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Exercise 10
Trichromatic Method for Mixed Phytoplankton Communities Containing Chlorophylls
a and b and Equal Amounts of Chlorophylls C 1 and C 2 with 90% Acetone Solvent
(Jeffery and Humphrey, 1975)
,
(Ca)(v)
Chi a (,lg/I or mg/m') = - - -
(V)(Z)
where Ca = 11.85 £664 - 1.54 £647 - 0.08 £630 and E6640 = AoM - A 750' etc., as
above.
where Cb =21.03 £647-5.43 £664-2.66 £630 and E047o=A647-A750' etc., as
above.
3
(CJ(v)
Chi ("I + ("2(llg/1 or mg/m ) = - - - -
(V)(Z)
where Cel + 2 = 24.52 £630 - 1.67 E664 - 7.60 E647 and E630 = A 630 - A 750, etc., as
above.
From these data the amount of pigments per cell of phytoplankton can be estimated:
Ilg chi in extract = (Ilg chljml)(volume of extract, ml)
.
Ilg chI in extract
11 mol of chI III extract = - - - - - - --- - - -
molecular weight of chi
where the formula weights are chlorophyll a = 893.5, chlorophyll h = 907.5, and
chlorophyll c = 610.
11 mol of chi in ex tract
11 mol of chI/cell = . - ... - - - - -- --- - - -
number cells in sample
Plant Carotenoids (Strickland and Parsons, 1972)
3 (10.0(E4800Hv)
Car (IlSPU)/1 or mSPU 1m ) = -
-- - -,
(V)(Z)
where
SPU = specified plant pigment units approximating the mg
£4800 = A480 - [(3)(A750)]
Use the factor of 10.0 when the algae consist primarily of Chrysophyta, Pyrrophyta,
or both. When the algae consist predominantly of members of Chlorophyta and/or
Cyanophyta, then use the following equation:
where
3 (4.0)( E4800)( v)
Car(IlSPU/I or mSPU/m ) = - -- - - _. - .
(V)(Z)
E4800 = A480o - [(3)(A750o)]
.
3
(26.7)[1.7(E605) - E665,J(V)
Phaeoplgments (llg/1 or mg/m I =
_. - - -
- .• . . - - -
( V)(Z)