General biogeochemistry Flashcards
1
Q
Effect of Fe fertilization on ___ to ___ uptake ratio
A
Lowers the silicate to nitrate uptake ratio in diatoms (Hutchns and Bruland, 1988; Takeda, 1998), allowing for diatom-driven nitrate consumption to proceed to a much higher degree
2
Q
Depth of MLD in Antarctica during summer sea ice retreat
A
Shoals from to 20 m (from 60 m). (e.g., Robinson and Sigman 2008)
3
Q
BATS coordinates
A
31º40’ N 64º10’ W
4
Q
Chl.a concentration at BATS mg m-3
A
0.10 ± 0.08 mg m-3 (std deviations of the mean, not measurement error)
(vs. 0.8 ± 0.5 in SNA)
REF: see Biogeochemical Dynamics chapter 4
5
Q
Nitrate µmol kg-1 at BATS
A
0.04 ± 0.11 mg m-3 (std deviations of the mean, not measurement error)
(vs. 9 ± 6 in SNA)
(vs. 25 ± 2 at Antarctic Polar Front)
REF: see Biogeochemical Dynamics chapter 4
6
Q
Phosphate at BATS µmol kg-1
A
0.01 ± 0.02 mg m-3 (std deviations of the mean, not measurement error)
(note, vs. 1.8 ± 0.1 at Antarctic Polar Front)
REF: see Biogeochemical Dynamics chapter 4
7
Q
Silicic acid at BATS µmol kg-1
A
0.8 ± mg m-3 (std deviations of the mean, not measurement error) (note, vs. 14 ± 4 at Antarctic Polar Front)
REF: see Biogeochemical Dynamics chapter 4
8
Q
Definition of “high nutrients” in terms of nitrate and HNLC
A
> 2 mmol m-3 (i.e., greater than 2 mM)
9
Q
Ecumenical Hypothesis
A
Morel et al 1991
Combination of top down versus bottom up for different parts of the ecocystem i.e., parts of the system are controlled by grazing but the system as a whole is controlled by Fe limitation…
10
Q
C:N:P ratio variability as pertains to diatoms
A
Specifically: C:N:P of 80.5:10:1 for diatoms vs 134:18.6:1 for dinoflagellates., e.g., Sweeney et al 2000 (see also Arrigo 94:10:1 for diatoms; 150:20:1 for Phaeocystis)
Generally: Diatoms have lower than redfield proportions for C:N and N:P
REF: see Biogeochemical Dynamics chapter 4
11
Q
Average C:N ratio
A
6.6, but the net photosynthetic uptake if often ~ 10 to 12 (in “considerable excess” of 6.6) in Bering Sea, SNA, and Antarctic, e,g.
REF: Sambratto et al 1993, Biogeochemical Dynamics chapter 4
12
Q
IMPORTANT FIGURE
A
p. 120, Biogeochemical Dynamics chapter 4, Nitrate runs out before Phosphate; slope of the line is miraculously close to 16:1
13
Q
A) Why is there so little remineralization of nitrate in the euphotic zone?
A
nitrifying bacteria are inhibited by light
14
Q
Ammonium in the surface ocean
A
has a really low residence time! only measurable = from local remineralization of OM (REF: Sarmiento chpt 4) p 120
15
Q
Percentage of DOM cycled through bacteria (microbial loop) in the global surface ocean?
A
50% (Carlson, 2002)
16
Q
Percentage of total exported OM that is in the form of DOC?
A
10-30% (11% in Ross Sea to 52% in subtropical Pacific; Carlson et al 2002; Emerson et al., 1997). (33% in SS; Carlson et al., 1994) I.e., microbial loop is really important!
17
Q
Specific to the subtropical North Atlantic, Percentage of total exported OM that is in the form of DOC?
A
33% in SS; Carlson et al., 1994.
i.e., microbial loop is really important!
