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USEFUL FACTS CONCERNING THE EARTH
‘^’ means ‘to the power of’
pi - 3.14159; e = 2.718228; Surface area of a sphere - 4piR^2
1 gram = 10^-3 kg; = 10^-6 megagrams (tonnes); 10^-9 gigagrams; = 10^-12 teragrams (Tgrams); = (femto);= (atto).
1 gram = 10^3 milligrams; = 10^6 micrograms; = 10^9 nanograms; = 10^12 picograms
1 kg = 10^3 grams; = 10^-3 tons; = 10^-9 Tgrams
1 kg = 10^6 milligrams = 10^9 micrograms = 10^12 nanograms = 10^15 picograms
1 litre = 10^3 millilitres (ccs) = 10x10x10 decametres = 10^-12 km^3 (1 km^3 = 10^12 litres)
1 short ton =.907184 tonnes; 1 long ton = 1.0160469 tonnes
1 ppm = 1 kg / 10^6 kg or 1 gram / 10^6 grams, etc.; = 1 mgram/kg.
Atomic mass, major elements: Si - 28.09; Ti - 47.88; Al - 26.98; Fe - 55.85; Mg - 24.31;
Ca - 40.08; Na - 22.99; K - 39.1; P - 30.97; oxygen - 16; Cl - 35.45; carbon - 12.01; S -
32.07
Concentration - micromoles/litre = 10^-6 moles/litre = 10^-9 moles/millilitre
(Mass concentration = Atomic mass x micromoles/litre x 10^-9 kg/kg;
e.g. Ca, 558000 x 35.45 x 10^-9 = 0.0198 kg/kg)
Concentration - millimoles/litre = 10^-3 moles/litre = 10^-6 moles per millilitre
(Mass concentration, e.g. Mg, = 54 x 24 x 10^-6 = .00129 kg/kg)
Equatorial radius 6,378.137 km
Polar radius 6,356.752 km
Equivolume sphere radius 6,371 km (4 pi R^2)
Surface area 5.1 x 10^8 km^2
Circumference 40,030 km (2 pi R)
Mass, M 5.97369 x 10^24 kg
Mean Density 5.5148 x 10^3 kg / m^3
Density of continental crust 2.7500 x 10^3 kg / m^3
Gravity at equator 9.7803267 m / s^2
Gravity at poles 9.832186 m / s^2
Mean land elevation 825 m
Mean ocean dept 3,770 m
Depth of ridge crests below sea level 2,500 m
Area of oceans excluding continental margins 3. 1 x 10^8 km^2
Land area of continental crust 1.48 x 10^8 km^2
Continental crust plus continental margins 2 x 10^8 km^2
Average thickness of continental crust 38 km
Average thickness of oceanic crust 6 km
Volume of continental crust 7.6 x 10^9 km^3
Volume of continental sediments on ocean floors 1.6 x 10^8 km^3
Age of the Earth 4.5 Ma
Total length of active ocean ridges 56,000 km
Average rate of prod, oceanic crust (Mes. - Cen.) 25 km^3 /yr
Present day production of oceanic crust 17 km^3 /yr
Ave product / km of ridge length (Mes. - Cen.) 450 km^3 /km /Ma
Total length of destructive margins 37,000 km
Average velocity of subduction 80 km /Ma
Ave subduction rate / km of margin (Mes. - Cen.) 675 km^3 /km /Ma
Average area of the oceans is 3.6 x 10^8 km^2 = c. 71% of the surface of the Earth.
Volume of rain water entering the oceans from rivers 4 x 10^16 kg = 4 x 10^4 km^3
Calculated surface of oceans at 71% of 5.1 x 10^8: 3.62 x 10^8 km^2
Calculated volume of the oceans if depth is 3.73 1.354 x 10^9 km3
Calculated surface of the continents at 29%: 1.479 x 10^8
The following data may be consulted in:
Berner, E.K. and Berner, R.A., 1987 The Global Water Cycle. Prentice
Hall, N.J., 397p.
Berner, E.K. and Berner, R.A., 1996 Global Environment. Prentice
Hall, 376p.
