydrogen ions is often low ion activity is considered as equal to the concentration of hydrogen ions

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31
Q

What is chemical activity?(definition and equation)

A

a=ym (a=chemical activity; y=activity coefficient; m=molal concentration)
-is a measure of the effective concentration of a species in a mixture, which takes into account the interactions between the molecules in the mixture
-used to calculate the chemical potential of an ideal solution
-dependent on temperature, pressure, and composition of the mixture

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32
Q

Under what conditions do we need to use chemical activity instead of concentration and why?

A

When electrostatic forces cause the behavior of the solutes to be nonideal

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33
Q

How do you calculate ionic strength in a mixture of electrolytes in solution?

A

I= 1/2 sum(miX zi)
I= ionic strength
mi= molality of the ith ion
zi= charge of the ith ion

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33
Q

What is ionic strength? (definition)

A

a quantity representing the strength of the electric field in a solution, equal to the sum of the molalities of each type of ion present multiplied by the square of their charges.

-concentration of ions in a solution
-ions dissociate when they are in water so electrolyte concentration affects important properties like the solubility of a salt

33
Q

How do you find the activity coefficient of an individual ion once ionic strength is known? What is it used for?

A

Debye-Huckel equation:
-log yi= Azi X square root of I/1+aiB X square root of I
-y= activity coefficient
zi=charge of the species i
I=ionic strength of the solution
A= temperature dependent constant
B=temperature dependent constant
ai= effective diameter of the ion
-used to account for deviation of mixture of chemical substances from ideal behavior

34
Q

What two equations can be used after finding the ionic strength? And when are they used?

A

Debye-Huckel and Davies equations
-Debye-Huckel: used for solution with an ionic strength of 0.1 or less

35
Q

What is the Davies equation and when do you use it?

A

-log yi= Azi^2 X square root of I/1+aiB X square root of I + 0.3 X square root of I
yi= activity coefficient of ionic species i
zi= charge of ionic species i
I=ionic strength of the solution
A=temperature dependent constant
B=temperature dependent constant
ai= effective diameter of the ion
-used for finding yi for solutions with a higher ionic strength (anything greater than 0.1)

36
Q

Why is there more than one equation for calculating the activity coefficient? What factor determines which equation is appropriate to use?

A

each are used depending on the ionic strength of a given solution
-ionic strength determines which to use

37
Q

What is Kiap?

A

Ion activity product
-used when total calcium, total carbonate, and ionic strength are known
-is calculated with the solubility product to determine whether the water is in equilibrium with calcite (saturation index)
-a measure of the activity of ions in a solution

38
Q

Kiap formula

A

Kiap/Ksp
-if greater than 1: solution is supersaturated
-if less than 1: solution is undersaturated
-if equal to 1: solution is in equilibrium

39
Q

What determines whether a substance will be toxic or non-toxic?

A

-all substances are potentially poisonous or toxic but it depends on the dose to determine if something is toxic or non toxic
-toxicity is expressed as an adverse effect

40
Q

Acute Exposure to toxicity

A

exposure at a relatively high dose over 14 days or less
-effects can range from mild to severe

41
Q

chronic exposure

A

exposure at a low dose over 365 days or more
-effects from chronic exposure may take years to develop

42
Q

intermediate exposure

A

exposure in between acute and chronic

43
Q

What is LDS 50?

A

the amount of a dose that kills 50% of the animals exposed to it, expressed in milligrams/kilogram body weight (LD= lethal dose)

44
Q

What is bioaccumulation?

A

the gradual accumulation of substances like pesticides or other chemicals in an organism
-occurs when an organism absorbs a substance faster than it can be lost
-PCB’s
-spreads up the food chain which increases the potential for greater concentrations of toxins the further up you go

45
Q

What are two factors that interact to determine risk in toxicity?

A

-species
-gender
-age
-nutrition
-genetics

46
Q

What does the earth being at thermal equilibrium mean?

