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Marine Geochemistry
Final Review for ESS 144: Marine Chemistry
76
Chemistry
Undergraduate 4
04/30/2012

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Term
why are surface waters at the equator slightly lower in O2
Definition
b/c of equatorial upwelling bringing old, respired waters to the surface
Term
What are the three common forms of Nitrogen
Definition
NO3 (Nitrate)
NH4 (Ammonium)
N2O (Nitrous Oxide)
Term
What are the two types of phosphate in the ocean?
Definition

Orthophosphate, HPO4 2- (90%)

Phosphorus, PO4 3- (10%)

Term
What are the two common forms of Silica in the ocean?
Definition
opaline silica (a-SiO2) silacious acid (Si(OH)4) (95%)
Term
Photosynthesis equation
Definition
CO2 + H2O + sun + nutrients --> O2 + CH2O
Term
Respiration equation
Definition
CH2O + O2 --> CO2 + H2O + nutrients + energy
Term
What reaction explains why phosphate and oxygen profiles are the mirror images of each other?
Definition
Respiration; O2 and P are on opposite sides of the respiration equation
Term
What is DOP? Where does it come from?
Definition
DOP stands for dissolved organic phosphate
Comes from excretion and degradation products of organisms
Term
What are the main inputs and removals of phosphorus in the ocean?
Definition
Rivers are the main inputs of P while P is mainly lost via removal to sediments
Term
Steady State
Definition
New Production (input) =Export Production (removal)
Term
What are Alkenones used to detect?
Definition
temperature of seawater in which coccoloths grow
Term
Which organisms produce Si exoskeletons?
Definition
Diatoms, radiolarians, and siliceous sponges
Term
How does the Si cycle differ from the N & P cycle?
Definition
N&P get remineralized, whereas Si is dissolved; since dissolution is a slower process, deepwater [Si] is higher than [P] or [N]

Si is used by siliceous organisms whereas P & N are used by all photosynthetic organism

Si is recycled in surface waters LESS than N or P, but is buried more efficiently than N or P
Term
Why is the concentration of Si in Antarctic Intermediate Water high
Definition
Because there are a lot of diatoms and other siliceous organism living in the Antarctic ocean
Term
What is the dominant ocean (sediment) reservoir of C
Definition
Calcium Carbonate (CaCO3)
Term
What are the two mineral forms of CaCO3?
Definition
Aragonite and Calcite
Term
What is the difference between Calcite and Aragonite?
Definition
Calcite is found in deep sea sediments while aragonite is found in shallow sea sediments

Calcite is thermodynamically stable, Aragonite is more soluable
Term
What is the saturation index and how is it related to Ksp
Definition

Ω = [Ca2+][CO32-]/K’sp

Supersaturated: Ω > 1

Undersaturated: Ω < 1

At saturation, K'sp = 1 and Ω = 1

Term
How are the depths of the Lysocline and the CCD related and what are they?
Definition
Lysocline = the depth at with an observable change in the %CaCO3 begins

CCD = Calcite Compensation Depth is the depth as which the rate of supply of CaCO3 equals the rate of dissolution of CaCO3 (also called the snow line)

The Lysocline is about 1000-1500m above the CCD
Term
What is the pool size of DOC? of POC?
Definition
Pool size of DOC = 685 GtC
Pool size of POC = 30 GtC
Term
What are the main sources of DOC in the ocean?
Definition
Organisms (excretion, cell lysis, breakdown of particles, and sloppy feeding)
Term
What eats DOC?
Definition
Bacteria
Term
What are the [DOC] in surface and deep waters
Definition
Deep water [DOC] = 40 uM Surface water [DOC] = 100 uM
Term
How much DOC is readily identifiable molecularly?
Definition
10% in readily identifiable compounds (e.g., amino acids, carbohydrates, lipids)
Term
What is the approximate 14C age of DOC in the N Atlantic and N Pacific
Definition

N Atlantic 14C DOC age = 4000 years

N Pacific 14C DOC age = 6500 years

Term
As anthropogenic CO2 enters the ocean, what will happen to [DIC]?
Definition
it will increase
Term
Black Carbon
Definition
the relatively inert carbon that is formed during incomplete combustion such as in wildfires, e.g., soot, charcoal, and elemental carbon
Term
In terms of 14C age, what is oldest and what is youngest of DOC, DIC, and black carbon in DOC?
Definition
DIC is youngest, Black Carbon in DOC is oldest
Term
What are the two main forms of particles that fall into sediment traps in the ocean?
Definition
Fecal pellets
Marine snow
Term
What are the two ways to collect POC in the ocean?
Definition
1. Traps collect sinking POC and POM
2. Pumps collect suspended POC and POM
Term
Does the concentration of POC vary w/season?
Definition
Yes; highest in October, lowest in February, moderate in june/july
Term
what is the flux of POC out of surface oceans? deep oceans?
Definition
Flux out of surface: 10 – 200 mg C/m2/day
Flux in the deep ocean: 1 – 20 mg C/m2/day

