The stoichiometric equation for algal growth can be summarized as
105 CO2 + 16HNO3 + H3PO4 + 122H20 ---> (CH20)42(CH2)64(NH3)16 H3PO4 +
170 O2
The molar ratio of N to P needed for algal growth (16:1)
a) In a typical year in the 1990s, the Eastern SHore of Maryland
raised approximately 600 million chickens, generating 658,000 metric
tons of manure---"enough to lay a yard-wide, foot -high swath from
Maryland to Salt Lake City."
THis chicken manure is about 90% carbon by weight. Assume that the
other 10% consists solely of nitrogen and phosphorous in a molar ratio
of 5:3. If this manure is used as fertilizer and all of the nitrgen
and phosphorous from the manure reaches the CHesapeake Bay and is used
by algae to produce biomass, what is the mass (in g ) of biomass
produced in the Bay from the stoichiometric equation above? What is
the limiting nutrient (N or P)?
b) How many grams of oxygen wil be needed to biodegrade all of this
biomass according to the reverse of the chemical equation above? If
the average concentration of oxygen in the Bay is 8.9mg/L, what volume
of water (in L) could become anoxic due to the remineralization
(decomposition) of all this algae/biomass? How does this volume
compare to the total volume of the Chesapeake Bay (51x10^9 m^3)? |