REF: Sarmiento chpt 4 p 122
18
Q
Two primary reasons microbial life = important for recycling of OM in the surface?
A
1) primary consumers of DOM
2) excrete of enzymes capable of breaking down the pool of OM into smaller soluble molecules
(Cho & Azam, 1988)
19
Q
e-ratio = ? (from Sarmiento text)
A
e-ratio = export ratio. e = (export production)/(primary production)
in contrast to f-ratio, which is (new prod)/(new+regen’d prod)
20
Q
relationship between e- and f-ratios over time and space?
A
supposed to equal one another, if you include lateral transport. Mass balance.
21
Q
why do e- and f-ratios have to = one another over space and time?
A
write eq for both ratios… primary prod cancels out…
22
Q
BATS nitrite concentration at 100m and at PNM
A
60 ±8 nmols 100m, peaked at 64 ± 14 nM at 120 m (PNM) (DECEMBER, 2009, Newell et al 2013)
23
Q
BATS nitrate concentration at surface, 100m, and 1000 m
A
0-10 nM in surface, up to 21 µM at 100m (DECEMBER 2009, Newell et al 2013)
24
Q
Ammonium concentrations at BATS in December
A
highest at 30 m – 26.2 ± 1.4 nM. Overall, = variable, but up to 26 nM in the upper 200 m. Undetectable below 300 m! (Newell et al 2013, December 2009)
25
side effect of light limitation by phytoplankton
nitrite excretion during assimilation of NO3- (Lomas and Lipschultz 2006)
26
Theorized percentage of nutrients supplied by subantarctic mode water in the southern ocean to productivity north of >30ºS in the Atlantic?
~75%! This from Sarmiento, Gruber, Dunne, Brezinski 2004 Nature paper
27
ratio of Si to N in diatoms that are not Fe stressed or light stressed
1:1
28
definition of Si* as a tracer
Si* = [Si(OH)4] - [NO3-]
Basically, Si in excess of NO3 assuming a 1:1 ratio of Si to NO3 (Sarmiento, Gruber, Dunne, Brezinski 2004 Nature Paper)...
In SAMW, concentrations of Si*= -10 µmol kg-1 to -15 µmol kg-1 are the lowest we were able to find anywhere at the surface of the ocean.
29
Three things you need to know in order to set up an 15N experimentt
incubation time determination: need to know
◦ size of pool
◦ turnover rates
◦ detection limits of analytical methods
30
types of amino acids that undergo transaminations; ones that don't
alanine, aspartate, glutamate are the usual products of transaminations; serine and threonine do not undergo transaminations (but do undergo dehydrogenation) (ref: wiki)
31
transamination
important for synthesis of non-essential amino acids; an amine group is switched with an O between a keto acid and an existing amino acid, resulting in a new keto and a new amino; this process accomplished by transamines (enzymes). The chirality of an enzyme is determined in these reactions (ref: wiki)
32
Diffusion - as defined by Jorge
occurs due to random motion of tracer molecules (molec diffusion) and also generally includes eddy diffusion - net effect of small-scale motion of water parcel that do not result in net advection. If one face of the cube has equal amounts of water flowing in and out, but if the water flowing in has a higher tracer concentration than the water flowing out, net accum of tracer will occur without net movement of water (advection)
33
Molecular diffusion
not proportional to the gradient in tracer concentration
34
Ekman transport
. great description, jorge's book p 23
35
What are the basic wind patterns respectively in the tropics, the mid-latitudes, and the high latitudes?
Trade winds in the tropics, westerlies in the mid-lats, polar easterlies in the high lats
36
Ekman transport
Water that is set directly into motion by the wind that feels the effect of th erth's rotation. Only extends to top 10-1000m of water column. 90º to the right of the wind in Nn Hemi, 90º to the left of the wind in Sn Hemi
37
Question - why doesn't surface water go in the same direction as the wind?