A

solar radiation comes from the sun and heats the earth
-the amount of solar radiation coming in to the earth is balanced by the amount of long wave (IR) radiation going out

47
Q

What is a black body radiator?

A

an object which is a perfect absorber and emitter of radiation
-all wavelengths, any angle of incidence are absorbed
-total amount of energy emitted by the black body radiator is proportional to its temperature

48
Q

Why is the earth like a black body radiator?

A

-to stay in thermal equilibrium it must emit radiation at the same rate as it absorbs it so a black body radiator also radiates well

if the Earth is in thermal equilibrium, then Energy incoming= energy outgoing
-if we know the amount of energy reaching the earth, we can figure out what its (global average) temperature ought to be by treating it as a black body radiator
-like a black body radiator earth emitting and absorbing radiation proportional to its temperature

49
Q

With no CO2/greenhouse gas effect what would the average temperature of the Earth be like?

A

Earth would be 252 K and very cold. The earth would be a frozen, inhospitable place to live

50
Q

How do greenhouse gases work?

A

As Earth’s surface is heated by sunlight, it radiates part of this energy back toward space as infrared radiation. This radiation, unlike visible light, tends to be absorbed by the greenhouse gases in the atmosphere, raising its temperature. The heated atmosphere in turn radiates infrared radiation back toward Earth’s surface.

-greenhouse gases are transparent to visible light but highly absorbing for IR
-CO2, CH4, water vapor absorb and re-emit radiation which warms the earth
-gases exist in trace amounts in the atmosphere
-after earth is warmed by the sun, gases absorb the radiation coming from the earth as a result of the radiant heat and re-emit them to the earth which warms it up
-without these gases the earth would be freezing

51
Q

What is the Coriolis effect?

A

an effect whereby a mass moving in a rotating system experiences a force (the Coriolis force) acting perpendicular to the direction of motion and to the axis of rotation. On the earth, the effect tends to deflect moving objects to the right in the northern hemisphere and to the left in the southern and is important in the formation of cyclonic weather systems.

52
Q

What is positive feedback?

A

process in which the end products of an action are causing more of that action to occur in a feedback loop
-tends to lead to exponential growth or chaos

53
Q

What is negative feedback?

A

a response to positive feedback that reduces or reverses a positive feedback loop to its starting state

54
Q

What is a forcing?

A

-a forcing is something that comes from outside the system (or outside the dynamics of the system simply doing what they are doing) and pushes a system in a particular directions
eg-Milankovitch cycles – what is the shape of the orbit of the earth around the sun; tilt and shape of the earth is dependent on both seasons and positions of the earth in relationship to the sun. Shape of the earth’s orbit and the tilt both oscillate depending on fall and spring vs winter and summer=creates cyclical phenomenon which interact to form naturally occurring climate variation

55
Q

What are the 3 parameters that control the Milankovich cycle?

A

-eccentricity (orbital shape around the sun)
-obliquity (angle of tilt)
-Precession (wobble)

56
Q

What is eccentricity?

A

-eccentricity (orbital shape around the sun)- 100,000 years, 400,000 years
-small change in relative radiation
-caused by planets interacting with the earth

57
Q

What is obliquity?

A

-obliquity (angle of tilt)- 41,000 years -affects where solar radiation hits the earth; evenness of heating, affects intensity of seasons
-responsible for seasons
-affects on intensity of glacial episodes; high obliquity= deglaciation; low obliquity= glaciers where you have less intense winters and summers which means ice doesn’t get melted away as much during the summer

58
Q

What is precession?

A

-Precession (wobble)-19,000 years, 23,000 years- affects when seasons occur
-all three can interact with each other
-as the orbit becomes less circular, seasons length changes

59
Q

What makes eccentricity vary?