Open University Course Team, 1992 Seawater. its composition,
properties and behaviour. Open University and Pergamon Press.
Open University Course Team, 1989 The Ocean Basins. their structure
and evolution. Open University and Pergamon Press, 171 p.
Open University course team, 1989 Ocean Chemistry and Deep-sea
sediments. Open University and Pergamon Press, 134 p.
Pinet, M. 1996. Oceanography.
Water Reservoirs 10^6 km^3
Oceans 1370 97.25
Ice masses 29 2.05
Groundwater 9.5 0.68
Lakes 0.125 0.01
Atmosphere 0.013 0.001
Rivers 0.0017 0.0001
Biosphere 0.0006 0.00004
Precip on land 110300
Evap from land 72900
Water entering rivers 37400 (4 x 10^4 km^3/yr)
Precip on oceans 385700
Evap from oceans 423100
Total precip 496000
Total evap 496000
Salt
Surface area of the Earth = 4piR2 = (4 x 3.1416 x (6378)^2) km^2 = 5.1119 x 10^8 km^2
Continental area = 4piR2 x 0.29 = (4 x 3.1416 x (6378)^2) km^2 x 0.29 = 1.4824 x 10^8 km^2
Ocean area = 4piR2 x 0.71 = (4 x 3.1416 x (6378)^2) km^2 x 0.71 = 3.6294 x 10^8 km^2
Ratio of oceanic area to continental area = 2.4483
1 m = 100 cm; 1 km = 1000 m;
1 l = 1000 cm^3 = 1 dm^3 1 km^3 = 109 m^3 = 10^12 dm^3 (litres) = 10^12 kg (SG = 1)
Ocean volume = 4piR2 x depth x %ocean surface = 4 x 3.1416 x (6378)2 x 3.73 x 0.71
= 1.354x10^9 km^3. (S x 4 x 0.71 km^3 = S x 2.8 km^3)
SG of seawater is 1.0265 at 5oC and salinity of 35, and therefore mass of sea water =
1.354x 10^9 x 1.0265 x 10^12 kg = 1.39 x 10^9 x 10^12 kg
(S x 4 x 0.71 x 1 x 10^12 kg = S x 2.8 x 10^12)
Salt (all principal ions) content of sea water is .035 kg/kg of seawater)
therefore total mass of salt is .035 x 1.39^24 x 10^21 kg = 4.86 x 10^19 kg
(S x 4 x 0.71 x 1 x 10^12 x .035 kg = S x 0.1 x 10^12)
and since SG of salt is c. 2.17
the total volume of salt = 4.74 x 10^19 x 1 x 10^-12 / 2.17 = 2.224 x 10^7 km^3
(S x 4 x 0.71 x 1 x .035 / 2 km^3 = S x 0.05 x 10^12)
If all the salt in the oceans were spread over only the continents, its thickness would be:
(2.224 x 107) / (1.4824 x 108) km = 151 m.
Calculated another way using approximations, where S is the surface area of the Earth,
the salt thickness would be:
(Surface area of the Earth x oceanic prop x depth of oceans x salt conc. x SG of sea
water x SG salt) / (Surface area of the Earth x continent proportion) = (S x 0.71 x 4 x 1
x 0.035 / 2) / (S x 0.29) km = 0.05 / 0.3 = c. 0.165 km = 165 metres.
The calculated thickness is similar to the estimate of 500 feet (170 m) of Swensen
(If the salt in the sea could be removed and spread evenly over the Earth's land surface it
would form a layer more than 500 feet thick, .. salty.ref)
If the salt were spread over the whole of the Earth, its thickness would be :
(2.184 x 107 / 5.10101 x 108 x 1000) metres = 44 metres
The thickness in the oceans only would be (2.184 x 107 km^3 / 3.63 x 108 x 1000) metres = 61 metres
Lithsphere is 250 km thick under the continents.
Lithosphere is 100 km thick under the oceans.