It feels the effects of the earth's rotation, resulting in 90º to the R ofthe wind, and to the L of the wind in Nthn and Sth respectively.
38
Fact: Ekman transport causes accum. of water on the western boundaries of oceans, resulting in a horizontal gradient of sea surface height.a Question - why doesn't downslope flow of surface ocean currents occur as a result?
Earth's rotation intervenes, causing the resulting flow instead to flow at a 90º angle to the expected down-gradient flow of water. Note: Gulf Stream results. Th western boundary flows are extremely concentrated and intense (because the water is piled up on the Western sides?)
39
Newton's 2nd Law
F = ma
F = force in newtons
m is mass in kg
a is acceleration in m s-2
equation for m: m=volume V times density p (jess note - "p" = rho sign actually)
40
Mechanism 1 of 3 for how Ekman transport can lead to upwelling or downwelling
Continent Margins. Winds that run parallel to coastline - if wind blows in such a way as to drive Ekman trasnport away from the coast, then = upwelling of deep waters (e.g., if wind is blowing north along the western boundary of a continent in the southern hemisphere)
41
Mechanism 2 of 3 for how Ekman transport can lead to upwelling or downwelling
Equator. Winds that blow along the equator can give rise to upwelling or downwelling via Ekman Transport (ET) -- trade winds have a strong easterly component... due to Coriolis, this results in R-ward turning currents in the Nthn Hemisphere, and L-ward turning currents in the Sthn Hemisphere, driving upwelling through Ekman Suction
42
Mechanism 3 of 3 for how Ekman transport can lead to upwelling or downwelling
Open Ocean. In regions wehre the direcition fo the prevailing winds switches from being easterlies to westerlies or vice versa (e.g., between 20º and 50º), Ekman Transport in the westerlies region will cause flow to go south; ET in the easterlies will cause flow to go north. In this way, IT will drive currents that will be convergent flow -- in this case, resulting in currents going towards each other, resulting in downwelling where they meet, in the subtropical gyres. The opposite occurs, because there are two currents going away from one another, resulting in upwelling in the subpolar gyres.
43
Question: why are the subtropics so "devoid" of life?
Due to Ekman processes! Aka, little upwelling to bring nutrients to the surface! The subtropical gyres experience Ekman mechanism in which wind patterns (easterlies switching to westerlies with latitude for subtropical gyres) results in Ekman Convergence where northward-marching Ekman-derived currents meet southward-marching Ekman-derived currents and subsequently cause downwelling in subtropical gyres. In contrast, subpolar gyre experience southward flowing currents running in the opposite direction of northward flowing currents, resulting in upwelling Ekman convergence! Also, equatorial convergence and coastal upwelling are and example of Ekman transport causing nutrient-rich regions. p 30 Jorge
44
Ekman Transport accumulates water, causing mounding up of water in ___ gyres and ____ clockwise circulation
Northern subtropical gyre, clockwise circulation
45
Counterclockwise circulation = anticylonic or cyclonic?
Anticyclonic
46
Northern Hemisphere subtropical gyre has ___ circulation (counterclockwise or clockwise?)
Clockwise, anticyclonic
47
Geostrophic
The balance between the Coriolis Effect and the effect of pressure gradients (which themselves are the results of "mounding" up of water due to Ekman transport) result in observed geostrophic flow. Note on pressure gradients -- in the north atlantic subtropical gyre, for example, which rotates clockwise, the effect of Ekman Transport (and because the 0 to 30ºN trade winds are easterlies i.e. west-going, creating northward flowing currents, which then meet the Ekman Transport-created southward-flowing currents from the westerlies, which are flowing from north to south, creating converging i.e. mounding waters. The mounding would create currents going DOWN the pressure gradient, but the rotation of the earth, the Coriolis forces, interferes, resulting in the clockwise rotating gyre in this case.