A

-gravitation pull of the other planets (Venus)
-the pull of another planet is strongest when the planets are close together
-the net result of all the mutual interactions between planets is to vary the eccentriticies of their orbits
-transgressions and regression= main driver of sea level cycles

Eccentricity Variations:
-cycles between two periods: 100,000 years and 400,000 years

-each orbital parameter cycles between different periods of time

60
Q

what are optimal conditions for glaciation?

A

-low obliquity (low seasonal contrast)
-high eccentricity and NH summers during aphelion (cold summers in the north)
**ice and snow are not completely melted during very cold summers
-most land is in the northern hemisphere (distribution of continents)

60
Q

What makes obliquity and precession vary?

A

-gravity
-the pull of the sun and the moon on earth’s equator
-tilting of the orbital plane

61
Q

what are optimal conditions for deglaciation?

A

Optimal Conditions for Deglaciation
-high obliquity and low eccentricity

62
Q

What are the types of ocean currents?

A

surface currents and thermohaline currents

63
Q

What are surface currents? What drives them?

A

wind driven movement of water at or near the surface
-majority of surface winds only move above the pycnocline
-friction between winds and surface water causes mass movement of water

64
Q

what is the pycnocline?

A

transitional layer between surface and deep water

65
Q

what is the thermocline? What drive thermocline circulation?

A

-a distinct layer based on temperature within a large body of water with a high gradient of distinct temperature differences associated with depth

temperature/salt- changes in salinity and temperature in different water bodies in different parts of the globe drive water movement; both temperature and salt affect the density of ocean water
-lower temperature up till a point (around 34 degrees) makes water more dense
-Colder= denser
-higher salinity= greater density
-evaporation increases the salinity
-precipitation=less salinity=less density
-thermohaline can be on the surface but are driven by densities below

66
Q

What the Ekman spiral?

A

-caused by the Coriolis effect
-the result of a force balance created by a shear stress force, Coriolis force and the water drag. This force balance gives a resulting current of the water different from the winds
-Friction with wind causes movement in the uppermost layer.
-The Coriolis Effect causes that moving water, if it’s moving North-South, to curve due to the conservation of momentum.
-That moving layer of surface water exerts
a frictional force on the next layer below it. But that frictional force is in the direction that that top layer of water is moving, at an angle from the direction (and force) of the wind.
-The second layer is pushed in the direction of movement of the first layer, but it also curves due to the Coriolis effect, because that layer has conserved it’s angular momentum.

67
Q

What is Ekman transport?

A

occurs when ocean surface waters are influenced by the friction force acting on them via the wind. As the wind blows it casts a friction force on the ocean surface that drags the upper 10-100m of the water column with it.[2] However, due to the influence of the Coriolis effect, the ocean water moves at a 90° angle from the direction of the surface wind.[2] The direction of transport is dependent on the hemisphere: in the northern hemisphere, transport occurs at 90° clockwise from wind direction, while in the southern hemisphere it occurs at 90° anticlockwise

68
Q

What is a gyre?

A

large-scale circular motion of currents around the periphery of an ocean basin
-there are 6: North Atlantic Gyre, the South Atlantic Gyre, the North Pacific Gyre, the South Pacific Gyre, the Indian Ocean Gyre, and the Antarctic Circumpolar Current

69
Q

How and why do eastern and western boundary currents tend to differ from one another?

A

Due to the offset ‘hill of water’, the
Western boundary currents are confined to a narrower space, and so must travel faster to move the same amount of water.

70
Q

what are western boundary currents?

A

-Sub-tropical western boundary currents are warm, deep, narrow, and fast-flowing currents that form on the west side of ocean basins due to western intensification
-They carry warm water from the tropics poleward

71
Q

what are eastern boundary currents?

A

relatively shallow, broad and slow-flowing
-found on the eastern side of oceanic basins
-Subtropical eastern boundary currents flow equatorward, transporting cold water from higher latitudes to lower latitudes
-Cold water associated with higher latitude oceans
-Coastal upwelling associated with
subtropical high pressure system

72
Q

How has CO2 and global average temperatures changed since the late 19th century?