Maximum height - 8.5 km
Average height = 0.8 km
Averge depth of sea - 3.7 km
Maximum depth - 11.04
21% of earth's surface lies between sea level and 1 km
23.2% lies between 4 - 5 km depth
Pacific Atlantic Indian World Medit.
Oceanic area 10^6, 180 107 74 361 2.5
Land area drained 10^6 19 69 13 101
Ocean/drainage area 9.5 1.6 5.7 3.6
Average depth, km 3.94 3.31 3.84 3.73 1.5
Ave volume 1.346x10^9 km^3
= 1.345x10^21 litres
Ave mass (Vol x 1.0265) 1.382x10^21 kg
Area as % of total:
Mid-ocean ridges, % 35.9 31.2 30.2 32.7
Trenches, % 2.9 .7 .3 1.7
Shelf and slope, % 13.1 19.4 9.1 15.3
Rise, % 2.7 8.5 5.7 5.3
Abyssal deeps, % 42.9 38.1 49.3 41.9
Volcanic edifices, % 2.5 2.1 5.4 3.1
Meditteranean
Surface area - 2.5 10^ km^2
Average depth 1.5 km
Volume 3.75 x 10^6 km^3
Amount of salt = 3.75 x 10^6 x 10^12 x .035 = 1.3 x 10^17 kg
Area of the floor of the Meditteranean - 2 x 10^6 km^2
Equivalent thicknes of salt - 32.8 m
Thickness of salt in the Miocene Messinian deposits - 1 km
Loss of water from the Mediterranean by evaporation - 4.7 x 10^3 km^3
Precipitation in the Medit. - 1.2 x 10^3 km^3
Rivers contribute to the Med - 0.25x10^3 km^3
Net loss through precipitation - 3.25 x 10^3 km^3, made up by addition of Atlantic water.
Time to dry up if no replacement = 1.15 x 10^3 years
Hydrothermal vent solution at c. 350 deg.C at 21N on the East Pacific Rise, ppm by weight;
pH of the vent solution is 4.0 whereas normal seawater is about 8.
If 1.7 x 10^14 kg of seawater circulates through th oceanic crust each year and if it picks
up 460 ppm (460 ppm = 4.60 x 10^-4 kg / kg) then 7.8 x 10^10 kg of Ca is added to the
seas, compared with 5 x 10^11 kg introduced from rivers.
vent seawater
,ppm ,ppm
Cl 17300 = 0.0173 kg/kg 19500 = 0.0195 kg/kg
Na 9931 = 0.0099 kg/kg 10500 = 0.0105 kg/kg
Mg - 1290 = 0.00129 kg/kg
SO42- - 905
H2S 210 -
Ca 860 400
K 975 380
Sr 8 8
Si 600 3
Ba 5-13 2x10^-2
Zn 7 5x10^-3
Mn 33 1x10^-4
Fe 101 2x10^-4
Sediments Atlantic Pacific Indian World
Calcareous ooze 65.1 36.2 54.3 47.1
Pteropod ooze 2.4 0.1 - 0.6
Diatom ooze 6.7 10.1 19.9 11.6
Radiolarian ooze - 4.6 .5 2.6
Pelagic clay 25.8 49.0 25.3 38.1
Rel % size of ocean 23 53.4 23.6 100
Ratio of illite to quartz = 4, except South Pacific = 7
Illite: N Atlantic 60; S. Atlantic 50; North Pacific 40; Indian 35; S. Pacific 28
Concentration Total Amount
in the oceans in the oceans
ppm tonnes (1 tonne = 10^3 kg)
Cl 1.95x10^4 2.57x10^16 Cl-
