Gschwend%20thesis.pdf

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This seems unlikely to occur fast enough to build up sufficient
pentadecane against the atmospheric sink. Possibly, unexamined
species of phytoplankton contain much more pentadecane than those
studied by Clark and Blumer (1967), and these algae may be the
source of this volatile compound.
Another potential mechanism for pentadecane production is
decarboxylation of hexadecanoic acid by zooplankton, analogous to
the pathway proposed for the formation of pristane (Blumer et al.,
1964). Phytoplankton are rich in this fatty acid (Ackman et al.,
1968; Chuecas and Riley, 1969; Fisher and Schwarzenbach, 1978) and
may contain about LO mg/gm dry weight. Thus a potential standing
stock of this starting material would be between 2 and 20 ~g/kg
seawater. Should only a fraction of a percent of this fatty acid
be metabolized in a fashion similar to that proposed for phytol to
phytanic acid to pristane (Avigan and Blumer, 1968), tens of nanograms
of pentadecane/kg could result. Tetradecane and hexadecane would
not be found in similar abundance because phytoplankton do not contain
much of the appropriate fatty acid precursors. In support of this
proposed source, biogenic pentadecane and pristane appeared together
in seawater collected in the fall during a seasonal study on Georges
Bank (Energy Resources Company, Inc., 1978).
Station 6 off Peru was found to have a dinoflagellate bloom while
the more inshore stations were dominated by diatoms. Dinoflagellates
may contain greater amounts of hexadecanoic acid than
diatoms (2-3x) (Ackman et al., 1968). Thus, the correspondence of
relatively high pentadecane concentrations with the occurrence of
dinoflagellates may be the result of higher precursor availability.