A

-the amount of CO2 in the atmosphere has increased since the late 19th century as temperatures have also increased

73
Q

What is the difference between weather and climate?

A

-climate is the weather averaged over a long period of time (trends in the average)
-weather is the day-to-day variation
-World Meterological Organization often defines climate as a 30-year period, calculating the average of this and uses it as a baseline to look at temperatures before and after it

74
Q

What are some long-term (geological time scale) reservoirs of carbon?

A

-coal and petroleum, limestone (these three get released over long geological time scales), fossil fuels (less time than limestone/carbonate rocks)

75
Q

What are some short-term, ecological reservoirs for carbon?

A

forests, soils, wetlands, swamps, permafrost,

76
Q

what are stable isotopes?

A

non-radioactive forms of atoms that can be used by measuring their amounts and proportions in water samples
-naturally ocurring isotopes are used to trace origin, history, sources, sinks and interactions in water, carbon and nitrogen cycles

77
Q

How are stable oxygen isotopes useful in understanding the ancient climate?

A

-ice cores provide a (nearly) direct record of CO2 prior to direct measurements
-temperature data from the isotopes like O-18/0-16
-look at bubbling from gases
-look at concentration of carbonic acid dissolved in the ice which depends on partial pressure from CO2 in the atmosphere
-can get them from the last 640,000 years
-from them we see that when CO2 increases temperature always follows
-tree rings: can look at carbon isotopes, can also get partial pressure of CO2 in the atmosphere
-trees grow faster in warmer climates and give details on seasonal cycles
-the further you go back in time (more than 640,000 years) is harder: the oldest ice is less than a million years old. Other places to look: seashells made of CaCO3; seawater makeup to seashell material is fairly constant which allows you take a seashell isotopic value as a proxy for seawater isotopic values. If there is a shift in isotopic values of oxygen then there was likely a shift in sea trends. These can be used as a paleothermometer.
-external forcing (the driver in changes in earth’s orbit) drives changes in CO2
-heavier isotopes is more inclined to go into ice; icebergs will have slightly more o18 than o16 because o18 will be more inclined to go into the iceberg whereas o16 will be inclined to stay in the liquid water
-ice will be slightly isotopically heavier whereas water will be isotopically lighter
-land ice on top of a mountain: lighter oxygen isotope will be slightly more inclined to evaporate than the heavier isotope
-growing ice will change the isotopic ratio of the change which changes the isotopic ratio of land and other places with ice
-changing the isotopic composition of the ocean changes shell composition (like foraminiferans, CaCO3)
-climatic processes drive isotopic composition
-modeling approaches to see CO2 concentrations can tell us about CO2 over hundreds of millions of years
-to proxy the past you model how the trends vary based on global ocean anoxia and global atmospheric ratio and compare it to oxygen, sulfur, and carbon isotopic data

78
Q

What are two additional greenhouse gases besides CO2?

A

CH4 and N2O

79
Q

What evidence do we have for humans burning of fossil fuels causing the CO2 increase?

A

-fossil fuel CO2 emissions show rapid global CO2 emissions post WW2 which can be broken down according to where their coming from
-some is coming from fossil fuel
-land use (deforestation)
-other – mostly cement)
-CH4 14%
-Remainder N2O etc 9%
-different carbon sources have different carbon isotopic values (different carbon-13 to carbon-12 isotopic ratios)
-one way to see concentration of what is in the atmosphere is to compare isotopic values to get which carbon sources are the greatest contributors of CO2 in the atmosphere

80
Q

What is upwelling?

A

In coastal areas where winds blow along the coast, net water movement moves away from the shore and causes deep water to move towards the shore causing upwelling, moving nutrients to the surface making regions of high productivity

81
Q

What is downwelling?

A

wind moving south to north pushes water towards the coast is forced down creating downwelling which makes nutrient poor surface areas and less productive areas
-sinking of higher density material under warmer water

Environmental Geology (4 decks)

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