Gschwend%20thesis.pdf

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Pentadecane and the halomethanes were found especially in brown
algae. Two green algae produced 2 different 17-carbon mono~unsaturated
hydrocarbons.
Zostera marina, a higher vascular plant, also released bromoform
to seawater. This observation suggests that Zostera, and other algae,
may concentrate it from seawater.
Volatile Organic Compounds Not Detected in Seawater.
Volatile ketones, esters, and ethers were not deteèted in seawater.
The methodology used was capable of the analysis of suitable representa-
tives of these compound classes. Esters are known to have biological
sources, but they were also found to be rapidly degraded chemically in
seawater (half life of a few days with respect to hydrolysis in seawater).
Ketones and ethers are at least as stable chemically as aldehydes, therefore
their observed absence may be attributed to insufficient sources.
Several other volatile compound groups were not detected, and there-
fore upper limits for their occurrence in Vineyard Sound seawater of less
than lng/kg have been established. Lower n-alkanes (nC8-nCI2)' prominent
constituents of petroleum products; chlorinated benzenes, produced by
ch10rina tion of sewage and drinking water; and halogenated terpenes, known
from red algae of shallow Pacific coast regions, were not detected.
Terpenes were also undetectable. This res~lt is consistent with the
following scenario for delivery of C2- and C3-benzenes and terpenes from
land to the sea. The terrestrial sources of both generate atmoslheric
concentrations of individual compounds of 1-40 nfl-air near the site of
input. The tertiary and allylic hydrogens of the terpenes and the benzylic