POC flux decreases with depth
Term
What are the two ways a biomarker can be measured?
Definition
gas chronatography
mass spectrometry
Term
What is the pe of oxic seawater
Definition
pe = 12.6
Term
what is the pe of organic rich seawaters
Definition
pe = 0
Term
Electron Capture
Definition
an inner shell electron is captured by a proton to form a neutron

Result is same atomic mass but atomic number is one lower

19K40 --> 18Ar40
Term
Alpha Decay
Definition

the unstable nucleus ejects a small part of itself; this particle consists of 2 neutrons and 2 proton

results is atomic mass 4 units larger and 2 atomic numbers lower

238U -> 230Th
Term
Beta Decay
Definition
a neutron spontaneously breaks apart into a proton and a high energy positron

results is a nucleus with the same atomic mass and an atomic number one higher

14C -> 14N
Term
What are the major 2 long-lived fission products from nuclear bombs?
Definition
Strontium 90 (90Sr) (half life = 29 years)
Caesium 137 (137Cs) (half life = 30.2 years)
Term
Nano Nutrients
Definition
Fe, Mg, Zn
Term
Why is the input of P to the deep ocean (B) so low, compared to the amount of P that is utilized during primary production in the surface ocean?
Definition
Most of the P utilized during primary production is remineralized in the surface ocean by biological processes and recycled
Term
why is Si productivity more predominant in upwelling/divergence regions?
Definition
because there is much less surface water recycling of Si, a greater proportion of Si productivity (as compared with non-Si productivity) must be supported by “new” nutrients (or at least new Si)
Term
What are the reasons to think N is the ultimate limiting nutrient?
Definition
N is regenerated more slowly
Term
What are reasons to think that P is the ultimate limiting nutrient?
Definition
N2 fixation can alleviate N limitation, but there is no equivalent process to alleviate P limitation
Term
What is higher in the North Atlantic than in the North Pacific?
Definition
Salinity
CO3
O2
pH (more basic)
Density
Term
What is higher in the North Pacific than in the North Atlantic?
Definition
DIC
Nutrients
14C age
Acidity
Term
Is the concentration of nutrients higher or lower than the concentration of conservative elements in the ocean?
Definition
Lower
Term
What process is responsible for the change in [DIC] in deep waters as it moves from the North Atlantic to the North Pacific?
Definition
Remineralization
Term
In the formation of evaporites, what compound is first to form?
Definition
Calcite
Term
What is the most dominant mineral in evaporites?
Definition
Halites (or NaCl)
Term
What element is almost completely removed from seawater during hydrothermal processes?
Definition
Magnesium
Term
Where is Si productivity highest?
Definition
In regions of divergence or upwelling (Coastal CA, Antarctic, and Equator)
Term
How does the flux of phosphorous change with depth?
Definition
It decreases (except at 1500m)
Term
What regions of the ocean are iron poor (Fe limited)?
Definition
The Southern Ocean, Equatorial Pacific, and North Pacific (HNLC regions)
Term
Where are nutrient concentrations > 0 umol/L in the surface ocean and why?
Definition
In high-nutrient, low-chlorophyll regions (HNLC regions); because there regions are iron limited
Term
How does Ksp change with temperature and pressure?
Definition
Ksp increases with increasing pressure
Ksp increases with decreasing temperature
Term
How does CaCO3 solubility change with temperature and pressure
Definition
CaCO3 is more soluble at high pressure and low temperature (the conditions of the deep ocean)
Term
How does pH change with depth
Definition
it decreases slightly (becomes more acidic)
Term
How does CaCO3 act as a buffer for ocean CO2 systems?
Definition
The uptake of CO2 makes waters more acidic, which makes CaCO3 more soluble, and the dissolution of CaCO3 makes waters more basic
Term
how large does organic matter/carbon need to be to qualify as a particle
Definition
> 1 micromole
Term
Where in the ocean would there be a minimum flux of POC?
Definition
in the gyres, where productivity is low
Term
Define pe
Definition
the representation of the activities of electron donors in a solution
Term
Define pH
Definition
Representation of the activities of hydrated protons in a solution
Term
What makes Calcite?
Definition
foram and cocoliths
Term
What makes aragonite?
Definition
pteropods and corals
Term
Atomic Number
Definition
number of protons
Term
Atomic mass
Definition
= number of neutrons + number of protons
Term
Marine Snow
Definition
organic material falling from upper waters to the deep ocean
Term
What is the order in which O2, denitification, sulfate reduction, methane fermentation are used to oxidize carbohydrates in the sediment?
Definition
O2 is the first oxidant used, then NO3, then SO42, then CH4
Term
Calcium Carbonate Formation Equation
Definition
2HCO3 + Ca → CaCO3 + H2O + CO2
Term
Phosphorous Equation
Definition
H3PO4 → H + H2PO4 → 2H + HPO4 → 3H + PO4
Term
Silica Dissociation
Definition
Si(OH)4 → SiO(OH)3 + H
Term
What are biomarkers?
Definition
A molecule that retains the structure or heritage of its origin
Term
reactivity of half DOC in the surface oceans
Definition
labile
Term
How is SiO2 transported to sediments so quickly?
Definition
via fecall pellets
Term
What pumps a large amount of water in the ocean?
Definition
sponges
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