Natural Organic compounds

Question 1

DOC vs DIC vs POC

Answer 1

dissolved organic carbon
- dominant form of organic carbon in natural waters
- areas rich in DOC: Lake water, canopy drip, Interstitial water, emergent plants
- areas poor in DOC: snow melt, groundwater, precipitation,

dissolved inorganic carbon
- dominated by HCO3 at near neutral pHs

Particulate organic carbon
- undissolved organic carbon

Question 2

Humic acids

Answer 2

• dissolve in water with a pH greater than 2

Question 3

Fulvic acids

Answer 3

dissolve in water at all pH values

Question 4

Humin

Answer 4

• insoluble in water–> POC
  -adsorbs metals onto surfaces

Question 5

Decay of organic kinetics

Answer 5

• follows first order kinetics
• τ1/2= (ln1/2)/-k Time it takes for half of the original concentration to degrade

Question 6

Anaerobic bacteria

Answer 6

• first reduce nitrate: NO3–> NO2–> N2(gas)
  -second reduce sulfate: SO4–> S
• Finally reduce carbon: CO2–> CH4