Cl 0.0195 kg/kg 2.57x10^19 kg
Na 1.077x10^4 1.42x10^16 Na+
Mg 0.129 " 0.71 " Mg2+
Ca 0.0412 " 0.0545 " Ca2+
K 0.038 " 0.0502 " K+
S 0.0905 " 0.12 " SO42- (= 2.7 ppm)
Br 67 8.86x10^13 Br-
Br 67x10^-6 kg/kg 8.86x10^16 kg
C 28 3.7 HCO3-, CO32-, CO2
N 11.5 1.5 N2, NO3-, NH4+
Sr 8 1.06
O 6 7.93x10^12
B 4.4 5.82
Si 2 2.64
P 6x10^-2 7.93x10^10 HPO42-, PO43-, H2PO4-
P 6x10^-8 kg/kg 7.93x10^13
Ti 1x10^-3 1.32x10^9 Ti(OH)4
Al 4x10^-4 5.29x10^8 Al(OH)4-
Al 4x10^-10 kg/kg 5.29x10^11 kg
Mn 1 1.32 Mn2+, MnCl+
Cu 1 1.32
Fe 5.5x10^-5 7.26x10^7
Zr 3 3.97
Nb 1 1.32
Be 5.6 x10^-6 7.4 x10^6
Au 4 " 5.29 AuCl2-
La 3 " 3.97 La(OH)3
Nd 3 " 3.97
Pb 2 " 2.64
Ce 1 " 1.32
Y 1.3 " 1.73
Yb 8x10^-7 1.06
Sm 5x10^-8 6.61x10^4
Eu 1 1.32
Ave % of 10 most abundant elements in the Earths crust, wt %, compared with
seawater, kg/kg or kg/litre):
Element Crust In seawater % in solution
Si 28.2
Al 8.2
Fe 5.6
Ca 4.2 0.000412 kg/kg 1.7
Na 2.4 0.01076 74.7%
K 2.1 0.000387 3.1
Mg 2.3 0.001294
Ti 0.6
Mn 0.1
P 0.1
Dissolved substance in river water, ppm
Bicarbonate 58.8 5.88 x10^-5 kg/kg 48.7%
Ca2+ 15 1.50 x10^-5 kg/kg 12.4
SiO2 13.1 1.31 x10^-5 kg/kg 10.8
SO42- 1.2 1.20 x10^-6 kg/kg 9.3
Cl 7.8 7.80 x10^-6 kg/kg 6.5
Na+ 6.3 6.30 x10^-6 kg/kg 5.2
Mg2+ 4.1 4.10 x10^-6 kg/kg 3.4
K+ 2.3 2.30 x10^-6 kg/kg 1.9
NO3- 1.0 1.00 x10^-6 kg/kg 0.8
(Fe,Al)2O3 0.9 9.00 x10^-7 kg/kg 0.8
Remainder 0.3 3.00 x10^-7 kg/kg 0.3
Photic zone rarely extend below 200m of the ocean
3/4 of organic matter in sinking particles that leave the photic zone are decomposed and
recycled in the upper 500-1000 m of the water column.
At the compensation depth the oxygen produced by phytoplankton during
photosynthesis equals the amount they consume in respiration over a 24 hour period.
Concentration - micromoles/litre = 10^-6 moles/litre = 10^-9 moles/millilitre
(Mass concentration = Atomic mass x micromoles/litre x 10^-9 kg/kg;
e.g. 558000 x 35.45 x 10^-9 = 0.0198 kg/kg)
Component River Seawater Tau(r) (1000 yr)
Water
Cl- 230 558,000 (=0.0198 kg/kg) 87,000
Na- 315 479,000 55,000
Mg-- 150 54,300 13,000
S04-- 120 28,900 8,700
Ca++ 367 10,500 1,000
K+ 36 10,400 10,000
HCO3- 870 2,000 83
H4SIO4 170 100 21
NO-3 10 20 72
Orthoph- 0.7 1 50
osphate
Tau(r) = ([SW]/[RW])Tau(w), where Tau(w) = replacement (residence) time of H2O =
36,000 yr; RW = river water; SW = seawater, and concentration in micromoles per litre
= VtM.
Major Processes of Organic Matter Decomposition in Marine Sediments.
