Gschwend%20thesis.pdf

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A family of straight chain aldehydes from hexanal to decanal
were observed in seawater from off Peru at i to 10 ng/kg. As was
the case for the other volatiles, concentrations were highest in
offshore surface samples (figure 2-9).
DISCUSSION
Total Volatiles
For all three regions, 40 ng/kg was the maximum concentration
observed for an individual compound. Total levels in surface samples
were on the order of LO-30 ng/kg in the Sargasso Sea and about LOO
ng/kg near Peru. Deep samples contained 10 ng/kg or less. Three
general explanations for this scarcity of volatiles may be offered.
First, there may be a lack of sources. In areas such as the Sargasso
Sea and the western Equatorial Atlantic, primary production of
organic matter is low and consequently might not be expected to be
an important source for the volatiles. Also, remoteness from land
for these Atlantic regions may have precluded transport from natural
or industrial terrestrial sources. The coastal region of Peru is a
sparsely populated coastal desert near the area where the samples
were acquired. Thus, terrestrial sources to these nearshore samples
are unlikely to be strong, in spite of offshore winds. However,
primary production in this upwelling region was very high at the
time of sampling, and although elevated total volatile concentrations
were seen, it seems likely that some other mechanism limits these
organic constituents dissolved in seawater to only tracé levels.
The levels of the volatile organic compounds may also be limited
by a dynamic remineralization system. Investigators using several