Conversion Factors, Estimates and Ranges

These are some rough estimates of the relationships between major parameters. We will try to derive or estimate most of them. These factors are very useful for checking answers.

 

Weight and volume

1 cm^3 of cells weighs 1 gram - i.e. they weigh the same as water to a first approximation.

Algal cells are about 30% dry weight.

The dry weight of cells contains approximately 35% carbon by weight.

 

Photosynthesis and pigments

Chlorophyll ranges from about .5 to 5% of the dry weight of the cell.

C/Chla ratios range from by weight

35% / 0.5% = 70

35% / 5% = 7

6 just in the photosynthetic apparatus (not the entire cell C) Shuter 1979

 

Maximum photosynthetic rate

 

2 mg O2 mg Chl-a^-1 hr^-1 (Reynolds 1984)

2 to 5 mmol O2 mg Chl-a^-1 hr^-1 (Kirk 1994)

5 to 35 mg O2 gram_dry_mass ^-1 hr^-1

using this higher value

35 mg O2 = 1 mmol = 12 mg C

12 mg C per gram_dry_mass ^-1 hr^-1

1 gram_dry_mass = 350 mg C

12 mg C (350 mg C_in_the_cell)^-1 hr^-1 = 0.034 specific growth rate

 

 

Respiration

Respiration can be estimated as either (from Shuter 1979):

15% of mmax

0.036 * total_cell_carbon^-0.786 pgC cell^-1 hr^-1