Reactions succeed one another in the order written as each oxidant is completely
consumed
Oxygenation (oxic)
CH2O + 02 = CO2 + H2O
Nitrate reduction (mainly anoxic)
5CH2O + 4NO3- = 2N2 + CO2 + 4HCO3- + 3H2O
Manganese oxide reduction (mainly anoxic)
CH2O + 2MnO2 + 3CO2 + H2O = 2Mn++ + 4HCO3-
Ferric oxide (hydroxide) reduction (anoxic)
CH2O + 4Fe(OH)3 + 7CO2 = 4Fe++ + 8HCO3- + 3H2O
Sulfate reduction (anoxic)
2CH2O + SO4- - = H2S + 2HCO3-
Methane formation (anoxic)
2CH2O = CH4 + CO2
Note: Organic matter schematically represented as CH2O.
Concentration Changes of Some Major Seawater Constituents Upon
Reacting with Basalt at High Temperatures
Concentration (a mM = a millimoles/litre = a x 10^-3 moles/litre = a x 10^-6 moles per
millilitre, and e.g. concentration in kg/kg of Mg = 54 x 24 x 10^-6 = .00129 kg/kg)
Constituent Seawater Galapagos Delta (mM)
Mg++ 54 0 - 54
Ca++ 10 35 25
K+ 10 19 9
SO4-- 29 0 - 29
H4SiO4 0.1 ~20 ~20
Delta Ca++ minus
Delata S04-- - - 54
Note: mM = ~millimoles per liter.
Data are for the Galapagos spreading center at 350C and are taken from the
extrapolation of Edmond et al. (1979).
Delta = concentration difference between 350' C ~Galapagos water and ~seawater.
Delta Ca++ minus Delta S04-- = total Ca++ released to solution.
Change in Concentration in Interstitial Water for Various Ions versus
Depth in a Sediment from the Brazil Basin, South Atlantic Ocean (Station CH 1 1 ~5-
DD)
Sediment Concen Change - Pore Water Overlying Seawater (mM)
Depth -tration
(cm) pH DNa+ DMg++ DCa++ DK+ DHCO3- DS04--
0 7.4 0.00 0.00 0.00 0.00 0.00 0.00
5 7.5 0.07 -0.04 0.17 -0.05 0.19 0.05
15 7.3 0.09 -0.35 0.45 -0.11 0.25 0.04
30 7.5 0.46 -0.42 0.50 -0.08 0.34 0.06
60 7.5 0.45 -0.58 0.76 -0.11 0.68 0.06
100 7.2 0.56 -0.78 0.97 -0.16 0.82 -0.01
195 7.4 0.95 -1.09 1.18 -0.26 1.12 -0.13
Note: Negative Delta values refer to uptake by the sediment (loss from pore water).
mM = millimoles per litre; = 10^-3 moles per litre.
Rates of Addition via Rivers of Major Elements to the Ocean (as Dissolved Species)
and Rates of Net Loss from the Ocean by Transfer of Sea Salt to the
Continents via the Atmosphere
Rate of Addition Rate of Net Sea Salt Loss
Species from Rivers, (Tg/yr) to Atmosphere (Tg/yr)
Cl- 308 40
Na+ 269 21
S04- - -S 143 4
Mg++ 137 3
K+ 52 1
Ca++ 550 0.5
HCO3- 1980 --
H4SiO4-Si 180 --
Tg = 1012 g. Based on river water input of 37,400 km3/yr; includes
pollution.
The Oceanic Chloride Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers (natural) 215 Net sea-air transfer 40
Rivers (pollution) 93 Pore-water burial 17
Total 308 Total 57
Long-Term (Balanced) Budget
Inputs Outputs
Rivers 215 NaCl evaporative
deposition 166
Net sea-air transfer 40
Pore-water burial 9
Total 215
Note: Tg = 1011 g. Replacement time for Cl- is 87 million years.
The Oceanic Sodium Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers (natural) 193 Cation exchange 42
Rivers (pollution) 76 Net sea-air transfer 21
Pore-water burial 11
Total 269 Total 74
Long-Term Budget
Inputs Outputs
Rivers 193 NaCl deposition 108
Net sea-air transfer 21
Cation exchange 21
Pore-water burial 6
Basalt-seawater reaction 37
Total 193
Note: Tg = 1012 g. Replacement time for Na+ is 55 million years.