48
What is the symbol for density?
rho (ρ) as the symbol for density
49
1 cubic meter (m3) = ? liters
1 cubic meter (m3) = 1000 liters (L)
50
1000 liters (L) = ? cubic meters (m^3)?
1 cubic meter (m3) = 1000 liters (L)
51
1 L = ? cubic centimeters (cm^3)
1 L = 1000 cubic centimeters (cm^3)
52
1000 cubic centimeters (cm^3) = ? L?
1 L = 1000 cubic centimeters (cm^3)
53
1 m^3 = ? cm^3
1 m^3 = 1,000,000 cm^3 = 10^6 cm^3
54
10^6 cm^3 = ? m^3?
1 m^3 = 1,000,000 cm^3 = 10^6 cm3
55
density of freshwater compared to seawater?
at 4°C, FW density is 1000 kg/m3 (aka 1.0000 cubic cm = 1 gram). Note, one gram of mass is defined as the weight of one cm3 of freshwater at 4°C
56
σ (sigma) = ? (define)...
σ (sigma) = ρ - 1000
57
for example, if density (ρ) of water is 1025 kg/m3, then σ = ?
25
58
σ = 28 means ρ = ?
σ = 28 means ρ = 1028 kg/m3
59
Why is colder water more dense?
As water cools, H2O molecules pack more closely together (because the molecules are vibrating less at lower temperatures) and take up less volume
60
Equation for density?
density = mass/volume
61
for every 10m increase in depth, the pressure in the ocean increase by ~ ___ atmospheres? (a unit of pressure)
for every 10m increase in depth, the pressure in the ocean increase by ~1 atmosphere (a unit of pressure)
62
1 atmosphere = ? mm Hg
1 atmosphere = 760 mm Hg
63
1 bar = ? atmospheres
1 bar = 0.987 atmospheres
64
Generally accepted depth ranges for surface mixed layer, thermocline, and deep sea
surface mixed layer: upper 50-100m
thermocline: ~100m to ~1000m (delta theta/delta depth is greatest in thermocline -- biggest change in temperature)
deep sea: depths >1500m
65
mean sea surface temperature in the global open ocean
SST_global = 18°C, with a range of –1.5° to 29°C
66
range of salinity in the open ocean
30 to 37 (gms salt per kg seawater). Jess Q - does grams/kg equate to ppm?
67
saltiests parts of the surface ocean vs. freshest parts of the surface ocean
highest S in the Subtropical Gyres; lowest surface salinity at high latitudes, especially Arctic Ocean, where salinity approaches 28
68
contours of equal salinity are called
isohalines
69
contours of equal pressure are called
isopycnals
70
contours of equal temperature are called
isotherms
71
salinity of freshwater = ?
salinity of FW = 0. i.e. precipitation adds salinity of 0
72
evaporation (E) vs. precipitation (P). Where E exceeds P, the surface ocean salinity is ___?
Where E > P, the surface ocean salinity is HIGH
73
Where E < P, surface salinity is low or high?
LOW
74
E - P is highest at which latitudes, and lowest at which latitudes?
E minus P (E - P) is the highest at mid-latitudes (~ 30º) which causes the high salinity in Subtropical Gyres. Arctic has the lowest salinity causes due to river input of freshwater (Salinity=0). NOTE, units for E and P are in m/yr or cm/yr and represent the amount (depth) of water lost to evaporation (E) or added by precipitation (P) per unit time
75
Salinity of the deep sea?
S of Deep Sea: ranges from 34.4 to 35.
Surface ocean is 30 - 37.
Note: much less variability in deep sea S compared to surface ocean
76
Salinity of the surface ocean?
There is much less salinity variation in the Deep Sea (range from 34.4 to 35) compared to the surface ocean (30 to 37) (Fig. 23). Note: much less variability in deep sea S compared to surface ocean
77
Does pressure, temperature, or salinity have the greatest control over seawater density?
Pressure!
78
Why are polar oceans the best places for ventilation of deep sea to atmosphere?
