Gschwend%20thesis.pdf

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Three deep samples (ca. 2000m) contained high concentrations of
pentadecane. In situ production or vertical transport and release at
depth do not seem likely to be the source of this hydrocarbon occurrence.
Advective transport of North Atlantic Deep water may have carried this
fairly stable organic compound from the biologically productive surface
formation sites to the deep ocean.
C2-benzenes were found in the recently upwelled surface water off
Peru. Concentrations of meta + para xylene
were about 4 ng/kg at 5 and
20m, about 3 ng/kg at lOOm, and about 2 ng/kg or less in the deeper
samples. This distribution indicates a surface or atmospheric source.
The air concentration necessary for the atmosphere to have been a source
was l-2 ng/l-air.
Vertical transport of m + p xylenes was indicated by the anomalously
low concentrations of these aromatic hydrocarbons in 5- and 20-m sample~
at stations 4 and 5 off Peru and by an unusually high concentration of
these compounds in seawater collected near the bottom at station 4.
Low nutrient concentrations in these surface seawaters revealed that
intense phytoplankton production had occurred, and if the m + p xylenes
became associated with biogenic particulate matter, subsequent sedimentation
and remineralization near the bottom may have introduced these compounds
to deep wa ter .
An unidentified alkene (ro 108) was recovered at up to 30 ng/kg from
surface seawater samples from the upwelling region off Peru. The GC
retention index and mass spectra of this compound showed that it is
probably structurally related to fucoserraten, an unsaturated hydrocarbon
used by the benthic alga, Fucus, as a sexual chemotactic signal. The
unknown compound may be formed by isomerization of fucoserraten (trans,