The Oceanic Magnesium Budget (Rates in Tg/yr)
(Balanced) Budget for Past 100 Million Years
Inputs Outputs
Rivers 137 Volcanic-seawater
reaction 119
In biogenic CaCO3 15
Net sea-air transfer 3
Total 137
Note: Tg = 1012 g. Replacement time for Mg++ is 13 million years.
The Oceanic Potassium Budget (Rates in Tg/yr)
Long-Term (Balanced) Budget
Inputs Outputs
Rivers 52 Fixation on clay
near river mouths 4
Volcanic-seawater Sea-air transfer 1
reaction (high-
temperature 30
Total 82 Low-temperature volcanic-
seawater reaction or
slow fixation in deep
sea or reverse weathering 77
Total 82
Note: Tg = 1012 g. Replacement time for K+ is 10 million years.
The Oceanic Calcium Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers 550 CaCO3 deposition:
Volcanic-seawater Shallow water 520
reaction 191
Cation exchange 37 Deep sea 440
Total 778 Total 960
Budget for Past 25 Million Years
Inputs Outputs
Rivers 550 CaCO3 deposition:
Volcanic-seawater Shallow water 240
reaction 191 Deep sea 440
Cation exchange 19 Evaporitic CaSO4
deposition 49
Total 760 Total 729
Note: Tg = 1012 g. Replacement time (rivers only) for Ca is 1 million years.
The Oceanic Bicarbonate Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers 1980 CaCO3 deposition:
Biogenic pyrite Shallow water 1580
formation 145
Deep sea 1340
Total 2125 Total 2920
Budget for Past 25 Million Years
Inputs Outputs
Rivers 1980 CaCO3 deposition:
Biogenic pyrite Shallow water 730
formation 145
Deep sea 1340
Total 2125 Total 2070
Note: Tg =1012 g. Replacement time for HCO3- (river input only) is 83,000 years.
The Oceanic Silica Budget (Rates in Tg/yr).
Present-Day Budget
Inputs Outputs
Rivers 180 Biogenic silica deposition:
Basalt-seawater Antarctic Ocean 117
reaction 30 Bering Sea 13
Total 210 North Pacific Ocean 7
Sea of Okhotsk 7
Gulf of California 5
Walvis Bay 3
Estuaries 38
Other areas <13
Total 190-203
Tg = 1012g. To convert to Tg of SiO2, multiply by 2.14. The replacement time
for riverborne H4SIO4 is 21,000 years. The removal value for estuaries may be a
maximum.
The Oceanic Phosphorus Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers: Dispersed authigenic P 1.0
Natural dissolved P Organic P burial 2.2
(organic plus ~ortho-P) 1.0 CaCO3 deposition 0.1
Dissolved P from Adsorption on volcano-
pollution 1.0 genic Fe oxides 0.7
Particulate reactive P Phosphorite formation <0.1
(mostly pollution) 3.0
Rain (plus dry Fish debris deposition <0.02
fallout) 0.3
Total 5.3 Total 4.0
Long-Term (Balanced) Budget
Inputs Outputs
Rivers: Dispersed authigenic P 1.0
Dissolved ortho-P 0.4 Organic P burial 1.1
Dissolved organic P 0.6 CaCO3 deposition 0.1
Adsorption on volcano-
Particulate reactive P 1.5 genic Fe oxides 0.7
Rain (plus dry fallout) 0.3 Phosphorite formation 0.1
Total 2.8 Total 3.0
Tg = 1012 g. The replacement time for phosphorus via river addition (of
dissolved orthophosphate only) is 50,000 years.
The Oceanic Nitrogen Budget (Rates in Tg/yr)
Present-Day Budget
Inputs Outputs
Rivers: Organic N burial in
sediments 14
Natural dissolved Denitrification 40- 120
inorganic N (88% as Total 54- 134
NO3- -N) 4.5
Natural dissolved
organic N 10
Pollutive dissolved N 7
Particulate organic N 21
Rain and dry deposition 20
Fixation of N2 10-90
Total 73-153
Note: Tg = 1012 g. The replacement time for NO3- added by rivers is 72,000 years.
FIGURES
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