Density of surface water approaches that of deeper water in polar regions (latitude > 60º) resulting in vertical isopycnals -- creating opportunity for surface waters to sink downward into the deep sea and deep sea to ventilate to the atmosphere because water column stability is low
79
Two primary sites of deep water formation?
far north Atlantic Ocean (near Greenland, Labrador and Norway) and in the far south Atlantic around Antarctica (primarily in the Weddell Sea), the surface waters get cold enough in winter to sink to great depths (between 2000m and the bottom at ~5000m). Also the Ross Sea off Antarctica in the Pacific Ocean (Fig. 25) has been shown to be an additional site of occasional deep water formation.
80
Henry's Law
Describes the solubility of a gas in equilibrium.
Henry’s Law = pressure of A * Solubility of A = [A]equilibrium concentration in mmol m-3
Significance: basically, that a gas above a liquid is directly prop’l to if the gas is in equilibrium
• If it is NOT in equilibrium (which is common), then and
• All of 3.3 Gas Exchange has to do with how to calc if NOT in equilibrium… (i.e., which do not have an anomaly of zero)
81
What accounts for saturation or undersaturation (of a gas?)
chpt3
82
Why are the disequilibrium patterns of CO2 so diff from O2? Describe the differences and their causes.
chpt3
i.e. CO2’s patterns are much broader in horizontal scale, and often opp in sign, than 02.. in places w supersaturation for CO2 (ie sources of CO2 to atmosphere), the O2 anomalies generally indicate a sink!
chpt3
83
Why, and how, = Rn-222 used as a tracer of gas exchange?
chpt3
84
Global Mean Trnsfer Velocity=?
chpt3
85
Stagnant Film Model
Non equilibrium gases (i.e. anomaly≠0). Basic concept – turbulent forces are suppressed at the air-sea interface. The result is TWO “stagnant films” of finite thickness, across which gases exchange diffuse. Combine Henry's Law and Fick's Law to create model.
86
Fick’s first law
chpt3
87
Henry's Law
chpt3
88
Define PO4*
| And why imp.
PO4* = (PO4 + O2/175 − 1.95). WHY DEVELOPED: e.g., to ID rel prop'ns of deep water from NADW and S. Oc., and b'c the other properties of those waters have a wide range of salinities and temperatures.
89
Surprising differences in contributions of C_org and CaCO3_org created by life in the surface. How much C_org is created vs how much buried? How much CaCO3_org is created vs how much buried?
the amount of carbon going into the formation of CaCO3 shells and cages is SMALL;
amount of C going into soft tissue is LARGE
BUT, the amount of CaCO3 carbon which is buried in sea floor sediments greatly exceeds the amount of soft tissue carbon buried. (most of the organic matter produced in the upper ocean is consumed in the upper ocean)
90
In one of Broecker's figures, he shows that the relative difference of SiO2 vs PO4 is higher in the Atlantic compared to the Pacific (at~3km). What is the mechanism, and is it biological or physical (abiotic)?
Mostly physical. The explanation is that the waters feeding the upper arm of the ocean conveyor belt are themselves lower in SiO2 compared to PO4, compared to waters entering the Pacific. BUT, this could be because diatoms in the S. Ocean source waters are doing a better job of stripping the SiO2 out compared to PO4. This is also due to Si running out before P. When Si runs out, then calcitic as opposed to silicic, organisms can come to the forefront (but diatoms dominate over coccoliths, e.g., when given replete nutrients!). (Note, At first glance, I thought it must have been because there are more diatoms in the Atlantic or something due to less Fe limitation, but actually it is just source waters.) Broecker p 102.
91
Revelle Factor
aka "buffer factor" - the sensitivity of pCO2 to changes in DIC. The typical surface ocean yeilds a buffer factor of ~10, i.e. a 1% increase in DIC yeilds 10% increase in pCO2
92
What percentage of CaCO3 makes it below the euphotic zone? What percentage of that is buried in seds?
