A lake has an input of 1 g P m-2 yr-1. Assuming that all the P is taken up
(assimilated) and phytoplankton biomass has a Redfield molar ratio of 106:16:1 (C:N:P),
a) how much algal biomass (dry weight m-2 yr-1) could be supported in this lake (Hint:
calculate moles of C relative to P, then convert to g C, then assume dry algal tissue is
50% C by weight).
b) how much N (grams) is required for this amount of algal biomass?
2. [30 points] To fully denitrify 1000 gallons of water with a nitrate-N concentration of 17 mg
a) how much C (moles) as glucose would it take? (Hint: balance half reactions for nitrate
conversion and carbon oxidation, then couple the two reactions on the basis of
electrons, i.e., cancel the electrons out, then use stoichiometry in the balanced full
reaction to convert moles of nitrate into moles of C)
b) how much C (moles) as methanol would be required?
c) how much S (moles) as sulfide would be required?