carbonate system

Question 1

role of carbonate system

Answer 1

regulate pH of water (oceans, lakes, rivers) as well as C° of CO2 in atm

Question 2

carbonate cycle

Answer 2

• natural buffer in ocean
• most abundant natural weak acid
• atm CO2
• exchange photosynthesis
• dossolution of carbonates

Question 3

nitrogen/phosphate cycle

Answer 3

plankton nutrient
N = fixation from atm nitrogen
P : dissolution of P rocks

Question 4

sulfide cycle

Answer 4

only in anoxic environment
sulfate reducing bacterias

Question 5

formula pH

Answer 5

pH = pka + log(weak base/weak acid)
pka = -log(Ka)

Question 6

common (rock forming) carbonate minerals

Answer 6

calcite (trigonal, CaCo3)
dolomite (trigonal, Ca,MgCO3)
aragonite (orthorombic, CaCO3)=> metastable and transforms into calcite

Question 7

dissolution of calcite in water

Answer 7

Kcalcite = [Ca][CO3]=e-8,48
[ca]=sqrt(e-8,48)= 2.4mg/L

in average water : dissolved Ca 14.7 mg/L

Question 8

calcite and photosynthesis

Answer 8

direct coupling btw bio reactions (photosynthesis, decomposition) involving CO2 and carbonate mineral reactions

Question 9

hypolymnion

Answer 9

closed system where there is pratically no exchange btww atmosphere and bottom water, TIC is constant

Question 10

atmospheric pressure of CO2

Answer 10

today = 413 ppm=e-3?38 atm
mH+ = sqrt(e-7,8*PCO2)

pH=-log(H+)

Question 11

alkalinity

Answer 11

measure of the capacity of water to neutralize stronf acid
tot alk = [HCO3-]+2[CO32-]-[H+]

determined by titration with HCl or H2SO4