ch 3

Question 1

percentage of chloride, salt, and water in ocean

Answer 1

96% water

55% chloride

30% salt

the rest is sulfate and other things

Question 2

what elements are found in seawater

Answer 2

most of the 90 naturally occurring elements but in relative proportions different to those in crustal rocks

Question 3

molarity

Answer 3

mols/L

Question 4

molality

Answer 4

moles/kg

Question 5

what units do we use for organic matter compounds

Answer 5

not molarity or molality, we use g/l bc the molecuels are huge and highly variable

Question 6

solute size

Answer 6

less than 1 nm

Question 7

colloid size

Answer 7

bc 1 nm to 0.1 um

Question 8

solids size

Answer 8

greater than 0.1 um

Question 9

residence time formula

Answer 9

pool size/ (sum of fluxes in OR sum of fluzxes out)

Question 10

if mixing time < than residence time

Answer 10

the substances are conservative properties of water and their relative ratios dont change - they are all diluted to the same extent

CONSTANT PROPORTIONS

Question 11

what is the mixing time of the world oceans

Answer 11

around 1000 years

Question 12

what is the law that describes conservative substances

Answer 12

the law of constant porportions

Question 13

how can we get an excelent approximation of Salinity by measuring one concentration

Answer 13

measure chlorinity or [cl-] which is easier to measure and multiply by 1.81

Question 14

how does a CTD work

Answer 14

apply a volatge from a positive and negative electrode and the sodium ions flow and create a current

measuring the waters conductivity

Question 15

why are the non conservative elemnts not conservative

Answer 15

they cycle rapidly and are used in biological processes

found in small and highly variable amounts

not uniformly distributed

Question 16

what elements are non conservative

what compounds are non conservative

Answer 16

C,N,O,P

nitrates, ammonium, phosphates

Question 17

what kind of elements are the trace elements

Answer 17

atomic number greater than 20

transition metals

metal and heavy metals

alkalai metals

Question 18

what is the concentration of trace elements

Answer 18

less than 0.05 umol.kg

Question 19

what are the sources of trace metals

Answer 19

runoff/ river- mobilized during weathering

atmosphere

human sources/ anthropogenic

diagenesis

hydrothermal activity

Question 20

what is the atmosphere a source of trace metal for

Answer 20

As and Pb

Question 21

what is diagensis

Answer 21

sinking particles attatch to larger things and go to the bottom of the ocean

chemical. reactions solubilize them and they then diffuse across the sediment water interface

Question 22

what are the antrhopogenix sources of trace metals

Answer 22

burning of fossil fuels

mining and and industrial activities

Question 23

what are the sinks for trace metals

Answer 23

adsorption- onto surfaces

percipitation

incorporation into biological material

they are already in such small amounts and these processes remove them

Question 24

what are the macronutrients

Answer 24

C

N

P

Question 25

atom =

Answer 25

nucleus + electrons

Question 26

what dictates the chemical properties and reactivity of an element

Answer 26

the number of electrons

Question 27

what is the nuclear number

Answer 27

the number of protons and electrons

Question 28

what are unstable isotopes

Answer 28

radioactive isotopes or radionucleotides they decay over time and release particles to become different elements

Question 29

what is the radioactive decay law

Answer 29

rate at which a radionuclide decays is directly proportional to the number of atoms presen

Question 30

what is the decay constant

Answer 30

the statistical likelihood that an average atom of a given radionuclide will decay in a certain TIME

Question 31

what are the three sources ofr radionucleotides

Answer 31

primordia cosmogenic artificail

Question 32

primordial radionucleotides

Answer 32

present at the creation of the earth billion of years half lives of U235,238 and Th 232 and then become daughter Pb 206-208 with much shorter half lives

Question 33

what are cosmic rays

Answer 33

in cosmogenic radionucleotides protons and alpha particles- charges praticles that enter the earths atmosphere from outer space high energy cause SPALLATION- fragmentation of gas nuclei

Question 34

comsogenic radionucleotide of N

Answer 34

N attacks- releases proton and becomes unstable C14 releases y and electron and becomes N14 again

Question 35

what does radioactive decay lead to

Answer 35

exponential decrease in nucleotide numbers over time

Question 36

how can we calculate the age of radioactive elemnts

Answer 36

if we know the current and initial CONCENTRATION of parent and daughter nucleotides

Question 37

what do we use for dating of radioactive elements

Answer 37

Primordial and Cosmogenic

Question 38

what is the starting assumption of measuring parent c 14 today

Answer 38

that the ratio of c14/12 is the same not true bc c14 has since decayed, production is not constant due to atmospheric flux of cosmic rays (sunspot activity and earths magnetic field) anthropogenic input from atom bomb testing (increases c14) and burning of fossil fuels (decreases fossil fuels bc they have low 14)

Question 39

suess effect

Answer 39

burning fossil fuels in the 1850s introduced old carbon to the atmosphere reducting the C14/12 ratio dilute current cO2 with cO2 that has high c12 and no c14

Question 40

So what to do with the variable production rates of C-14 in the past?

Answer 40

can use values from literature or nearest value we can get

Question 41

using radioactive tracers from atom bomb testing and leakage from nuclear plants

Answer 41

use C14 as it is a fission product since testing was from 1958-1965, we can see the spikes in ocean and track its movement seeing horiontally how far it has gone- THC and horizontal currents how far it made it into the deep ocean- vertical mixing, advection

Question 42

When dealing with small concentrations of a tracer:

Answer 42

it is much easier to calculate such concentrations of substance by counting the number of the radioactive decays per unit time

Question 43

non radiocative tracers

Answer 43

like CFCs – have to be measured by more traditional chemical analytical methods -> much bigger error bars

Question 44

stable carbon isotopes

Answer 44

c12 and 13- dont break down over time, redistributed in processes that may favour one over the other and leads to the changing of the ratio

Question 45

Since the isotopes have the same number of protons and electrons ->they have practically the same

Answer 45

chemical properties

Question 46

But having different number of neutrons, they have

Answer 46

different atomic mass – so they will have different PHYSICAL properties

Question 47

what elements isotopes will we use for climate

Answer 47

o and h bc they are in water O18 is heavier, easier to percipitate, harder to evaporate measure how much 018 there is, tells us volume of ice at glacial period and indirectly the water and air temp easier to percipitate- tells us how far the air masses moved in the glacial period- the water is enriched in heavier isotope of O and the ice is enricehed in lighter O isotope

Question 48

what is another application of stable isotpes

Answer 48

B11 and 10 the ratio in water is preserved in shells of microfossils and the ratio depeneded on the pH at the time so we would know the partial pressure of CO2 in the water when they formed

Question 49

exceptions to the rule of constant proportions

Answer 49

1. where river water enters 2. SO42-- anoxic enviroments used by bacteria to respire organic mater and decrease SO42- and increase s2- 3. salt excluded from ice during formation 4. deviations in Ca due to CaCO3 formatino and dissolution- surface dwelling plankton 5. hydrothermal emission- depleted in SO42- and Mg2+ 6. shallow water- high E and low P- evaporites formed in areas of restricte dmixing 7. bursting and aeorosol formation from bubble ejection- different ions ejected to diff degrees 8. water trapped in sediments- pore / interstitial water- limited exchange