50% below euphotic; 13% of surface export is buried (in contrast, burial of OM is only ~0.3% of surface export) (95% of OM is remin'd in water column -- NOT to be confused with euphotic zone)
93
Res time of ALK in the ocean?
10^5 years (sarmiento text p 359). NOTE, this is SHORT. BUT important for glacial interglacial feedbacks
94
Interesting anomaly pertaining to CaCO3 distribution in the oceans
Highest concentration of CO32- is actually where it is being consumed (surface ocean); lowest concentration is where it is being produced (deep sea).
95
2HCO3 + Ca2+ --->
CO2 + CaCO3 + H20
96
type of carbon used by photosynthesis
aqueous CO2
97
FEEDBACK: effect of increased oceanic acidity on coccolithophore production
would decr the prod of CO2 in the surface ocean, therefore increase the flux of CO2 from atmosphere into the ocean... thus feedback
98
what percent of opal produced in the surface is exported?
50%
99
mean ocean DIC?
2256 umol kg-1
100
preindustrial CO2?
280 ppm
101
current CO2
380-400 ppm
102
S:N uptake ratio?
~1
103
definition of Si*?
Si* = Si(OH)4 - NO3
| Note - this is because the uptake ratio of Si:N is 1:1
104
size of the circumpolar current?
400x size of the amazon
105
it takes 20% long for CO2 to equilibrate than if it behaved like O2... why?
this is because CO2 has to equilibrate with all of the ocean carbonate species. for every mol of Co2 added, it produces 20 mol of DIC. So, for one mol to dissolve (just assuming solubility, not including carbonate chemistry) is on the order of 9 days -- but when add chemistry, due 9 x 20 = 180 days = 1/2 a year, assuming MLD is 40m
106
average depth of the ocean
3800 m
107
concentration of CO2 in the surface
9.7 mmol m-3
108
average salinity of the ocean
34.78 % by weight average world salinity
109
DIC ocean
2200 mmol m-3
110
average oxygen concentration at the surface, assuming a temperature of 17.64 C and salinity of 34.78
241 mmol m-3
111
Henry's Law
partial pressure of a gas above a liquid is directly proportional to the concentration in that liquid
112
efficiency of the biological pump, and examples of places where = high vs. = low efficiency
E(sub)BP = ([NO3deep]-[NO3surf])/[NO3deep]
Note, in subtropical gyres, where nutrients are low, efficiency is about 100%. In southern oaen, E(sub)BP = 20-30%
113
Globally integrated carbon export from the surface (re sarmiento text)
12±4 Pg yr-1 (note = 10% of this is DOC; 90% is POC)
114
Compensation depth, Z(sub)C
depth where photosyth and resp are equal (as nick pointed out, is it where their rates are equal); the compensation depth in contrast is where the integrated rates are equal. depth at which irradiance is = to the compensation irradiance.
115
Critical depth, Z(sub)CR
Integrated photosynthesis versus integrated respiration (in contrast to compensation depth, which is just where one line = the other line), ... Required thickness of the MLD over which the integrated growth rate of phytoplankton is large enough to balance integrated respiration of that mixed layer.
116
in the critical depth plot, describe photosynthesis...
decreases exponentially with depth due to attenuation of the irradiance by adsorption and scattering
117
in the critical depth plot, describe respiration...
assumption: stays constant with depth
118
the ___ depth will always be greater than the ____ depth (in the critical depth plot)
critical depth will always be greater than the compensation depth
119
Compensation irradiance
irradiance at which photosynth is great enough to balance community respiration
120
Deep [O2]=
100-200 umol
121
[SO4]
28 mMol (28000 umol)
122
what percentage of primary production is consumed by mesozooplankton?
10-15% of primary prod in surface (Buithhuis 2010)
123
microzooplankton consume what percentage of primary prod?
59-74%
