Salts In The Sea

Question 1

What percentage of sea water is dissolved salt?

Answer 1

3.5%

Question 2

What is the typical salinity of the sea?

Answer 2

30-38 psu

Question 3

What are the units of salinity?

Answer 3

Parts per thousand (ppt)
Grams per kilograms (g/kg)
Practical salinity units (psu)

Question 4

What are the major constituents of seawater?

Answer 4

Salt (NaCl)

Question 5

What are the minor constituents of seawater?

Answer 5

Lithuim, iodine

Question 6

What are trace components?

Answer 6

Concentration less than 1 part per billion - copper, radionuclides

Question 7

What are the nutrients in seawater?

Answer 7

nitrogen, phosphorus, silicon

Question 8

What are the gases in seawater?

Answer 8

N, O, CO2, inert gases

Question 9

What are the organics?

Answer 9

Not part of salinity - dissolved and particulate material of biological origin.

Question 10

What is sodium chloride?

Answer 10

85% of salts in the sea
Na+ (cation)
Cl- (anion)
NaCl concentration - 30.11 g/kg

Question 11

Why is there not the same weight of Na and Cl in the oceans?

Answer 11

Cl - 19.35/35.5 = 0.545
Na - 10.76/23.0 = 0.468
Different molarities

Question 12

How much salt is in the sea?

Answer 12

4.55 x 10^16 tonnes

Question 13

Where are the trace elements usually from?

Answer 13

rows 5, 6 and 7

Question 14

What are the nutrient constituents?

Answer 14

Nitrate, Nitrite, Ammonia, Urea, organic compounds

Question 15

What are inorganic particles?

Answer 15

Aluminosilicate rock

Question 16

What are pollutants?

Answer 16

xenobiotic compounds and natural compunds

Question 17

How do major salts get into the sea?

Answer 17

riverine inputs
atmospheric inputs - volcanoes, biogenic, wind blown, comic
hydrothermal vents
glacial transport

Question 18

What happens to river salts?

Answer 18

Conservative - not changed by biological or chemical processes
Non conservative - react with chemical or biological processes

Question 19

How do you calculate residence time?

Answer 19

residence time (yrs) = total amount of substance (tonnes) / sum of fluxes into or out of the reservoir (tonnes per yr)

Question 20

What is flux?

Answer 20

Rate of transfer in 10^3 km^3 per year

Question 21

How do you calculate salinity from chlorine?

Answer 21

Salinity = Chlorinity x 1.80655

Question 22

How can you measure salinity?

Answer 22

Gravimetric - evaporate water away and measure salts remaining
Chlorinity - measure concentration of chloride and calculate salinity from the constancy of composition principle
Conductivity - measuring the ability of the water to carry an electric current.